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Displaying 451 - 475 of 1729

Viscoelastic and poroelastic relaxations of polymer-loaded hydrogels

July 5, 2012
Author(s)
Blessing Deeyaa, Christopher Stafford, Edwin Chan, Peter M. Johnson
In this work, we study the viscoelastic and poroelastic contributions on the relaxation behavior of a polymer-loaded hydrogel using a recently develop Poroelastic Relaxation Indentation (PRI) measurement technique. By applying a generalized relaxation

Pigment and Nanofiller Photoreactivity Database

July 2, 2012
Author(s)
Stephanie S. Watson, I-Hsiang Tseng, Tarek Marray, Bastien T. Pellegrin
The service life and durability of nanocomposites that contain fillers are affected by photocatalytic properties of these fillers, particularly narrow band gap metal oxides (NBMOs) such as titanium dioxide (TiO2). When illuminated with ultraviolet (UV)

Solid-Phase Synthesis of Ammonium Ionenes

June 24, 2012
Author(s)
Matthew T. Hunley, Kathryn L. Beers
Ionenes are polyelectrolytes with the charge along the polymer backbone. These polymers possess a precisely-defined charge density, making them ideal as physical crosslinkers for high performance elastomers as well as gene transfection agents. However

Tensile behavior of single PPTA fibers measured by the Kolsky bar using the direct fiber clamping method

June 11, 2012
Author(s)
Jae Hyun Kim, Nathanael A. Heckert, Stefan D. Leigh, Haruki Kobayashi, Walter G. McDonough, Richard L. Rhorer, Kirk D. Rice, Gale A. Holmes
The Kolsky bar test has been widely used in measuring material behavior under high strain rate conditions. In particular, this methodology has been used to characterize the high strain rate behavior of polymer and polymer composites during ballistic impact

Optimization of Imaging Polymer Based Scaffolds Using X-Ray Microcomputed Tomography

May 15, 2012
Author(s)
David E. Morris, Melissa L. Mather, Carl Simon Jr., John A. Crowe
The performance of polymer based scaffolds used in regenerative medicine is linked to their structural properties and as such strategies for structural characterization of scaffolds have been developed. X-ray microscopic computed tomography (X-ray micro CT

Gas-Foamed Scaffold Gradients for Combinatorial Screening in 3D

May 1, 2012
Author(s)
Carl G. Simon Jr., Kaushik Chatterjee, Alison M. Kraigsley, Joachim Kohn, Durgadas Bolikal
Current methods for screening cell-material interactions typically utilize two-dimensional (2D) culture format where cells are cultured on flat surfaces. However, there is a need for combinatorial and high-throughput screening methods to systematically

Dielectrophoretic Cell Capture on Polyester Membranes

April 2, 2012
Author(s)
Conni Hanke, Petra S. Dittrich, Darwin Reyes-Hernandez
A new system for dielectrophoretic cell capture on porous polyester (PET) membranes is presented. Conventional photolithographic techniques were used to fabricate gold microelectrodes on a PET membrane. We characterized these electrodes to proof that there

In Situ Raman Monitoring of Ring-Opening Copolymerizations

March 25, 2012
Author(s)
Matthew T. Hunley, Santanu S. Kundu, Peter M. Johnson, Kathryn Beers
Recent advances in enzyme, metal, and organic catalysts have enabled the development of advanced functional polymers from cyclic ester and cyclic carbonate monomers. In this work, we present an in situ technique to monitor ring-opening polymerization using

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

Ultra-small-Angle X-ray Scattering - X-ray Photon-Correlation Spectroscopy Studies of Incipient Structural Changes in Amorphous Calcium Phosphate Based Dental Composites

February 28, 2012
Author(s)
Fan Zhang, Andrew Allen, Lyle E. Levine, Laura Espinal, Joseph M. Antonucci, Drago Skrtic, Justin N. O'Donnell, Jan Ilavsky
The local structural changes in amorphous calcium phosphate (ACP) based dental composites were studied upon heating using both static, bulk measurement techniques and recently developed ultra-small angle X-ray scattering - X-ray photon correlation

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

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

Synthesis and characterization of antimicrobial dimethacrylates containing quaternary ammonium functionalities for dental and biomedical applications

October 27, 2011
Author(s)
Joseph M. Antonucci, Diana N. Zeiger, Sheng Lin-Gibson, Bruce O. Fowler, Nancy J. Lin
The widespread incidence of recurrent caries has resulted in the need for improved dental restorative materials, including effective antibacterial, polymeric dental materials. Compounds with quaternary ammonium groups are known to reduce bacterial growth

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
Displaying 451 - 475 of 1729
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