Oxidative assimilation

Rozich, A.F. and Lowe, W.L., Oxidative assimilation treatment of a nitrogen-deficient toxic waste,... 

Doudoroff, M. 1940. The oxidative assimilation of sugars and related substances by Pseudomonas saccharophila with a contribution to the direct respiration of di- and poly-saccharides. Enzymologia 9 59-72. 

The subsequent fate of the assimilated carbon depends on which biomass constituent the atom enters. Leaves, twigs, and the like enter litterfall, and decompose and recycle the carbon to the atmosphere within a few years, whereas carbon in stemwood has a turnover time counted in decades. In a steady-state ecosystem the net primary production is balanced by the total heterotrophic respiration plus other outputs. Non-respiratory outputs to be considered are fires and transport of organic material to the oceans. Fires mobilize about 5 Pg C/yr (Baes et ai, 1976 Crutzen and Andreae, 1990), most of which is converted to CO2. Since bacterial het-erotrophs are unable to oxidize elemental carbon, the production rate of pyroligneous graphite, a product of incomplete combustion (like forest fires), is an interesting quantity to assess. The inability of the biota to degrade elemental carbon puts carbon into a reservoir that is effectively isolated from the atmosphere and oceans. Seiler and Crutzen (1980) estimate the production rate of graphite to be 1 Pg C/yr. 

The NOxTrap can be assimilated to a three-way catalyst7 complemented by a NOz storage function. This system contains two types of precious metals the first one, dedicated to NO, HC and CO oxidation in lean operating mode, will generally consist of platinum or palladium. The second one, dedicated to NOx reduction in rich operating mode, is typically rhodium. Rhodium price spectacularly increases, with a multiplication by three of its value in 2006 (see Figure 7.13)8. 

Fig. 5.7. In green sulfur bacteria and in some archaebacteria, a reverse citric acid cycle is used for the assimilation of C02. It must be assumed that this was the original function of the citric acid cycle that only secondarily took over the role as a dissimulatory and oxidative process for the degradation of organic matter. A major enzyme here is 2-oxoglutarate ferredoxin for C02 fixation. Note that it, like several other enzymes in the cycle, uses Fe/S proteins. One is the initial so-called complex I which has eight different Fe/S centres of different kinds but no haem (see also other early electron-transfer chains, e.g. in hydrogenases).

BARBER, R.D., DONOHUE, T.J., Function of a glutathione-dependent formaldehyde dehydrogenase in Rhodobacter sphaeroides formaldehyde oxidation and assimilation, Biochemistry, 1998, 37, 530-537. 

Taking as an example an ionic oxide MO, this material can be made into a metal-excess nonstoichiometric material by the loss of oxygen. As only neutral oxygen atoms are removed from the crystal, each anion removed will leave two electrons behind, which leads to electronic conductivity. The oxygen loss can be incorporated as oxygen vacancies to give a nonstoichiometric oxide with a formula MOi v, or the structure can assimilate the loss and compensate by the introduction of cation interstitials to give a formula M1+xO. 

Boettcher AA, Targett NM (1993) Role of polyphenolic molecular-size in reduction of assimilation efficiency in Xiphister mucosus. Ecology 74 891-903 Bolwell GP, Butt VS, Davies DR, Zimmerlin A (1995) The origin of the oxidative burst in plants. Free Radical Res 23 517-532... 

In Table 5.4 the contributions of the individual weathering reactions were assigned and combined in such a way as to yield the concentrations of Ca2+, Mg2+, Na+, K+, and H+ measured in these lakes the amounts of silicic acid and aluminum hydroxide produced and the hydrogen ions consumed were calculated stoichiometrically from the quantity of minerals assumed to have reacted. Corrections must be made for biological processes, such as ammonium assimilation and nitrification and the uptake of silicic acid by diatoms. Some of the H4Si04 was apparently lost by adsorption on aluminum hydroxide and Fe(III)(hydr)oxides, but the extent of these reactions was difficult to assess. 

The anhydrides of the organic acids can also be regarded as di-acyhxides (acyl = acid radicle, e.g. CH3.CO = acetyl) and can be thus assimilated to the ethers, or dialkyl oxides. The ethers are amongst the most indifferent of all the conpounds of organic chemistry. Whence, then, comes the great reactivity of the similarly constituted anhydrides The weak point in the anhydride molecule is to be found, not at the... 

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