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  • Chemostat  (1)
  • Condensed Matter: Electronic Properties, etc.  (1)
  • EXAFS  (1)
  • Food chain  (1)
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  • 1
    ISSN: 1572-879X
    Keywords: Spreading ; dehydration ; molybdenum oxide ; silica ; EXAFS ; Raman spectroscopy ; preparation ; clusters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In contrast to the frequently reported lack of interaction between hexavalent molybdenum and SiO2 and the tendency of silica-supported MoO3 to coalescence, it has been found that on dehydration small molybdenum oxide clusters spread over a silica support. A combined Raman spectroscopy-X-ray absorption study shows a significantly altered structure of the molybdenum oxide phase after dehydration. In EXAFS the total Mo-Mo coordination number drops from 3.27 to 0.20 after anin situ thermal treatment at 673 K. The increase of the peak in the XANES region (Is -→ 4d) indicates that the coordination sphere of the molybdenum atoms strongly alters after dehydration. The Raman spectra reflect the change of the structure through a shift of the position of the terminal Mo=O bond from 944 to 986 cm−1 and the disappearance of the bridged Mo-O-Mo vibration at 880 cm−1. It is concluded that dehydration produces almost isolated molybdenum sites in this highly dispersed sample. Water ligands stabilize the oligomeric clusters under ambient conditions; the removal of water causes spreading of these clusters.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of mathematical biology 36 (1997), S. 24-40 
    ISSN: 1432-1416
    Keywords: Key words: Bifurcation diagram ; Chaos ; Chemostat ; Food chain ; Existence and stability ; Limit cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract.  The dynamic behaviour of food chains under chemostat conditions is studied. The microbial food chain consists of substrate (non-growing resources), bacteria (prey), ciliates (predator) and carnivore (top predator). The governing equations are formulated at the population level. Yet these equations are derived from a dynamic energy budget model formulated at the individual level. The resulting model is an autonomous system of four first-order ordinary differential equations. These food chains resemble those occuring in ecosystems. Then the prey is generally assumed to grow logistically. Therefore the model of these systems is formed by three first-order ordinary differential equations. As with these ecosystems, there is chaotic behaviour of the autonomous microbial food chain under chemostat conditions with biologically relevant parameter values. It appears that the trajectories on the attractors consists of two superimposed oscillatory behaviours, a slow one for predator–top predator and a fast one for the prey–predator on one branch at which the top predator increases slowly. In some regions of the parameter space there are multiple attractors.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2017-03-08
    Description: Author(s): A. E. M. Smink, J. C. de Boer, M. P. Stehno, A. Brinkman, W. G. van der Wiel, and H. Hilgenkamp The two-dimensional electron system at the interface between LaAlO 3 and SrTiO 3 has several unique properties that can be tuned by an externally applied gate voltage. In this work, we show that this gate tunability extends to the effective band structure of the system. We combine a magnetotransport s… [Phys. Rev. Lett. 118, 106401] Published Mon Mar 06, 2017
    Keywords: Condensed Matter: Electronic Properties, etc.
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
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