Passivity self-activation

The anodes are generally not of pure metals but of alloys. Certain alloying elements serve to give a fine-grained structure, leading to a relatively uniform metal loss from the surface. Others serve to reduce the self-corrosion and raise the current yield. Finally, alloying elements can prevent or reduce the tendency to surface film formation or passivation. Such activating additions are necessary with aluminum. 

A source of Aphrodisin which is present in an alternate emission vehicle is that of female saliva. Self-grooming spreads the signal on flank fur and passive or active deposition may then leave traces during contact with burrow walls. The sebaceous flank glands being inconspicuous (and dimorphic) in the female do not play a significant role in advertising her presence. 

There are no passive or active methods for mitigating the blast or missile effects of a BLEVE-type explosion after the BLEVE has taken place, other than the self-preservation actions of persons turning and running away if there is any visual (speed of light) warning. However, the primary cause of BLEVE is fire exposure, and several precautions can be taken during fire-fighting to minimize the risk of injury from BLEVE ... 

Beginning the potential scan in the passive region and scanning in cathodic direction a steep decrease of the current density is observed at the Flade potential caused by the dissolution of the passive film. The same potential is observed if the passive current is switched off and before the potential jumps to the active region. This effect is called switch-off activation or self-activation. The activation time depends on the thickness and the dissolution rate of the oxide film. Therefore the Flade potential is also called activation potential. 

Fig. 3.5 Self assembled chitosan nanoparticles for passive or active cancer targeting [129, 130]...

Buksha, Yu K., The Status of Work in the USSR on Using Self-protection Features of Fast Reactors, of Passive and Active Means of Shutdown and Decay Heat Removal Systems, Proc. of the IAEA Specialists Meeting on Passive and Active Safety Features of LMFBRs, Oarai, Japan, 1991. 

Beyond programmed systems the next step in complexity consists in the design of chemical learning systems, systems that are not just instructed but can be trained, that possess self-modification ability and adaptability in response to external stimuli (Figure 8). Adaptation can be passive or active. The former is illustrated by the reversible interconversion of pentameric and hexameric circular helicates as a function of the anions present in the medium [21]. The latter implies a learning process. 

The use of the potentiostatic method has helped to show that the process of self-passivation is practically identical to that which occurs when the metal is made anodically passive by the application of an external current" . The polarisation curve usually observed is shown schematically in Fig. 19.37a. Without the use of a potentiostat, the active portion of the curve AB would make a sudden transition to the curve DE, e.g. along curve AFE or AFD, and observation of the part of the curve BCDE during anodic polarisation was not common until the potentiostat was used. 

We have found that dendrimers can be used to encapsulate active moieties, thereby preventing them from interacting. This passivation effect limits inter-molecular interactions such as self-aggregation and molecular clustering. We also found that dendrimers can be made dipolar. This asymmetry in molecular orientation enables dendrimers to be used in NLO. In this chapter we describe our application of dendrimers to lasers and NLO. 

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