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Displaying 951 - 975 of 1935

Polymer Dynamics in Constrained Geometries

February 1, 2012
Author(s)
Christopher Soles, Ryan Nieuwendaal, Huagen H. Peng
The wide-spread interest in the dynamical property of organic materials under strong states of confinement largely began with differential scanning calorimeter (DSC) measurements in the early 90's of the glass transition and heat capacity of glass forming

Elucidating the Influence of Local Structure Perturbations on the Metal-Insulator Transitions of V1-x MoxO2 Nanowires: Mechanistic Insights from an X-ray Absorption Spectroscopy Study

January 27, 2012
Author(s)
Bruce Ravel, C Patridge, Luisa Whittaker-Brooks, S Banerjee
The substitutional doping of Mo within VO2 substantially alters the electronic and structural phase diagrams of the host lattice, most notably by bringing the technologically relevant metal-insulator phase transition temperature in closer proximity to room

DNA Molecules Descending a Nanofluidic Staircase by Entropophoresis

January 26, 2012
Author(s)
Samuel M. Stavis, Jon C. Geist, Michael Gaitan, Laurie E. Locascio, Elizabeth A. Strychalski
A complex entropy gradient for confined DNA molecules was engineered for the first time. Following the second law of thermodynamics, this enabled the directed self-transport and self-concentration of DNA molecules. This new nanofluidic method is termed

The Effects of Folding on High Strength Fibers Used in Soft Body Armor

January 23, 2012
Author(s)
Haruki Kobayashi, Walter G. McDonough, Joy Dunkers, Jae H. Kim, Hae-Jeong Lee, Scott Wight, Amanda L. Forster, Kirk D. Rice, Gale A. Holmes
Poly (p-phenylene benzobisoxazole) (PBO) fibers have been used in soft body armor (SBA) because of their high mechanical strength. However, there was an unexpected failure of a first responder's SBA which was composed of PBO fiber that was in service for

Direct Observation of Hydrogen Spillover in Ni-Loaded Pr-Doped Ceria

January 17, 2012
Author(s)
Vaneet Sharma, Peter A. Crozier, Renu Sharma, James B. Adams
Hydrogen-spillover in Ni-loaded Pr-doped ceria (PDC) was directly observed using an environmental transmission electron microscope (ETEM). Localized reduction of ceria in a H2 atmosphere was observed and attributed to gas-Ni-ceria interactions at the three

Does Shape Matter? Bioeffects of Gold Nanomaterials in a Human Skin Cell Model

January 13, 2012
Author(s)
Nicole M. Schaeublin, Laura K. Braydich-Stolle, Elizabeth I. Maurer, Kyoungweon Park, Robert I. MacCuspie, A R M N. Afrooz, Navid B. Saleh, R.A. Vaia, Saber Hussain
Gold nanomaterials (AuNMs) have distinctive electronic and optical properties, making them ideal candidates for biological, medical, and defense applications. Therefore, it is imperative to evaluate the potential biological impact of AuNMs before employing

Effect of elastic deformation on frictional properties of few-layer graphene

January 9, 2012
Author(s)
Alexander Y. Smolyanitsky, Jason P. Killgore, Vinod K. Tewary
We describe the results of Brownian dynamics (BD) simulations of an AFM tip scanned on locally suspended few-layer graphene. The effects of surface compliance and sample relaxation are directly related to the observed friction force. We demonstrate that

Spherical indentation testing of poroelastic relaxations in thin hydrogel layers

December 16, 2011
Author(s)
Edwin Chan, Yuhang Hu, Peter M. Johnson, Zhigang Suo, Christopher Stafford
In this work, we present the Poroelastic Relaxation Indentation (PRI) testing approach for quantifying the mechanical and transport properties of thin layers of poly(ethylene glycol) hydrogel materials with thicknesses on the order of 200 m. Specifically

Experimentally Based Methodology for Charge Pumping Bulk Defect Trapping Correction

December 15, 2011
Author(s)
Jason T. Ryan, Richard G. Southwick, Jason P. Campbell, Kin P. Cheung, Chadwin Young, John S. Suehle
We develop a simple experimental approach to remove bulk trap contributions from charge pumping data collected on devices which suffer from large amounts of bulk dielectric electron trapping. The approach is more desirable and easier to implement than

