Degradation by oxidations

Ultra-sound emissions typically occur when male rodents are exposed to female odours or altricial neonates to maternal sources (Whitney, 1974 Conely and Bell, 1978). Without the VNO, sexually inexperienced male mice do not utter emissions at ultra-high frequencies (UHF), whereas those with prior experience vocalise after VN-x, as discussed above (Chap. 5). Female mouse urine contains a unique UHF-eliciting component which is non-volatile but ephemeral (Sipos et al., 1995). The signal is degraded by oxidation and disappears within 15 to 18 hours of deposition. Direct contact with freshly voided urine must occur before males will vocalise (sexually experienced or inexperienced). At least one of the olfactory systems is needed for UHF to be elicited by fresh urine complete deafferentation abolishes the response (Sipos et al., 1993). Exposure to females permits UHF to be elicited by other than chemical cues (Labov and Wysocki, 1989). Nocturnal or cryptic species conceivably use ultrasound to advertise male presence whether this is to deter other males or assist with female location is unclear. 

Sipos M., Alterman L., Perry B., Nyby J., et al. (1995). An ephemeral pheromone of female house mice — degradation by oxidation. Anim Behav 50, 113-120. 

Oxidation parameters can be used instead of mechanical strength to measure very early stages of degradation by oxidation [14, 15]. 

Smoking of a single cigarette yields peak plasma levels in the range of 25-50 ng/mL. The effects described on p. 110 become evident When intake stops, nicotine concentration in plasma shows an initial rapid fall, reflecting distribution into tissues, and a terminal elimination phase with a half-life of 2 h. Nicotine is degraded by oxidation. 

Because of the prevalence of degradation by oxidation, antioxidants are generally added. These antioxidants are generally compounds that readily react with free radicals or those that may act to lessen the effects of enticers such as UV radiation. 

Histamine is rapidly degraded by oxidative de-samination by the diaminooxidase histaminase, acetylation of the NH2-group, methylation of the ring and oxidation of the methylhistamines by the mono-aminoxidase. The main metabolites are the N-methyl-imidazole acetic acid and the imidazole acetic acid. Histamine interacts with at least four different specific receptors Hi to H4 (see Table 1). 

Fuel degradation by oxidation is a common cause of fuel stability problems. Gasoline, jet fuel, diesel fuel, and heating oil are all susceptible to oxidative degradation. The following methods can be used to help determine the oxidative stability of fuels ... 

This test method is commonly utilized throughout the world to rapidly determine the oxidative stability of distillate fuel. Although not as effective at predicting the long-term stability of distillate fuel as ASTM D-4625, this method is useful for measuring the resistance of fuel to rapid degradation by oxidation. Metal catalysts such as copper and iron are sometimes added to the fuel to further accelerate... 

Predicting Atmospheric Degradation by Oxidation and Photolysis 469 Table 16.3 HYDROWIN training set statistics and linear free energy relationship (LFER) equations. 

Unsaturated polyesters can undergo degradation by oxidation of their aliphatic segments, decarboxylation of esters and partial depolymerization of polystyrene chains. 

Anhydride-cured epoxies can be also degraded by oxidation (leading to very easily hydrolysable anhydride groups) ... 

The reactivity of unsaturations with ozone has been applied to produce structures which allow subsequent degradation of materials by ozonolysis. In this way, Peters et al. [105] prepared polyurethanes using novel unsaturated diisocyanates which can be degraded by oxidative cleavage of the double bonds. 

Direct connective tissue macromolecule degradation by oxidants... 

Another essential requirement for the photocatalyst is its resistance to reactions at the solid/liquid interface that may result in a degradation of its properties. These reactions include electrochemical corrosion, photocorrosion, and dissolution (Morrison, 1980). A large group of photocatalysts with suitable semiconducting properties for solar energy conversion (CdS, GaP, etc.) are not stable in the water-oxidation reaction because the anions of these materials are more susceptible to oxidation than water, causing their degradation by oxidation of the material (Ellis et al., 1977 Williams, 1960). 

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