Stoichiometry precise control

There is no published work on the kinetics of simultaneous redox catalysts, with precisely controlled stoichiometry in the gas. A catalyst that would selectively reduce NO in preference to oxygen is difficult to find and is unnecessary. A mixture of catalysts that is active in oxidation and reduction may be quite adequate to the task. The interaction of different catalytic sites with several gaseous species remains to be unraveled by future investigators. 

Glutamate transporters, also referred to as excitatory amino acid transporters (EAATs), clear synaptically released glutamate from the extracellular space, thus ensuring the precise control of excitatory synaptic transmission. In addition, excessive extracellular concentrations of glutamate can be neurotoxic and the efficient removal of glutamate limits pathological conditions associated with excitotoxic cell death. The transport cycle and stoichiometry of EAATs, of which hve mammalian isoforms have been characterised, is presented in Figure 9.13. 

Similarly to flame-made titanates, the precise control of the stoichiometry and material purity has an influence on the electronic properties of perovskite-type oxides such as LSC, LSCF, and BSCF. While conductivity is comparable with the highest reported in the literature (Figure 4.5), other unique properties are documented for these flame-made compositions. LSC, LSCF, and BSCF from a FSS process feature a pronounced shift of the temperature, at which the maximum conductivity is observed. The FSS process resulted in materials with an exceptional electronic conductivity, which may better match to a SOFC operated at intermediate or low temperatures. For example, LSCF cathodes based on flame-made nanopowders have shown polarization resistances in the range of 0.7 Q. cm at 592 °C [59], which are among the lowest reported for thick film layers of this material stoichiometry. Similar conclusions were drawn with respect to LSC-based cathodes, for which very low overpotentials were documented [60]. 

Ferroelectric BaTiOj films prepared by sol-gel methods were first reported by Fukushima in 1975 [58], followed by lead titanate [60], lead zirconate titanate (PZT) [62,63] and lead, lanthanum, zirconate, titanate (PLZT) [64], Superconducting YBa2Cu307 j, and thallium-based films have been prepared using sol-gel methods by several groups [48-51]. Both ferroelectric and superconducting films share similar processing criteria with optoelectronic films described in the previous section, viz. precisely controlled stoichiometry combined with well-crystallized crack-free microstructures and absence of impurities. The possibility of orientation through physico-... 

The fuel and oxidant mixture must be controlled to provide the proper flame conditions for the element being analysed. A modem spectrometer should have a gas control system providing the precise and safe regulation which is important if reproducible results are to be obtained, particularly for those elements that show great dependence on flame stoichiometry. 

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