Experimental study of flame stabilization in low Reynolds and Dean number flows in curved mesoscale ducts

Flame stabilization during non-premixed combustion in curved ducts with a diameter of the order of magnitude of the premixed flame thickness of the reactants was investigated experimentally, since it has been established that this is a configuration with potential advantages in the context of “micro”-combustion. It was shown that, in such “mesoscale” tubes, a stable flame oscillation including extinction/re-ignition phenomena can be established for steady boundary conditions. These oscillations lead, under appropriate conditions, to sound emission in the 50–350 Hz range. This was a mode of stabilization in addition to the “classical” steady flamelet, stabilized through thermal losses to the duct walls at higher values of the Reynolds number. Curvature of the duct was shown to have minimal effect on reactant mixing, which was diffusion-controlled, but significantly affected flame thickness and stabilization. To probe the fuel-oxidizer mixing in the U-shaped, optically accessible tubes, laser induced fluorescence of acetone fuel dopant was used, and the flame structure was studied using OH PLIF. The various stabilization regimes are discussed in terms of the Reynolds and Dean numbers of the tube flow.     

Hydroxylamine-functionalised silica surfaces for biochip applications

The syntheses of triethoxy and trimethoxy silanes possessing an unprotected hydroxylamine group are described. The grafting of these coupling agents at the surface of oxidised silicon wafers was studied. Accessibility of the hydroxylamine group at the surface was demonstrated with chemical reagents, and the surface proved efficient for covalent immobilisation of peptides possessing the COCHO function.     

Thermal decompositions of some transition metal salicylates

The thermal decompositions of divalent cobalt, cadmium, nickel and copper salicylates and intermediates formed during the decomposition processes were investigated by means of thermogravimetry. Two intermediates were identified in each case, except for copper(II) salicylate.

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Zusammenfassung Die thermische Zersetzung von divalentem Kobalt-, Cadmium-, Nickel- und Kupfersalicylat und von während der Zersetzungsprozesse gebildeten Zwischenprodukten wurde thermogravimetrisch untersucht. Mit Ausnahme von Kupfer(II)-salicylat konnten in jedem Falle zwei intermediäre Produkte identifiziert werden.

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The authors wish to thank Perkin-Elmer for its collaboration