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Displaying 826 - 850 of 902

In-Situ Investigation of Water Transport in an Operating PEM Fuel Cell Using Neutron Radiography: Part 2 - Transient Water Accumulation in an Interdigitated Cathode Flow Field

July 27, 2007
Author(s)
Jon P. Owejan, T Trabold, David L. Jacobson, D Baker, Daniel S. Hussey, Muhammad D. Arif
An interdigitated cathode flow field was tested in-situ with neutron radiography to measure the water transport through the porous gas diffusion layer in a PEM fuel cell. Constant current density to open circuit cycles were tested and the resulting liquid

Neutron Images of the Through-Plane Water Distribution of an Operating PEM Fuel Cell

July 27, 2007
Author(s)
Daniel S. Hussey, David L. Jacobson, Muhammad Arif, Jon P. Owejan, Jeffrey J. Gagliardo, T Trabold
Neutron imaging has proven an invaluable tool for water metrology in operating proton exchange membrane fuel cells. Due to limitations in scintillator-based detector resolution, neutron imaging has been applied only to assessing the in-plane water

Voltage Instability in a Simulated Fuel Cell Stack Correlated to Cathode Water Accumulation

July 22, 2007
Author(s)
Jon P. Owejan, T Trabold, Jeffrey J. Gagliardo, Robert N. Carter, Daniel S. Hussey, David L. Jacobson, Muhammad D. Arif
Single fuel cells running independently are often used for fundamental studies of water transport. It is also necessary to assess the dynamic behavior of fuel cell stacks comprised of multiple cells arranged in series, thus providing many paths for flow of

Effects of Ozonolysis and Subsequent Growth of Quantum Dots on the Electrical Properties of Freestanding Single-walled Carbon Nanotube Films

June 2, 2007
Author(s)
L C. Teague, S Banerjee, S S. Wong, Curt A. Richter, Bindhu Varughese, J Batteas
A significant challenge exists in probing the transport behavior of chemically modified single- walled carbon nanotubes (SWNTs). Thin films of SWNTs offer one facile approach to integration of these materials into electronics and sensing applications. Data

Neutron Collimation With Microchannel Plates: Calibration of Existing Technology and Near

April 1, 2007
Author(s)
A S. Tremsin, Daniel S. Hussey, David L. Jacobson, Muhammad D. Arif, Robert Gregory Downing, W B. Feller, David F. Mildner
A new type of high performance and compact neutron collimator can be manufactured from Gd- or B-doped microchannel plates (MCPs). Structures only a few mm thick have very narrow rocking curves and high out-of-angle rejection ratios, as observed previously

PEM Fuel Cell Membrane Hydration Measurement by Neutron Imaging

November 8, 2006
Author(s)
D J. Ludlow, M K. Jensen, C M. Calebrese, G A. Eisman, S Yu, C Dannehy, Daniel S. Hussey
Neutron scattering experiments on a proton exchange membrane fuel cell wereperformed to assess the ability to quantify water in the membrane and electrode/gas diffusion layers. Previous studies have shown that liquid water is easily resolved within flow

Comparative Measures of Single Wall Carbon Nanotube Dispersion

September 14, 2006
Author(s)
Jeffrey A. Fagan, Brian Landi, Idan Mandelbaum, Vardhan Bajpai, Barry J. Bauer, Kalman D. Migler, Jeffrey R. Simpson, Angela R. Hight Walker, Ryan Raffaelle, Erik K. Hobbie
Model polymer composites of DNA wrapped single-wall carbon nanotubes (SWNTs) dispersed in polyacrylic acid are used for a systematic comparison of the different metrologies currently used to evaluate SWNT dispersion. Application of a pH-controlled

Crystal Structure of the Class IV Adenylyl Cyclase From Yersinia Pestis

March 1, 2006
Author(s)
N Smith, Sung Kim, Prasad T. Reddy, David T. Gallagher
ABSTRACT: The crystal structure of the class IV adenylyl cyclase from Yersinia pestis is reported at 1.9 resolution. The class IV fold is distinct from the previously described folds for class II and class III ACs. The dimeric Yp AC-IV folds into an

Structure of Alanine Dehydrogenase from Archaeoglobus: Active Site Analysis and Relation to Bacterial Cyclodeaminases and Mammalian mu Crystallin

September 3, 2004
Author(s)
David T. Gallagher, H G. Monbouquette, I Schroder, Hugh Robinson, Marcia J. Holden, N Smith
The hyperthermophilic archaeon Archaeoglobus fulgidus contains an L-Ala dehydrogenase (AlaDH, EC 1.4.1.1) that is not homologous to known bacterial dehydrogenases and appears to represent a previously unrecognized archaeal group of NAD-dependent

Quantifying Uncertainty in Nuclear Analytical Measurements

July 1, 2004
Author(s)
Lloyd A. Currie
This document resulted from a request at an International Atomic Energy Agency Consultants' Meeting. Information is based on a document Foundationsand future of detection and quantification limits prepared for the 1996 Proceedings of the Joint Statistical

Crystal Structure of the Complex Between Thrombin and the Central "E" Region of Fibrin

March 2, 2004
Author(s)
I Pechik, J Madrazo, M W. Mosesson, I Hernandez, G L. Gilliland, L Medved
Non-substrate interactions of thrombin with fibrin play an important role in modulating its procoagulant activity. To establish the structural basis for these interactions, we crystallized PPACK-inhibited thrombin in complex with a fragment, Eht

Crystallization and Phasing of Alanine Dehydrogenase From Archaeoglobus Fulgidus

December 1, 2003
Author(s)
N Smith, M P. Mayhew, Hugh Robinson, A Heroux, D Charlton, Marcia J. Holden, David T. Gallagher
Alanine dehydrogenase (AlaDH) from the hyperthermophilic archaeon A. fudgidus is a dimer of 35 kdal chains. The gene (AF1665) is annotated as an ornithine cyclodeaminase based on homology with the ornithine deaminase/ mu crystallin enzyme family. It

Interdiffision in Polystyrene and End-Functional Polystyrene Thin Films Near a Solid Surface

September 10, 2003
Author(s)
Chengqing C. Wang, Vivek M. Prabhu, Christopher L. Soles, B D. Vogt, Wen-Li Wu, Eric K. Lin, Sushil K. Satija
Polymer interdiffusion near the polymer/solid interface is studied using neutron reflectometry. Bilayers of hydrogenated polystyrene (hPS) and deuterated polystyrene (dPS) or hydrogenated dicarboxy terminated polystyrene (hPS(COOH)2) and dPS are prepared

X-Ray Topography of Microgravity-Grown Ribonuclease S Crystals

August 1, 2003
Author(s)
David T. Gallagher, C Stover, D Charlton, L Arnowitz, David R. Black
Crystals of the enzyme RNase S were grown at micro and unit gravity using a dialysis-based dynamically controlled device. Crystals were grown at 24 C on space shuttle flights STS 93 and STS 95. Control crystals were grown simultaneously in ground
Displaying 826 - 850 of 902
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