Cyclic damage

Besides frequency effects due to strain-rate hardening and/or specific cyclic damage of the fibrils, there is another typical effect in the case of cyclic loading at high frequencies, namely hysteretic heating. The increase of temperature T near the crack tip, in that case, scales as in Eq. (5)" ... 

ATn is a shift in this critical temperature of brittleness due to cyclic damage. 

The drill collars and particularly their connections are also exposed to cyclic stresses. Subsequently, these are susceptible to fatigue damage, but the changes that may influence failure arc more quickly discovered. 

Cumulative fatigue damage The total of fatigue damage caused by repeated cyclic stresses. 

Recently, it has been demonstrated that coordination vacancies on the surface metal cations are relevant to the unique redox reactivity of oxide surfaces]2]. Oxidation of fonnaldehyde and methyl formate to adsorbed formate intermediates on ZnO(OOOl) and reductive C-C coupling of aliphatic and aromatic aldehydes and cyclic ketones on 1102(001) surfaces reduced by Ar bombardment are observed in temperature-prognunmed desorption(TPD). The thermally reduced 1102(110) surface which is a less heavily damaged surface than that obtained by bombardment and contains Ti cations in the -t-3 and +4 states, still shows activity for the reductive coupling of formaldehyde to form ethene]13]. Interestingly, the catalytic cyclotrimerization of alkynes on TiO2(100) is also traced in UHV conditions, where cation coordination and oxidation states appear to be closely linked to activity and selectivity. The nonpolar Cu20( 111) surface shows a... 

Corrosion Fatigue Corrosion fatigue is a reduction by corrosion of the abihty of a metal to withstand cyclic or repeated stresses. The surface of the metal plays an important role in this form of damage, as it will be the most highly stressed and at the same time subject to attack by the corrosive media. Corrosion of the metal surface will lower fatigue resistance, and stressing of the surface will tend to accelerate corrosion. 

Detection of damage caused to DNA by niclosamide in schistosomiasis was investigated using an electrochemical DNA-biosensor. It showed for the first time clear evidence of interaction of niclosamide with DNA and suggested that niclosamide toxicity can be caused by this interaction, after reductive activation. The electrochemical reduction and oxidation of niclosamide involved the use of cyclic, differential, and square-wave voltammetry, at a glassy carbon electrode. It enabled the detection limit of 8 x 10-7 M [34]. 

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