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Displaying 1251 - 1275 of 1721

Grain Growth in Relaxor Ferroelectrics

August 1, 2002
Author(s)
J Blendell, Jay S. Wallace
The mechanisms controlling normal and exaggerated grain growth in lead magnesium niobate - lead titanate (PMN - PT) ceramics have been investigated by varying the PbO-based liquid phase volume fraction, the PT content and the MgO stoichiometry. There is a

MALDI MS Characterization of Covalent Cationized Polyethylene

August 1, 2002
Author(s)
Sheng Lin-Gibson, D L. Brunner, David L. VanderHart, Barry J. Bauer, B M. Fanconi, Kathleen M. Flynn, William E. Wallace
Polyolefins, saturated hydrocarbon polymers such as polyethylene (PE) and polypropylene, are, by production volume, the most widely used of all A new method for the mass spectrometry of saturated polyolefins whereby an organic cation is covalently bonded

MeasuringThe Modulus of Polymer Films by Strain-Induced Buckling Instabilities

August 1, 2002
Author(s)
Christopher M. Stafford, C Harrison, Alamgir Karim, Eric J. Amis
We present a high-throughput technique for measuring the Young s modulus of thin polymer films. This technique exploits a strain-induced buckling instability observed in films supported on elastomeric substrates. By employing a combinatorial polymer film

Optimizing the Covalent Cationization Method for the Mass Spectrometry of Polyolefins

August 1, 2002
Author(s)
Sheng Lin-Gibson, L Brunner, David L. VanderHart, Barry J. Bauer, B M. Fanconi, Charles M. Guttman, William E. Wallace
Previously a new method was introduced for the mass spectrometry of polyolefins whereby an organic cation is covalently bonded to the polymer to produce the necessary ionization for the creation of intact gas?phase macromolecules by matrix-assisted laser

Site-Specific Valence-Band Photoemission Study of A-Fe 2 O 3

August 1, 2002
Author(s)
C Y. Kim, Michael Bedzyk, E J. Nelson, Joseph Woicik, L E. Berman
We have measured the site-specific valence-electronic structure of α-Fe 2O 3 by using a spatially modulated X-ray standing wave as the excitation source for photoemission. Contributions to the valence band density of states from oxygen and iron ions are

The Nature and Origin of Tribochemistry

August 1, 2002
Author(s)
Stephen M. Hsu, J Zhang, Z Yin
The origin of tribochemistry is from the rubbing of surfaces together. The precise nature of the chemical reactions and the driving force behind the reactions are not known except for a few simple chemical systems. In boundary lubrication, it is difficult

Fabricating Planar Nanoparticle Assemblies With Number Density Gradients

July 1, 2002
Author(s)
R R. Bhat, Daniel A. Fischer, Jan Genzer
We report on preparing assemblies of gold nanoparticles with continuous gradients in number density on flat silica-covered substrates. The methodology consists of: i) first forming a one dimensional molecular gradient of amino groups (-NH2) on the

Investigation of Morphology and Interface in Polymer Composite Thin Films

July 1, 2002
Author(s)
C. K. Chiang, Li Piin Sung, R Popielarz
Laser scanning confocal microscopy (LSCM) has been applied to examine the filler particles and their distribution in BaTiO3-polymer composite films. We have measured thin-slice images of the composite films at various depths from the film surface and

Quantitation of Polymer End Groups Using MALDI TOF MS

July 1, 2002
Author(s)
A P. Weaver, Charles M. Guttman, Kathleen M. Flynn
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) has been employed to analyze polystryrene mixtures of molecular mass ca. 4000u. The component polymers of thes mixtures are identical except for their end groups

Some Issues in Particle Size and Size Distribution Characterization of Powders

July 1, 2002
Author(s)
Ajitkumar Jillavenkatesa, James F. Kelly, S J. Dapkunas
Size and size distribution measurement of powders are conducted using different techniques of size analysis.Underlying all these techniques are certain fundamental issues that influence the accuracy and reproducibility ofthe results. A thorough

Ceramic Based Layer Structures for Biomechanical Applications

June 1, 2002
Author(s)
Brian R. Lawn
A survey of recent advances in the analysis of ceramic-based layer structures for biomechanical applications is presented. Data on model layer systems, facilitating development of explicit fracture mechanics relations for predicting critical loads to

Compact Force Sensors for Low-Force Mechanical Probe Calibration

June 1, 2002
Author(s)
Douglas T. Smith, S Woody, Jon R. Pratt
The loading mechanisms of instrumented indentation machines are often calibrated using deadweights. In many cases, due to the geometry of the loading frame, the applied deadweight is tensile, while the indentation leads to be measured are compressive. In

Cracking in Brittle Laminates from Concentrated Loads

June 1, 2002
Author(s)
H Chai, Brian R. Lawn
A study is made of the crack resistance of multilaminates consisting of brittle layers interleaved with compliant interlayers and bonded to compliant substrates. Specific attention is paid to flexure generated radial cracks in the undersurfaces of

Crystal Structure of the Compound Bi 2 Zn 2/3 Nb 4/3 O 7

June 1, 2002
Author(s)
Igor Levin, T G. Amos, J Nino, Terrell A. Vanderah, I Reaney, C A. Randall, M T. Lanagan
The crystal structure of Bi2Zn2/3Nb4/3O7 was determined using a combination of electron, X-ray and neutron powder diffraction. The compound crystallizes with a monoclinic zirconolite-like structure (C2/c (No.15) space group, a=13.1037(9) , b=7.6735(3) , c
Displaying 1251 - 1275 of 1721