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Displaying 626 - 650 of 1721

Finite element analysis of a crack tip in silicate glass: No evidence for a plastic zone

May 15, 2008
Author(s)
Theo Fett, G Rizzi, D Creek, Susanne Wagner, J.P. Guinn, JM Lopez-Cepero, Sheldon M. Wiederhorn
Recently, the claim was made that cracks in silicate glasses propagate by the nucleation, growth, and coalescence of cavities at crack tips, which is the same way as in metals but at a much smaller scale. This hypothesis for crack growth is based in part

Close Proximity Self-Aligned Shadow Mask for Sputter Deposition Onto a Membrane or Cavity

May 5, 2008
Author(s)
Ravi Kummamuru, L Hu, Lawrence P. Cook, M Y. Efremov, E A. Olson, Martin L. Green, L H. Allen
In this paper we report fabrication of a shadow mask designed for sputtering into cavities or on the back surface of freestanding silicon nitride (SiNx) membranes. Sputter deposition through a shadow mask typically results in spreading of the deposited

EVALUATION OF MULTI-SAMPLE MICRO-CAPILLARY RHEOMETER

May 5, 2008
Author(s)
Doyoung Moon, Anthony J. Bur, Kalman D. Migler
We present a Multi-sample Micro-capillary Rheometer (MMR) which is capable of measurements over a broad range of temperatures, viscosities and shear rates. The instrument is simple as the flow is generated by external gas pressure and the shear rate is

Crystal Structure, Stoichiometry, and Dielectric Relaxation in Bi 3.32 Nb 7.09 O 22.7 and Structurally Related Ternary Phases

April 17, 2008
Author(s)
I E. Grey, Terrell A. Vanderah, W G. Mumme, Robert S. Roth, Jorge T. Guzman, Juan C. Nino, Igor Levin
Ceramic materials which exhibit high relative dielectric permittivities and are processible at temperatures in the 1000 C to 1200 C range are of interest for embedded elements such as capacitor, resonators, and filters. Complex titanates, niobates, and

Monitoring Alignment of Osteoblast Cells Directed by Gradient Nanopatterns

April 6, 2008
Author(s)
Jirun Sun, Yifu Ding, Nancy J. Lin, Hyun Wook Ro, Christopher L. Soles, Sheng Lin-Gibson
We investigated the behavior of pre-osteoblasts cultured on polystyrene and photopolymerized ethoxylated bisphenol-A dimethacrylate gradient patterns. Gradient patterns varying in height from several hundred to 0 nm were prepared using nanoimprinting

Physical Properties of LnAg y X 4-y (Ln =La, Ce; X = Al, Ga; y 0.72)

April 1, 2008
Author(s)
Jung Y. Cho, Monica Moldovan, David P. Young, Nathan Lowhorn, Julia Y. Chan
Single crystals of LnAg(y)X(4-y) (Ln = La, Ce; X = Al, Ga; y 0.72) were synthesized by aluminum or gallium flux and characterized by single crystal X-ray diffraction. LnAg(y)X(4-y) (Ln = La, Ce; X = Al, Ga; y 0.72) crystallize in the tetragonal space group

X-Ray Imaging Optimization of 3D Tissue Engineering Scaffolds via Combinatorial Fabrication Methods

April 1, 2008
Author(s)
Yanyin Yang, Shauna M. Dorsey, Matthew Becker, Sheng Lin-Gibson, Gary E. Schumacher, Glenn M. Flaim, J Kohn, Carl G. Simon Jr.
We have developed a combinatorial method for determining optimum tissue scaffold composition for imaging by X-ray techniques. X-ray radiography and microcomputed tomography enable non-invasive imaging of implanted materials in vivo and in vitro

Characterizing Pattern Structures Using X-Ray Reflectivity

March 28, 2008
Author(s)
Hae-Jeong Lee, Christopher L. Soles, Hyun Wook Ro, Shuhui Kang, Eric K. Lin, Alamgir Karim, Wen-Li Wu
Specular X-ray reflectivity (SXR) can be used, in the limit of the effective medium approximation (EMA), as a high-resolution shape metrology for periodic patterns on a planar substrate. The EMA means that the density of the solid pattern and the space

JKR Adhesion Testing Between Biologically Relevant Surfaces

February 17, 2008
Author(s)
Adam J. Nolte, Heqing Huang, Christopher Stafford
In this work we report recent observations obtained using an adhesion testing device that utilizes the contact mechanics theory of Johnson, Kendall, and Roberts (JKR). Our goal is to develop a system capable of measuring adhesive forces between

Veneer Versus Core Failure in Adhesively Bonded All-Ceramic Crown Layers

February 14, 2008
Author(s)
James J. Lee, Jae-Young Kwon, Sanjit Bhowmick, Isabel K. Lloyd
Joining a brittle veneer to a strong ceramic core with an adhesive offers benefits over current fabrication methods for all-ceramic crowns. However, such joining introduces the possibility of subsurface radial cracking in the veneer as well as in the core

Effects of Contact Geometry Upon Pull-Off Force Measurements With a Colloidal Probe

February 5, 2008
Author(s)
Seung Ho Yang, Huan Zhang, Michael Nosonovsky, Koo-Hyun Chung
This paper examines the effects of contact geometry on the pull-off (adhesion) force between a glass sphere (colloidal probe) and a silicon substrate in an environment with controlled relative humidity. An atomic force microscope (AFM) is used to measure
Displaying 626 - 650 of 1721