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Displaying 626 - 650 of 925

Lengthscale Effects on Exchange Coupling in Co-Pt Ll 0 +Ll 2 Nanochessboards

September 1, 2016
Author(s)
Eric P. Vetter, Liwei Geng, Priya Ghatwai, Dustin A. Gilbert, Yongmei Jin, William A. Soffa, Jerrold A. Floro
The Co-Pt nanochessboard is a quasi-periodic, nanocomposite tiling of Ll 0 and Ll 2 magnetic phases that offers a novel structure for the investigation of exchange coupling, relevant to permanent magnet applications. Periodicity of the tiling is controlled

The Low-Temperature Structural Behavior of Sodium 1-Carba-closo-decaborate: NaCB 9 H 10

August 21, 2016
Author(s)
Hui Wu, Wan Si NMN Tang, Wei Zhou, Jacob Daniel Tarver, Vitalie Stavila, Craig Brown, Terrence J. Udovic
Two ordered phases of the novel solid superionic conductor sodium 1-carba-closo-decaborate (NaCB 9H 10) were identified via synchrotron x-ray powder diffraction in combination with first-principles calculations and neutron vibrational spectroscopy. A

Structure and Dynamics of Interacting Nanoparticles in Semidilute Polymer Solutions

August 17, 2016
Author(s)
Ryan Poling-Skutvik, Katrina Irene S. Mongcopa, Antonio Faraone, Suresh Narayanan, Jacinta C. Conrad, Ramanan Krishnamoorti
We investigate the structure and dynamics of silica nanoparticles and polymer chains in semidilute solutions of high molecular weight polystyrene in 2-butanone to determine the effect of long range interparticle interactions on the coupling between

Structure of Polyelectrolyte Brushes in the Presence of Multivalent Counterions

August 9, 2016
Author(s)
Jing Yu, Jun Mao, Guangcui Yuan, Sushil K. Satija, Zhang Jiang, Wei Chen, Matthew Tirrell
Polyelectrolyte brushes are of great importance to a wide range of fields, ranging from colloidal stabilization to responsive and tunable materials to lubrication. We synthesized high-density polystyrene sulfonate (PSS) brushes using surface force

A 3He beam stop for minimizing gamma-ray and fast-neutron background

August 6, 2016
Author(s)
Danyal J. Turkoglu, Robert G. Downing, Wangchun Chen, Dagistan Sahin, Jeremy C. Cook
Prompt gamma-ray activation analysis facilities with high neutron currents (≥109 s-1) generate triton-induced fast neutrons from 6Li-loaded collimators and beam stops at rates that soon damage gamma-ray detectors. We develop an alternative beam stop design

Current status and future directions for in situ transmission electron microscopy

August 6, 2016
Author(s)
M. L. Taheri, Eric Stach, Ilke Arslan, Peter A. Crozier, Kabius Bernd, Thomas LaGrange, Andrew Minor, Seiji Takeda, Mihaela M. Tanase, Jakob B. Wagner, Renu Sharma
This review article discusses the current and future possibilities for the application of in situ transmission electron microscopy to reveal synthesis pathways and functional mechanisms in complex and nanoscale materials. The findings of a group of

Crystal Structures and Phase Equilibria in the Hafnium-Palladium System

August 1, 2016
Author(s)
Judith K. Stalick, Richard M. Waterstrat
Portions of the Hf-Pd phase diagram have been reinvestigated in an attempt to resolve contradictions that occur between two previous studies. Techniques employed include Rietveld refinement using x-ray and high-temperature neutron diffraction data to

Precision measurement of the radiative beta decay of the free neutron

June 14, 2016
Author(s)
Jeffrey S. Nico, Kevin J. Coakley, Maynard S. Dewey, Thomas R. Gentile, Hans P. Mumm, Alan Keith Thompson, M J. Bales, R. Alarcon, C. D. Bass, E J. Beise, H Breuer, Jim Byrne, R L. Cooper, B. O'Neill, F E. Wietfeldt, T E. Chupp
The theory of quantum electrodynamics predicts that a continuous spectrum of photons is emitted in the beta decay of the free neutron in addition to a proton, an electron, and an antineutrino. We report the first precision test of the shape of the photon

MPInterfaces: A Materials Project based Python Tool for a High Throughput Computational Screening of Interfacial Systems

