University of Wisconsin-Madison

About: University of Wisconsin-Madison is a education organization based out in Madison, Wisconsin, United States. It is known for research contribution in the topics: Population & Gene. The organization has 108707 authors who have published 237594 publications receiving 11883575 citations.

Instability of Pt ∕ C Electrocatalysts in Proton Exchange Membrane Fuel Cells A Mechanistic Investigation

Abstract: Equilibrium concentrations of dissolved platinum species from a Pt/C electrocatalyst sample in 0.5 M H2SO4 at 80°C were found to increase with applied potential from 0.9 to 1.1 V vs reversible hydrogen electrode. In addition, platinum surface area loss for a short-stack of proton exchange membrane fuel cells PEMFCs operated at open-circuit voltage 0.95 V was shown to be higher than another operated under load 0.75 V. Both findings suggest that the formation of soluble platinum species such as Pt 2+ plays an important role in platinum surface loss in PEMFC electrodes. As accelerated platinum surface area loss in the cathode from 63 to 23 m 2 /gPt in 100 h was observed upon potential cycling, a cycled membrane electrode assembly MEA cathode was examined in detail by incidence angle X-ray diffraction and transmission electron microscopy TEM to reveal processes responsible for observed platinum loss. In this study, TEM data and analyses of Pt/C catalyst and cross-sectional MEA cathode samples unambiguously confirmed that coarsening of platinum particles occurred via two different processes: i Ostwald ripening on carbon at the nanometer scale, which is responsible for platinum particle coarsening from 3t o6 nm on carbon, and ii migration of soluble platinum species in the ionomer phase at the micrometer scale, chemical reduction of these species by crossover H2 molecules, and precipitation of platinum particles in the cathode ionomer phase, which reduces the weight of platinum on carbon. It was estimated that each process contributed to 50% of the overall platinum area loss of the potential cycled electrode.

A massive phytoplankton bloom induced by an ecosystem-scale iron fertilization experiment in the equatorial Pacific Ocean

Abstract: The seeding of an expanse of surface waters in the equatorial Pacific Ocean with low concentrations of dissolved iron triggered a massive phytoplankton bloom which consumed large quantities of carbon dioxide and nitrate that these microscopic plants cannot fully utilize under natural conditions. These and other observations provide unequivocal support for the hypothesis that phytoplankton growth in this oceanic region is limited by iron bioavailability.

Comparative genomics of the lactic acid bacteria

Abstract: Lactic acid-producing bacteria are associated with various plant and animal niches and play a key role in the production of fermented foods and beverages. We report nine genome sequences representing the phylogenetic and functional diversity of these bacteria. The small genomes of lactic acid bacteria encode a broad repertoire of transporters for efficient carbon and nitrogen acquisition from the nutritionally rich environments they inhabit and reflect a limited range of biosynthetic capabilities that indicate both prototrophic and auxotrophic strains. Phylogenetic analyses, comparison of gene content across the group, and reconstruction of ancestral gene sets indicate a combination of extensive gene loss and key gene acquisitions via horizontal gene transfer during the coevolution of lactic acid bacteria with their habitats.

Official Knowledge: Democratic Education in a Conservative Age

Abstract: 1. Introduction: The Politics of Official Knowledge 2. The Politics of Common-sense: Why the Right is Winning 3. Cultural Politics and the Text 4. Regulating Official Knowledge 5. Creating the Captive Audience: Channel One and the Political Economy of the Text 6. Whose Curriculum is This Anyway? (with Susan Jungck) 7. Hey Man, I'm Good! The Art and Politics of Creating New Knowledge in Schools 8. The Politics of Pedagogy and the Building of Community Appendix Education, Power, and Personal Biography: An Interview.

Avian flu: influenza virus receptors in the human airway.

Abstract: Avian and human flu viruses seem to target different regions of a patient's respiratory tract.