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  • Electronic Resource  (3)
  • 1995-1999  (3)
  • ROSETTA  (2)
  • PEFC
  • 1
    ISSN: 1572-8838
    Keywords: anode ; nanocrystalline ; PEFC ; PEM fuel cell ; Pt–Ru alloy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract High energy ball milling, an industrially amenable technique, has been used to produce CO tolerant unsupported Pt–Ru based catalysts for the oxidation of hydrogen in polymer electrolyte fuel cells. Nanocrystalline Pt0.5–Ru0.5 alloys are easily obtained by ball-milling but their performances as anode catalysts are poor because nanocrystals composing the material aggregate during milling into larger particles. The result is a low specific area material. Improved specific areas were obtained by milling together Pt, Ru and a metal leacheable after the milling step. The best results were obtained by milling Pt, Ru, and Al in a 1:1:8 atomic ratio. After leaching Al, this catalyst (Pt0.5–Ru0.5 (Al4)) displays a specific area of 38 m2g−1. Pt0.5–Ru0.5 (Al4) is a composite catalyst. It consists of two components: (i) small crystallites (∼4 nm) of a Pt–Al solid solution (1–3 Al wt%) of low Ru content, and (ii) larger Ru crystallites. It shows hydrogen oxidation performance and CO tolerance equivalent to those of Pt0.5–Ru0.5 Black from Johnson Matthey, the commercial catalyst which was found to be the most CO tolerant one in this study.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Space science reviews 90 (1999), S. 313-319 
    ISSN: 1572-9672
    Keywords: ROSETTA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The International Rosetta Mission, approved by the Science Programme Committee of the European Space Agency as the Planetary Cornerstone Mission in ESA's long-term programme Horizon 2000, will rendezvous in 2011 with Comet 46P/Wirtanen close to its aphelion and will study the nucleus and the evolution of the coma for almost two years until it reaches perihelion. In addition to the investigations performed by the scientific instruments on board the orbiter, a Surface Science Package (Rosetta Lander) will be deployed onto the surface of the nucleus early during the near-nucleus study phase. On its way to Comet 46P/Wirtanen, Rosetta will fly by and study the two asteroids 4979 Otawara and 140 Siwa.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Space science reviews 90 (1999), S. 321-328 
    ISSN: 1572-9672
    Keywords: ROSETTA ; Space Mission Target Comets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Comet 46P/Wirtanen is the target comet of the ROSETTA mission. Here, we give an overview of the information currently available on this comet from remote-sensing observations. Main emphasis is put on the description of the coma in terms of morphology, composition and evolution. We also summarize the current knowledge of the basic properties of the nucleus, in particular its size and rotational properties.
    Type of Medium: Electronic Resource
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