Aluminum behavioral effect

Numerous mechanistic studies of aluminum neurotoxicity have been performed, but the main sites of action have not been discerned as discussed in Section 2.4.2 and by Strong et al. (1996). Additional studies could help identify a single unifying mechanism that can explain and reconcile the wide variety of pathological, neurochemical, and behavioral effects of aluminum induced by oral exposure and in various model systems (e.g., intracerebral and intracistemal administration), but these kinds of studies are unlikely to better characterize neurotoxicity NOAELs and LOAELs relevant to MRL assessment. The relationship between aluminum exposure and neurotoxicity is an active area of research. 

Bowdler NC, Beasley DS, Fritze C, et al. 1979. Behavioral effects of aluminum ingestion on animal and human subjects. Pharmacol Biochem Behav 10 509-512. 

Misawa T, Shigeta S. 1992. Behavioral effects of repeated aluminum administration in the rat. Tokai J Exp Clin Med 17 155-159. 

The behavioral effects of aluminum have not been extensively studied. Crapper and Dalton described a number of behavioral changes in cats after infusion of aluminum chloride into the brain. 

Release waves for the elastic-plastic regime are dominated by the strength effect and the viscoplastic deformations. Here again, quantitative study of the release waves requires the best of measurement capability. The work of Asay et al. on release of aluminum as well as reloading, shown in Fig. 2.11, demonstrates the power of the technique. Early work by Curran [63D03] shows that limited time-resolution detectors can give a first-order description of the existence of elastic-plastic behavior on release. 

It appears that the observed breakdown must be explained in terms of the transient behavior of stress-induced defects even though the stresses are well within the nominal elastic range. In lithium niobate [77G06] and aluminum oxide [68G05] the extent of the breakdown appears to be strongly influenced by residual strains. In the vicinity of the threshold stress, dielectric relaxation associated with defects may have a significant effect on current observed in the short interval preceding breakdown. 

Fig. 8.9. The strongly exothermic reaction of hematite and aluminum mixtures shows effects strongly dependent on shock conditions that vary from no reaction to a strong, vigorous reaction. The observed behavior indicates that the heat of reaction does not play a dominant role in initiation of reaction.

An overview of the superplastic behavior of aluminum alloys to demonstrate the grain-size effect is depicted in Fig. 1, in which the quantitative relation between the logarithm of the optimum strain rate for superplastic flow and the grain size (plotted as the logarithm of reciprocal grain size) is clearly shown [4]. The slope of the curve in Fig. 1 is noted to be about 3. 

Most commercial uses of aluminum require special properties that the pure metal cannot provide. The addition of alloying elements imparts strength, improves formability characteristics, and influences corrosion resistance properties. The general effect of several alloying elements on the corrosion behavior of aluminum has been reported by Godard et al. (2) as follows ... 

Ionization energies deviate somewhat from smooth periodic behavior. These deviations can be attributed to screening effects and electron-electron repulsion. Aluminum, for example, has a smaller ionization energy than either of its neighbors in Row 3 ... 

The behavior of aluminum in neutral and weakly alkaline solutions resembles the behavior of magnesium, but the negative difference effect is much less pronounced at aluminum. The steady-state potential of aluminum is approximately 1V more positive than the thermodynamic value. Yet unlike magnesium, aluminum will not passivate in strongly alkaline solutions, but undergoes fast dissolution to soluble aluminates. 

A consideration of the electrochemical behavior of the large variety of aluminum alloys used in practice surpasses by far the scope of this chapter. Nevertheless, we consider it useful to review here the effect of some elements that have a profound effect on this behavior. 

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