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Displaying 2026 - 2050 of 2347

Chemorheological Investigation on the Environmental Susceptibility of Sealants

August 18, 2009
Author(s)
Kar T. Tan, David J. Benatti, Christopher C. White, Donald L. Hunston, Deborah S. Jacobs
One of the major problems with any sealant system is its susceptibility to hostile environments, such as heat, moisture, ultraviolet radiation, oxygen, mechanical stress and biochemical attack. Prolonged exposure to these environments leads to substantial

Diffusion Under Temperature Gradient: A Phase-field Model Study

August 11, 2009
Author(s)
Rashmi R. Mohanty, Jonathan E. Guyer, Yong Ho Sohn
A diffuse interface model was devised and employed to investigate the effect of thermotransport (a.k.a., thermomigration) process in single-phase and multi-phase alloys of a binary system. Simulation results show that an applied temperature gradient can

REFERENCE MATERIALS FOR RHEOMETERS AND THE FLOW TABLE

August 3, 2009
Author(s)
Chiara F. Ferraris, Zughuo Li, Mona Mohseni, Nicholas Franson
Oil is the most used standard material for the calibration of rheometers. Other products are used to calibrate flow devices, i.e., the flow table is calibrated using a mixture of oil and silica powder. The oil is a Newtonian liquid while the oil-silica

Moisture Attack on Adhesive Joints: Roles of Adhesive and Interface Properties

July 22, 2009
Author(s)
Donald L. Hunston, Kar T. Tan, Sushil K. Satija, Christopher C. White, Bryan D. Vogt, Cyril Clerici
It is well-known that moisture will attack many adhesive joints. A particularly interesting feature is the observation that when the moisture level in certain systems exceeds a critical concentration, the bonded joint shows a dramatic loss of strength. A

Degradation and Nanofiller Release of Polymer Nanocomposites Exposed to UV

July 15, 2009
Author(s)
Tinh Nguyen, Bastien T. Pellegrin, Alexander J. Shapiro, Xiaohong Gu, Joannie W. Chin
Nanofillers are increasingly used to enhance multifunctional properties of polymers. However, recent research suggests that nanomaterials may have a negative impact on the environmental health and safety. Since polymers are susceptible to photodegradation

Long-Term Performance of Nano-Filled Polymeric Materials: Effect of ZnO Nanoparticles on Photodegradation of a Waterborne Polyurethane Coating

July 8, 2009
Author(s)
Xiaohong Gu, Dongmei Zhe, Minhua Zhao, Guodong Chen, Nhieu Ly, Paul E. Stutzman, Li Piin Sung, Tinh Nguyen, Joannie W. Chin
Polymers are widely used as exterior coatings in buildings, bridges, aircrafts and automobiles for both protection and aesthetic purposes. However, the service life of the applied coatings is limited due to the photodegradation of polymers induced by

Comprehensive Evaluation of AIMS Texture, Angularity, and Dimension Measurements

July 3, 2009
Author(s)
Enad M. Mahmoud, Leslie L. Gates, Eyad A. Masad, Sinan T. Erdogan, Edward Garboczi
Aggregates are the most widely used construction materials in the world in structures built from both asphaltic and portland cement concrete composites. The performance of these composites is affected by aggregate shape characteristics (e.g., angularity

Microscale Polymer-Nanotube Composites

July 2, 2009
Author(s)
Erik K. Hobbie, Jeffrey A. Fagan, Jan Obrzut, Steven D. Hudson
Microscopic polymer colloids with an interfacial coating of purified single-wall carbon nanotubes (SWCNTs) have been synthesized from length and type sorted SWCNTs. Aqueous SWNCT suspensions sorted through density-gradient ultracentrifugation are used to

