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Displaying 776 - 800 of 1721

Chemical Twinning of the Pyrochlore Structure in the System Bi 2 O 3-Nb 2O 5

January 28, 2007
Author(s)
Ian E. Grey, W G. Mumme, Terrell A. Vanderah, Robert S. Roth, C Bougerol-Chaillout
New ternary bismuth iron niobates having structures based on chemical twinning of pyrochlore are described. Bi5.67Nb10FeO35 has hexagonal symmetry, P63/mmc, a = 7.432(1) , c = 31.881(2) , Z = 2 and Bi9.3Nb16.9Fe1.1O57.8 has rhombohedral symmetry, R-3m, a =

Contact Mechanics of Layered Elastic Materials: Experiment and Theory

January 26, 2007
Author(s)
P M. McGuiggan, Jay S. Wallace, Douglas T. Smith, I Sridhar, Z Zheng, K L. Johnson
This paper reports an experimental and theoretical investigation of the indentation of a layered elastic solid, with special reference to the surface force apparatus (SFA). The contacting surfaces of the SFA comprise a 3-layer material: a thin mica surface

A High-Throughput Thermoelectric Power-Factor Screening Tool for Rapid Construction of Thermoelectric Property Diagrams

January 23, 2007
Author(s)
Makoto Otani, Nathan Lowhorn, Peter K. Schenck, Winnie K. Wong-Ng, Martin L. Green, K Itaka, H Koinuma
We have developed a high throughput screening tool that maps out thermoelectric power factors of combinatorial composition-spread film libraries. The screening tool allows us to measure the electrical conductivity and Seebeck coefficient of over 1000

Influence of Oxygen Vacancies on the Dielectric Properties of Hafnia

January 22, 2007
Author(s)
Eric J. Cockayne
First-principles calculations were used to study the effects of neutral and 2+ charged oxygen vacancies on the dielectric properties of crystalline HfO2. In agreement with previous results, the neutral vacancy is more stable on the 4-fold coordinated site

Analysis of C-S-H Gel and Cement Paste by Small-Angle Neutron Scattering

January 16, 2007
Author(s)
Andrew J. Allen, J Thomas
The role of small-angle x-ray and neutron scattering (SAXS and SANS) in the characterization of cement is briefly reviewed. The unique information obtainable from SANS analysis of C-S-H gel in hydrating cement is compared with that obtainable by other

Composition and Density of Amorphous Calcium-Silicate-Hydrate in Cement

January 16, 2007
Author(s)
Andrew J. Allen, J Thomas, Hamlin M. Jennings
Despite intensive research for over a century, the main binding reaction product of cement hydration, calcium-silicate-hydrate (C-S-H) gel, is not fully understood. By combining absolute-calibrated small-angle and ultrasmall-angle neutron and x-ray

Biaxial Stress Dependence of AlxGa 1-x As Photoluminescence

January 13, 2007
Author(s)
Grady S. White, Albert J. Paul, Kristine A. Bertness, Lawrence H. Robins
A study was conducted of the room temperature photoluminescence behavior of AlxGa1-xAs as a function of tensile, equi-biaxial stress for x = 0, 0.198, 0.36, 0.498, and 0.809. The composition range included both the direct and the indirect band gap regions

On the Vickers Indentation Fracture Toughness Test

January 4, 2007
Author(s)
George D. Quinn, Richard Bradt
The Vickers indentation fracture toughness test or VIF is addressed by considering its origins and the numerous equations that have been applied along with the technique to estimate the fracture resistance, or the KIc of ceramics. Initiation and

Buckling Modes of Elastic Thin Films on Elastic Substrates

January 1, 2007
Author(s)
Haixia Mei, Jun Y. Chung, Honghui Yo, Christopher Stafford, Rui Huang
Subject to compression, a thin elastic film bonded to an elastic substrate can buckle. Two buckling modes have been observed. On a stiff substrate, the film buckles when it is partly delaminated from the substrate, resulting in localized buckle patterns

Cell Morphology and Migration Linked to Substrate Rigidity

January 1, 2007
Author(s)
Yong Ni, Martin Chiang
A mathematical model, based on thermodynamics, was developed to demonstrate the substrate mechanics influences the cell morphology and migration. The mechanisms by which substrate rigidity are translated into cell morphological changes and cell movement

Effect of Surface Properties on Wrinkling of Ultrathin Films

January 1, 2007
Author(s)
Rui Huang, Christopher Stafford, B D. Vogt
Thin films bonded to compliant substrates often develop wrinkles when subjected to an applied or inherent compressive stress. This paper presents a bilayer model to account for surface effects on the wrinkling of ultrathin solid films. Assuming a surface

Length Dependent Uptake of DNA-Wrapped Single Walled Carbon Nanotubes

January 1, 2007
Author(s)
Matthew Becker, Jeffrey Fagan, Nathan D. Gallant, Barry J. Bauer, Vardhan Bajpai, Erik K. Hobbie, Silvia H. De Paoli Lacerda, Kalman D. Migler, J P. Jakupciak
DNA-wrapped single wall carbon nanotubes (SWNTs) with broad length distributions are shown to reduce the viability of IMR90 primary human lung fibroblast cells above the (23 to 25) ug/mL concentration regime. Furthermore using well-defined length fractions
Displaying 776 - 800 of 1721