May 31, 2016
Author(s)
Arunima Singh, Kiran Mathew, Joshua Grabriel, Kamal Choudhary, Susan B. Sinnott, Albert Davydov, Francesca M. Tavazza, Richard G. Hennig
A Materials Project based open-source python tool, MPInterfaces, has been developed to automate the high throughput computational screening and study of interfacial systems. The framework encompasses creation and manipulation of interface structures for

Applications of Neutron Imaging and Future Possibilities

May 15, 2016
Author(s)
Daniel S. Hussey, David L. Jacobson
Neutron imaging applications exploit the power of neutrons to penetrate through metals and measure small concentrations of hydrogen and lithium with high sensitivity. The recent advances made in digital imaging devices have enabled many novel neutron

Dynamic Onset of Feynman Relation in the Phonon Regime

May 9, 2016
Author(s)
Lu Deng, Edward W. Hagley, Yan Li, Chengjie Zhu
The Feynman relation 1, a much celebrated condensed matter physics gemstone for more than 70 years, predicts that the density excitation spectrum and structure factor of a condensed Bosonic system in the phonon regime drops linear and continuously to zero

Neutron Limit on the Strongly-Coupled Chameleon Field

March 11, 2016
Author(s)
Michael G. Huber, Muhammad D. Arif, David G. Cory, R. Haun, B. Heacock, Joachim Nsofini, Dimitry A. Pushin, P Saggu, C.B Shahi, William M. Snow, A.R. Young
The physical origin of the dark energy which causes the accelerated expansion rate of the universe is one of the major open questions of cosmology. One set of theories postulates the existence of a self-interacting scalar eld for dark energy coupling to

The JAR Extractor: a Soxhlet Modified Into a Large-Diameter Wafer Washer

October 20, 2015
Author(s)
Richard J. Sheridan, Aaron V. Kirchhoff
A closed-atmosphere, solvent-recirculating, large diameter wafer washer was fabricated for neutron reflectivity research at the National Institute of Standards and Technology. Manufacturing feasibility for the public sector was increased by simplicity in

Equilibrium Self-Assembly, Structure, and Dynamics of Clusters of Star-Like Micelles

October 17, 2015
Author(s)
Vivek M. Prabhu, Shrinivas Venkataraman, Yi Yan Yang, James Hedrick
Small-angle neutron scattering and static and dynamic light scattering have characterized the hierar-chical structure and dynamics of clusters of self-assembled star-like micelles formed by oligocarbonate-fluorene func-tionalized polyethylene glycol

Hydration of Conduction Pores in KcsA Potassium Channel and M2 Proton Channel

September 14, 2015
Author(s)
J L. Blasic, David L. Worcester, Klaus Gawrisch, Philip A. Gurnev, Mihaela Mihailescu
Water-filled hydrophobic cavities of channel proteins serve as gateways for transfer of ions across membrane. However, functional implications of hydration-dehydration transitions remain elusive due to difficulties to detect and quantify water in channel

Macroscopic Subkelvin Refrigerator Employing Superconducting Tunnel Junctions

August 10, 2015
Author(s)
Xiaohang NMN Zhang, Peter J. Lowell, Brandon L. Wilson, Galen C. O'Neil, Joel N. Ullom
In this paper, we demonstrate a general-purpose macroscopic refrigerator based on the transport of hot electrons through superconducting tunnel junctions. Our refrigerator is intended to provide access to temperatures below those accessible using pumped

Development of an Ultra-Pure, Carrier-Free 209Po Solution Standard

July 23, 2015
Author(s)
Ronald Colle, Ryan P. Fitzgerald, Lizbeth Laureano-Perez
Ultra-pure, carrier-free 209Po solution standards have been prepared and standardized for their massic alpha-particle emission rate. The standards, which will be disseminated by the National Institute of Standards and Technology (NIST) as Standard

A New Cold Neutron Imaging Instrument at NIST

July 6, 2015
Author(s)
Daniel S. Hussey, Christoph W. Brocker, David L. Jacobson, Thomas R. Gentile, Wangchun Chen, Elias M. Baltic, DV Baxter, J. Doskow, Muhammad D. Arif
The NIST neutron imaging program will build a new imaging instrument in the NCNR guide hall at the end of the neutron guide NG-6, beginning operation in summer of 2014. The NG-6 guide has a spectrum that is strongly peaked at a neutron wavelength of 5 Å
Displaying 626 - 650 of 925
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