Oxidative attack, bacterial degradation

MID of Concrete by Bacteria When it comes to concrete structures, the mode of attack by bacteria can be grouped as direct or indirect. In direct degradation attack, the bacterially produced hydrogen sulfide reacts with lime cement, whereas the indirect mode occurs by generating sulfuric acid through the oxidation of sulfur, which in essence is similar to their synonyms as mentioned in Section 4.5.I.I.3.I. 

However, several bacterial strains, capable of degrading toluene and to oxidize nitrobenzene, have been isolated. While in cells of Pseudomonas putida FI and Pseudomonas sp. strain JS150, a dioxygenase medianism converts nitrobenzene into the corresponding dihydrodiol, in other microorganisms, a monoo genase is instead responsible for the initial attack on nitrobenzene [55]. 

Definition Starch etherified with propylene oxide, rendering it more resist, to thermal degradation and bacterial attack... 

The effect of such an additive on the UV degradation of polyethylene is shown in Fig. 3 which shows carbonyl formation in the polymer with time in the presence and absence of additive. It can be shown that carbonyl formation correlates directly with the physical properties of the polymer which rapidly loses strength and embrittles. Embrittlement and fragmentation are particularly rapid in the case of the more crystalline polymers which crumble even under the influence of wind and weather (see Fig. 4). The polymer particles so formed are chemically modified by oxidation to be now subject to attack by normal bacterial action and it is anticipated that these will quickly become part of the soil. 

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