Inter-Laboratory Comparisons of NbTi Critical Current Measurements

June 22, 2009
Author(s)
Arno Godeke, D. Turrioni, T. Boutboul, Najib Cheggour, A. K. Ghosh, Loren F. Goodrich, M Meinesz, A. den Ouden
We report on a multi-institute comparison of critical current data, measured on a modern Large Hadron Collider (LHC) NbTi wire that has shown a standard deviation below 1% in critical current density spread in more than 1500 measurements. Inter-laboratory

Internal tin Nb3Sn conductors engineered for fusion and particle accelerator applications

June 22, 2009
Author(s)
Jeffrey Parrell, Y. Zhang, Michael Field, M Meinesz, Yonghua Huang, H Miao, Seungok Hong, Najib Cheggour, Loren F. Goodrich
The critical current density (Jc) of Nb3Sn strand has been significantly improved over the last several years. For most magnet applications, high Jc internal tin has displaced bronze process strand. The highest Jc values are obtained from distributed

Test Results of the First US ITER TF Conductor in SULTAN

June 22, 2009
Author(s)
Nicolai N. Martovetsky, Daniel R. Hatfield, John R. Miller, Chen-yu Gung, Joel S. Schultz, Najib Cheggour, Loren F. Goodrich, Pierluigi Bruzzone, Boris Stepanov, Rainer Wesche, Bernd Seeber
The US Domestic Agency is one of six parties supplying TF cable-in-conduit conductors (CICCs) for ITER. Previous tests have shown that measured performance of the TF CICCs can be much lower than expected from the strand properties at the projected uniaxial

Determination of the Electron Escape Depth for NEXAFS Spectroscopy

June 2, 2009
Author(s)
Daniel A. Fischer, K E. Sohn, M D. Dimitriou, Jan Genzer, C Hawker, E. J. Kramer
Depth profiling using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy was used to determine the carbon atom density as a function of depth by analyzing the post-edge signal in NEXAFS spectra. We show that the common assumption in the

High Strain Rate Tissue Simulant Measurements Using digital Image Correlation

June 1, 2009
Author(s)
Steven P. Mates, Richard L. Rhorer, Richard Everett, Kirth Simmonds, Amit Bagchi
Measuring the response of soft materials to high strain rate deformation is extremely challenging because of the difficulty of achieving dynamic equilibrium during high strain rate mechanical testing such as Kolsky bar testing. Digital image correlation

Carbon Nanomaterials Standards Efforts at NIST

May 24, 2009
Author(s)
Jeffrey A. Fagan
Development of carbon nano-materials for applications has been hindered to date by a lack of standard protocols, i.e. documentary standards, and physical standards such as reference materials, which enable the common inter-comparison between laboratories

Capillary Instability in Nanoimprinted Polymer Films

May 21, 2009
Author(s)
Kyle J. Alvine, Yifu Ding, Hyun Wook Ro, Brian C. Okerberg, Alamgir Karim, Christopher L. Soles, Jack F. Douglas
Capillary forces play an active role in defining the equilibrium structure of nanoscale structures. This effect can be especially pronounced in soft materials such as polymers near or above their glass transition temperatures where material flow is

The Origin of Critical Relative Humidity in Adhesion

May 11, 2009
Author(s)
Christopher C. White, Kar T. Tan, Bryan D. Vogt, Donald L. Hunston
Water is ubiquitous in the atmosphere. Unfortunately, adhesive bonding is susceptible to the environmental attack of water leading to significant depreciation in joint strength and subsequently to premature failures [1-6]. This susceptibility of bonding to

Demonstration of Impedance Matching Using a mu-Negative (MNG) Metamaterial

April 14, 2009
Author(s)
Christopher L. Holloway, R. B. Greegor, C. G. Parazzoli, J. A. Nielsen, M. H. Tanielian, D Vier, S Schultz, Richard Ziolkowski
A mu-negative (MNG) metamaterial hemisphere was used to demonstrate impedance matching for a magnetic loop. The metamaterial was comprised of copper spirals deposited on an alumina substrate. The spirals, hemisphere, and magnetic loop were designed to
Displaying 2026 - 2050 of 2347
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