Oxidative regeneration

It can function anaerobically by regenerating oxidized NAD (required in the glyceraldehyde-3-phosphate dehydrogenase reaction) by reducing pymvate to lactate. 

The most convenient and commonly employed method for promoting the generation of TEMPO-oxoammonium is instead the so-called Anelh procedure It resorts to NaClO as the regenerating oxidant in 1 1 molar ratio with the substrate, under co-catalysis by EUlr. In a two-phase CH2Cl2-water system at 0°C, the oxidation of a primary alkanol does take place, to give the aldehyde selectively and in good yields (entry 3) after a few minutes. In contrast, if the reaction is run in aqueous solution with 2 molar equivalents of... 

Typical examples for type 1 are the anodic cleavages of two carbon-sulfur bonds in 1,3-dithianes [46] or dithiolanes [47]. This reaction is especially effective if performed under the conditions of indirect electrolysis using triarylamine cation radicals as regenerable oxidative mediators [47] ... 

Peroxisomes. Subcellular organelles that contain flavin-requiring oxidases and that regenerate oxidized flavin by reaction with oxygen. 

Enzymatic Methods to Regenerate Oxidized Nicotinamide Cofactors.206... 

Non-stationary operations have found large scale industrial application. An important classical example is catalytic cracking, where oil is exposed with a short residence time to a rapidly deactivating zeolitic catalyst, which is regenerated in a second step by removal of deposited coke. A novel non-stationary process is selective butane oxidation over a regenerable oxidation catalyst (see Chapter 2). Undoubtedly we will see more examples of this type of process, in which the proper catalytic step and the regeneration of the catalytic sites occur in different compartments under different conditions. A nice application involves... 

Sabatier 42 attributes the dehydration of alcohols over the surfaces of the oxides of thoria, alumina, and tungsten to the formation on the surface of these oxides, with the elimination of water, of a thin layer of an ester comparable to ethyl hydrogen sulfate. This ester is decomposed by heat into an olefin and the regenerated oxide. Thus ... 

CoQH2-Cytochrome c Reductase (Complex III) A C0QH2 generated either by complex I or complex II donates two electrons to the CoQH2-cytochrome c reductase complex, regenerating oxidized CoQ. Concomitantly it releases two protons picked up on the cytosolic face into the Intermembrane space, generating part of the proton-motive force. Within complex III, the released electrons first are transferred to an iron-sulfur cluster within complex III and then to... 

In the oxidative half-reaction, the reduced enzyme reacts with molecular oxygen to regenerate oxidized FAD. Here we focus on the presumed biologically important reductive half-reaction, in which a carbon-nitrogen bond is oxidized. 

For the enantioselective dehydrogenation of the ( -enantiomer from a racemic mixture of 3-hydroxybutyrate three different methods were used to regenerate NADP (Table 27) (83). The first method worked with catalytic concentrations of NADP and anthraquinone-2.6-disulphonate. NADPH was reoxidized by oxidized anthraquinone-2.6-disulphonate catalysed by AMAPOR (Reaction [31a]). The reduced anthraquinone-2.6-disulphonate was electrochemically reoxidized. In experiment 2 a method described by the Whitesides group (106) was applied for NADP regeneration. Oxidized anthra-quinone-2.6-disulphonate could also be used in stoichiometric concentrations (exp. 3). In such a case its electrochemical reoxidation was not necessary. Obviously in experiment 1 the product isolation is especially simple. 

These data confirm that the perovskite stabilizes palladium and suggest that the activity in catalytic combustion can be more efficiently recovered, through a regeneration oxidizing process, for these systems than for the usual Pd/y-Al203 supported catalyst, due to the palladium moiety re-incorporated in the perovskite structure at a high oxidation state (Pd" ). 

It is probable that a combination of a lower temperatures (450 C) and higher pressures to those employed in this initial study will represent the optimum conditions for maintaining catalyst surface area. In order to prevent possible reduction of the promoter to the corresponding metal (Ni/Co), hydropyrolysis should be carried out in the presence of a small amount of hydrogen sulphide to help maintain the catalyst to remain in a reasonably fiilly sulfided form. Hydropyrolysis for the virtual complete carbon removal would need to be carried out off-line since the combination of temperature, pressure and flow rate required cannot be achieved in hydrotreating units. In terms of potential applications, carbon-supported catalysts may represent the major area since these cannot be regenerated oxidatively. 

Low Temperature Adsorber Module Regeneration Oxidizer Module Regeneration Module Purified Helium Compressor Module High Temperature Filter Module Piping and Valves... 

The regenerated oxide phase with unusual microstructure possesses better gas sensing attributes. 

Tissue browning is the major problem of bamboo regeneration. Oxidized phenolic compounds produced from the damaged explants will suppress enzyme activity, darken the culture medium, and lead to the death of the explants. Treated with antioxidants and absorbents such as cysteine and ascorbic acid, polyvinylpyrrolidone (PVP) and activated carbon, will alleviate the phenolic oxidation and favor the plant regeneration (Abdelwahd et al., 2008 Sanyal et al., 2005 Toth et al., 1994). 

Reduction of fructose (or fructose-6-phosphate) by heterofermentative lac-tobacilli yields mannitol. In the process, NADH is reoxidized. Reoxidation of the coenzyme permits the bacteria to produce acetate from acetyl-phosphate (rather than regenerate oxidized coenzyme by reduction to ethanol) and, thus, produce an additional ATP. 

Degeirshein, G.A., Hurwitz, A. and Ribacoff, S. (1963) Experience with regenerated oxidized cellulose. New York StateJ. Med., Sept, 2639—43. 

Third, regeneration efficiency (i.e., the conversion of CaS04 into CaO) as determined by the Sulphation-Regeneration-Oxidation-test in a thermobalance [5] dqrends strongly on the... 

May directly scavenge O radicals and regenerate a-tocopherol from the a-tocopheroxyl radical Interrupts chain-reaction lipid peroxidation Scavenges singlet oxygen May scavenge O radicals directly regenerates oxidized ascorbic acid... 

Fig. 7) for example measurement of tris(l,10-phenanthroline)cobalt(II/III) show that this redox couple is 230 mV deeper (more positive redox potential) than iodide electrolyte [37]. As a consequence, cobalt electrolytes, and soUd organic hole conductors, have been widely explored. It should be noticed in Fig. 7 that Co(II/III) redox couple stands too deep to regenerate oxidized standard ruthenium bipyridyl dye. Therefore both the dye and the redox couple have been simultaneously optimized for strong performance [99, 100] and this approach has provided large rewards in terms of power conversion efficiency [2]. 

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