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Search Publications

NIST Authors in Bold

Displaying 37951 - 37975 of 73697

Properties of water and aqueous systems: Metrological applications

November 19, 2004
Author(s)
Daniel G. Friend, Allan H. Harvey
Water and aqueous systems are widely used in metrology, which is a major focus of the National Institute of Standards and Technology (NIST). Standards such as those produced by IAPWS can be used to calibrate instruments and validate protocols. In this work

Standards of time and frequency at the outset of the 21st century

November 19, 2004
Author(s)
Scott Diddams, James C. Bergquist, Steven R. Jefferts, Christopher W. Oates
In this paper we review state-of-the-art atomic time and frequency standards and discuss some of their uses in science and technology. After fifty years of development, microwave atomic clocks based on cesium have achieved fractional uncertainties below 1

Unusual Multilayered Structures in PEO/Laponite Nanocomposite Films

November 19, 2004
Author(s)
Avinash Dundigalla, Sheng Lin-Gibson, F Ferreiro, M M. Malwitz
The unusual structure of poly-ethylene-oxide and Laponite clay in transparentnanocomposite films was investigated using scanning electron, atomic force, optical microscopy, and X-ray scattering. Each method is sensitive to different aspects of structural

Competing Damage Modes in All-Ceramic Crowns: Fatigue and Lifetime

November 15, 2004
Author(s)
Yu Zhang, Brian R. Lawn
A study is made of fracture from cyclic loading of WC spheres on the surfaces of brittle layers on compliant substrates, as representative of repetitive occlusal contact on dental crowns. Several damage modes radial cracks at both top surface and

Time-division multiplexing of high-resolution TES X-ray microcalotimeters: Four pixels and beyond

November 15, 2004
Author(s)
W.Bertrand (Randy) Doriese, James A. Beall, Steven Deiker, William Duncan, S. L. Ferreira, Gene C. Hilton, Kent D. Irwin, Carl D. Reintsema, Joel Ullom, Leila R. Vale, Yizi Xu
We present experimental results from a four-pixel array of transition-edge-sensor, x-ray microcalorimeters read out through a single amplifier channel via a time-division superconducting quantum interference device multiplexer. We map the dependence of the

Boltzmann Test of Slonczewski's Theory of Spin Transfer Torque

November 12, 2004
Author(s)
J Xiao, A Zangwill, Mark D. Stiles
We use a matrix Boltzmann equation formalism to test the accuracy of Slonczewski's theory of spin-transfer torque in thin-film heterostructures where a non-magnetic spacer layer separates two non-collinear ferromagnetic layers connected to non-magnetic

Effect of Steel and Tungsten Carbide Ball Indenters on Rockwell Hardness Tests

November 11, 2004
Author(s)
Li Ma, Samuel R. Low III, J L. Fink
Rockwell hardness (HR) is a valuable and widely used indentation hardness test for evaluating mechanical properites of metallic materials. For the Rockwell scales that use a ball indenter, either a steel or tungsten carbide (WC) ball indenter is permitted

Monolayer Formation of PBLG-PEO Block Copolymers at the Air-Water Interface

November 11, 2004
Author(s)
Y Park, Y W. Choi, SK Park, C S. Cho, Michael J. Fasolka, Daeson Sohn
Physicochemical properties of PBLG (poly(gamma-benzyl-L-glutamate))-PEO (poly(ethylene oxide)) diblock copolymers composed of PBLG as the hydrophobic rod component and PEO as the hydrophilic component were investigated at the air-water interface. Surface

Permeability of Polymeric Scaffolds With Defined Pore Micro-Architecture and Interconnectivity Fabricated by Solid Free-Form Microprinting

November 7, 2004
Author(s)
K W. Lee, E Jabbari, L L. Lu, B L. Currier, Joy Dunkers, Martin Chiang, John A. Tesk, Marcus T. Cicerone, M J. Yaszemski
The hydraulic permeability of was measured as a function of interconnectivity of the pores. The hydraulic permeability of porous scaffolds for tissue engineering of bone was measured as interconnectivity of the pores was changed from 100 % to 70 %. The

The optical calcium frequency standards of PTB and NIST

November 5, 2004
Author(s)
U Sterr, C Degenhardt, H Stoehr, Ch. Lisdat, H Schnatz, J Helmcke, F Riehle, G Wilpers, Christopher W. Oates, Leo W. Hollberg
We describe the current status of the optical calcium frequency standard with laser-cooled neutral atoms realized in two different laboratories for the purpose of developing a possible future optical atomic clock. Frequency measurements performed at PTB

A New 'Wrinkle' in Nanometrology

November 1, 2004
Author(s)
Christopher M. Stafford
Nanotechnology promises to revolutionize a growing set of materials applications ranging from electronics to drug delivery to ballistic protection. However, the quest to engineer mate-rials on the nanoscale (e.g., in the form of ultrathin films) is met

A Water Setting Tetracalcium Phosphate- Dicalcium Phosphate Dihydrate Cement

November 1, 2004
Author(s)
Elena F. Burguera, F Guitian, Laurence C. Chow
This paper reports the development of a calcium phosphate cement, comprising tetracalcium phosphate (TTCP) and dicalcium phosphate dihydrate (DCPD), that hardens in 14 min with water as the liquid or 6 min with a 0.25 mol/L sodium phosphate as the liquid

Ad-hoc Network Systems and Applications

November 1, 2004
Author(s)
Hamid Gharavi
We have implemented a quantum key distribution (QKD) system with polarization encoding at 850 nm over 1 km of optical fiber. The high-speed management of the bit-stream, generation of random numbers and processing of the sifting algorithm are all handled
Displaying 37951 - 37975 of 73697
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