Oxygen dependence

Nickel oxide, NiO, which is the only oxide formed by nickel during oxidation in air, has a very naiTow range of iroir-stoichiomen y, the maximum oxygeir/nickel ratio probably being 1.001. The oxygen dependence of the deviation from non-stoichiometry is and hence dre oxidation rate... 

Corrosion (in acid solutions) At low potentials iron will be oxidised to Fe and Fe203 reduced to Fe, and the a-p will be > 10" g ion/1 water will be reduced to hydrogen or remain stable, depending upon whether E is below or above curve/. At high potentials iron will be oxidised to Fe and Fe203 will dissolve to form Fe (Ef i /f 2 = 0-76 V) water will be stable or will be oxidised to oxygen, depending upon whether E is below or above curve m, respectively. 

Figure 2.2 shows the cell density and DO level in a pilot-scale aeration vessel. The role of dissolved oxygen in the treatment system is absolutely vital. Therefore the DO level must be maintained at not less than 3-4 ppm in the wastewater for effective aeration. SCP production is veiy oxygen-dependent. The results would be very satisfactory if pure oxygen is used. 

Taking into account the close relationship to pyridines one would expect 2-pyridones to express similar type of reactivities, but in fact they are quite different. 2-Pyridones are much less basic than pyridines (pKa 0.8 and 5.2, respectively) and have more in common with electron-rich aromatics. They undergo halogenations (a. Scheme 10) [67] and other electrophilic reactions like Vilsmeier formylation (b. Scheme 10) [68,69] and Mannich reactions quite easily [70,71], with the 3 and 5 positions being favored. N-unsubstituted 2-pyridones are acidic and can be deprotonated (pJCa 11) and alkylated at nitrogen as well as oxygen, depending on the electrophile and the reaction conditions [24-26], and they have also been shown to react in Mitsonobu reactions (c. Scheme 10) [27]. 

M-substituted 2-pyridones can be prepared by N-alkylation, under basic conditions (pfCa of the amide proton is 11). The resulting anion can then react on either nitrogen or oxygen depending on the conditions employed [24-27]. Also, several direct methods for the construction of N-substituted 2-pyridones have been reported. Two such examples can be seen in Scheme 3 where the first example (a) is an intramolecular Dieckmann-type condensation [28] and the second (b) is a metal-mediated [2 -I- 2 + 2] reaction between alkynes with isocyanates [29,30]. 

Johnson MS, IB Zhulin, M-E R Gapuzan, BL Taylor (1997) Oxygen-dependent growth of the obligate anaerobe Desulfovibrio vulgaris Hildenborough. J Bacterial 179 5598-5601. 

Davies I, GF White, WJ Payne (1990) Oxygen-dependent desulphation of monomethyl sulphate by Agrobacterium sp. M3C. Biodegradation 1 229-241. 

The results shown in Figure 4 indicate that the oxygen dependency of the acetic acid formation is higher than that of the citraconic anhydride formation. Therefore, use of a low oxygen concentration is beneficial to the selectivity to citraconic anhydride, though it is disadvantageous to the reaction rate. 

Baker, S.S. and Baker, R.D. (1990). CaCo cell damage by oxygen dependent processes. Gastroenterology 98 A157. 

The design of propellants for solid fuel rockets differs considerably from that for ordnance, because of the lower operating pressures, usually below 15 MPa. To understand the principles involved it is first necessary to give a brief account of rocket propulsion. In this account considerations will be restricted to motors based on solid propellants. Motors based on liquid fuels, such as petroleum fractions and liquid oxygen, depend on combustion processes of non-explosive type. 

The NADH- and oxygen-dependent microsomal metabolism of the di-, tri- and tetraethyl substituted derivatives of germanium, tin and lead was shown to give rise to ethylene as a major product and ethane as a minor product27. These reactions were shown to be catalyzed by the liver microsomal fractions. 

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