Characterization of Stabilized Zero Valent Iron Nanoparticles

December 10, 2011
Author(s)
Lauren F. Greenlee, Stephanie A. Hooker
The demonstrated toxicity of certain groups of organic micropollutants in water sources has motivated research in developing novel materials that are able to remove dissolved organic molecules from an aqueous system through adsorption and/or degradation

Automated Data Processing and Quantification in Polymer Mass Spectrometry

December 1, 2011
Author(s)
Till Gruendling, Christopher Barner-Kowollik, William E. Wallace, Charles M. Guttman, Anthony J. Kearsley
An overview is given of some new techniques in quantitative composition and molecular mass distribution measurement of synthetic polymers by mass spectrometry. New concepts in data analysis, including peak picking and integration, are also described.

Mechanical Properties of Polymer Nano-Films

November 28, 2011
Author(s)
Junghyun Lee, Jun Y. Chung, Christopher Stafford
Three fundamental mechanical properties of supported glassy polystyrene films with thickness ranging from 250 nm to 9 nm were quantitatively determined by a recently developed wrinkling-cracking method. Films below about 40 nm showed a decrease in both

In situ monitoring of enzyme-catalyzed (co)polymerizations by Raman spectroscopy

November 10, 2011
Author(s)
Matthew T. Hunley, Atul Bhangale, Santanu S. Kundu, Peter M. Johnson, Michael S. Waters, Richard Gross, Kathryn Beers
In situ, fiber optic-based Raman spectroscopy provided real time monitoring of enzyme-catalyzed ring-opening homo- and copolymerizations of ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL). A custom designed reactor equipped with in situ fiber optic probe

Reliability Testing of Advanced Interconnect Materials

November 10, 2011
Author(s)
Robert R. Keller, Mark C. Strus, Ann C. Chiaramonti Debay, David T. Read, Younglae Kim, Yung J. Jung
We describe the development of electrical test methods to evaluate damage that determines reliability in advanced, small-scale conductors, including damascene copper and aligned carbon nanotube networks. Rapid thermal cycling induced during high-current AC

Structure and Properties of Polymer Electrolyte Membranes Containing Phosphonic Acids for Anhydrous Fuel Cells

November 9, 2011
Author(s)
Kirt A. Page, Christopher L. Soles, Huagen H. Peng, Do Y. Yoon, Sung-Il Lee, Myeongsoo Song, Kyung-Hwan Yoon, Wolfgang Meyer
Recently, water-free, proton conducting, polymer electrolytes are attracting attention due to their possible application as fuel cell membranes at intermediate temperatures (100 ºC to 200 ºC). Phosphonic acid groups are considered feasible anhydrous proton

Viscoelastic Property Mapping with Contact Resonance Force Microscopy

November 4, 2011
Author(s)
Jason P. Killgore, Donna C. Hurley, Dalia Yablon, Joseph Turner, Philip Yuya, Roger Proksch, Anil Gannepalli, Andy Tsou
We demonstrate accurate nanoscale mapping of loss and storage modulus on a polystyrene-polypropylene blend with contact resonance force microscopy (CR-FM). The viscoelastic properties are extracted from spatially resolved maps of the contact resonance

Influence of chain stiffness on thermal and mechanical properties of polymer thin films

October 25, 2011
Author(s)
Jessica M. Torres, Chengqing C. Wang, E. B. Coughlin, John P. Bishop, Richard A. Register, Robert A. Riggleman, Christopher Stafford, Bryan D. Vogt
The effect of main chain stiffness and side chain flexibility on the elastic modulus and glass transition temperature (Tg) of thin polymer films is investigated using non-traditional polymers formed from 5-(2-phenylethylnorbornene). Depending on the

Determination of Moisture Content of Single-Wall Carbon Nanotubes

October 17, 2011
Author(s)
Rolf L. Zeisler, Rabia Oflaz, Ralph E. Sturgeon, Rick L. Paul, Brian E. Lang, Jeffrey A. Fagan, Joseph W. Lam, Anthony Windust, P Grinberg, Benoit Simard, Christopher T. Kingston
Several techniques were evaluated for the establishment of reliable water/moisture content of single-wall carbon nanotubes. Karl Fischer titration (KF) provides for a direct measure of the water content and was used for benchmarking against results
Displaying 951 - 975 of 1935
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