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Displaying 1326 - 1350 of 1721

Near-Field Optical Imaging of Microphase Separated and Semi-Crystalline Polymer Systems

January 1, 2002
Author(s)
Michael J. Fasolka, Lori S. Goldner, A Urbas, Jeeseong C. Hwang, Kathryn Beers, P DeRege, Evan L. Thomas
Polymer self-assembly presents an attractive means of creating the micro- and nano-patterned spatial arrays required for many opto-electronic and coatings technologies. Two of these ordering processes are microphase separation (MS), exhibited by block

Non-Cavitational Tensile Creep in Lu-Doped Silicon Nitride

January 1, 2002
Author(s)
F Lofaj, Sheldon M. Wiederhorn, Gabrielle G. Long, B Hockey, P R. Jemian, L Browder, April Andreas
The tensile creep behavior of a Lu-based silicon nitride, SN 281, was studied in the temperature range 1400 C to 1550 C with test periods of up to 10 000 h. Strain rates were 3 to 5 orders of magnitude less than those for Yb-based grades of silicon nitride

Phase Relationships and Phase Formation in the System BaF 2 -BaO-Y 2 O 3 -CuO x -H 2 O

January 1, 2002
Author(s)
Winnie K. Wong-Ng, Lawrence P. Cook, J Suh, Igor Levin, Mark D. Vaudin, Ron Feenstra, James P. Cline
The interplay of melting equilibria and reaction kinetics is important during formation of the Ba2YCu3O6+x (Y-213) phase from starting materials in the quaternary reciprocal system Ba,Y,Cu//O,F. For experimental investigation of the process we are using a

Research and Challenges in Applied Mechanics

January 1, 2002
Author(s)
K P. Chong, Martin Chiang
The United States Government pursues diligent funding of basic research because it confers a preferential economic advantage1. The National Science Foundation (NSF) and the National Institute of Standards and Technology (NIST) have supported basic research

The Fracture Toughness Round Robins in VAMAS: What We Have Learned

January 1, 2002
Author(s)
George D. Quinn
Over the last thirteen years the Versailles Advanced Materials and Standards (VAMAS) project has conducted five full fledged, international round robins on ceramic fracture toughness characterization. As many as forty laboratories have done thousands of

Thermal Shock Resistance of Silicon Nitrides Using an Indentation-Quench Test

January 1, 2002
Author(s)
S K. Lee, J D. Moretti, Brian R. Lawn
The thermal shock resistance of silicon nitrides is investigated using an indentation-quench procedure. Four grades of commercially available silicon nitrides with different microstructures are investigated. The extension of Vickers radial cracks is

Unexpected Ground State Structures in Relaxor Ferroelectrics

January 1, 2002
Author(s)
Benjamin P. Burton, Eric J. Cockayne
Cluster expansion Hamiltonians derived from pseudopotential total energies were used to predict ground-state (GS) cation configurations for some A(B^{3+}1⁄2B'^{5+}1⁄2)O3, A(B^{2+}{1/3}B'^{5+}{2/3})O3 , and [A^{1+}1⁄2A'^{3+}1⁄2]BO3 perovskites. Predicted GS

Variation of Electrical Properties With Exfoliation Condition in Nanocomposites

January 1, 2002
Author(s)
M M. McBrearty, Anthony J. Bur, S C. Roth
Dielectric measurements were made on clay filled nylon and polyethylene-ethyl vinyl acetate (PE-EVA) copolymer nanocomposites during processing by extrusion. Nylon without clay had a small dielectric dispersion while PE-EVA did not. The addition of natural

Convalent Cationization Method for the Analysis of Polyethylene by Mass Spectrometry

December 1, 2001
Author(s)
Barry J. Bauer, William E. Wallace, B M. Fanconi, Kathleen M. Flynn
Polyethylene and other polyolefins have not been amenable to mass spectrometric characterization of molecular mass distribution due to the ineffectiveness of conventional methods of cationization. The lack of polar groups, unsaturation, and aromaticity

Crystal Chemistry and Phase Equilibria of Selected SrO- R 2 O 3 -CuO x and Related Systems, R=Lanthanides and Yttrium

December 1, 2001
Author(s)
Winnie K. Wong-Ng, Qingzhen Huang, Igor Levin, James A. Kaduk, J Dillingham, T J. Haugan, J Suh, Lawrence P. Cook
This paper investigates and reviews the trend of phase formation and crystal chemistry of selected series of compounds in SrO- R 2O 3-CuO x and related systems. Including in this discussion are (Ba,Sr) 2RCu 3O 6+x, where M = selected representative and

Dispersion and Nucleating Effects of Clay Fillers in Nanocomposite Polymer Films

December 1, 2001
Author(s)
V Ferreiro, G Schmidt, Charles C. Han, Alamgir Karim
Nanocomposite polymeric materials offer unique properties such as mechanical, electrical, thermal, etc. Such property enhancements are induced not only by the physical presence of the filler but also by the interaction of the polymer with the filler and

Rapid Calculation of X-Ray Absorption Near Edge Structure Using Parallel Computation

December 1, 2001
Author(s)
Charles E. Bouldin, June E. Sims, Howard Hung, J J. Rehr, A L. Ankudinov
Modeling x-ray absorption near edge structure (XANES) requires computationally intensive calculations. We show that parallel processing reduces the time required for XANES calculations by a factor of up to 50 over desktop computers. Parallel processing is
Displaying 1326 - 1350 of 1721