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Displaying 901 - 925 of 1896

Transitory Temperatures of Organic-Film Coated Specimens under Outdoor Exposure

March 2, 2012
Author(s)
William C. Thomas, Christopher C. White, Walter E. Byrd
A mathematical model is presented and validated for predicting the temperature of thin polymeric films bonded to substrate materials. The National Institute of Standards and Technology provided specimen temperature and simultaneous weather data for tests

Freeform Fabricated Scaffolds with Roughened Struts that Enhance both Stem Cell Proliferation and Differentiation by Controlling Cell Shape

March 1, 2012
Author(s)
Girish Kumar, Carl G. Simon Jr., Michael S. Waters, Tanya M. Farooque, Marian F. Young
We demonstrate that imparting freeform fabricated (FFF) scaffolds with surface roughness on their struts enhances osteogenic differentiation of primary human bone marrow stromal cells (hBMSCs) by controlling cell shape. Previous work showed that hBMSCs

Rippling Instability of Supported Polymer Nanolines

February 21, 2012
Author(s)
Vijaya R. Tirumala, Christopher M. Stafford, Leonidas E. Ocola, Jack F. Douglas, L. Mahadevan
The swelling response of polymer line gratings supported on a rigid substrate has direct implications on their mechanical stability during pattern transfer in nanofabrication. The polymer lines, when swollen in a good solvent, undergo a rippling

Direct observation of nucleation and early stages of growth of GaN nanowires

February 15, 2012
Author(s)
Rosa E. Diaz, Renu Sharma, Karalee Jarvis, Qinglei Zhang, Subhash Mahajan
We report for the first time direct observations of the nucleation and early stages of growth of GaN nanowires. The nanowires were formed by exposing Au + Ga droplets to ammonia. The formation process was observed in situ, and controlled in real time using

Nanoscale structure measurements for polymer-fullerene photovoltaics

February 3, 2012
Author(s)
Dean M. DeLongchamp, Regis J. Kline, Andrew A. Herzing
This review covers methods to measure key aspects of nanoscale structure in organic photovoltaic devices based on polymer-fullerene bulk heterojunctions. The importance of nanoscale structure to the power conversion efficiency and stability of these

Antibacterial amorphous calcium phosphate nanocomposite with quaternary ammonium salt and silver nanoparticles

February 2, 2012
Author(s)
Nancy Lin, Lei Cheng, Michael D. Weir, Hockin H. Xu, Joseph M. Antonucci, Alison M. Kraigsley, Sheng Lin-Gibson, Xuedong Zhou
Objectives. Calcium and phosphate ion-releasing resin composites are promising for remineralization; however, so far there has been no report on imparting a potent antibacterial capability to these composites. The objectives of this study were to

Control of Molecular Mass Distributions in Enzymatic Lactone Polymerizations

February 2, 2012
Author(s)
Santanu S. Kundu, Peter M. Johnson, Kathryn L. Beers
Using a model developed for the enzyme catalyzed polymerization and degradation of poly(caprolactone), we illustrate methods and the kinetic mechanisms necessary to improve molecular mass distributions by manipulating equilibrium reactions in the kinetic

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 D. 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
Displaying 901 - 925 of 1896
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