Treatment effects/differences changing parameters

Another simple approach assumes temperature-dependent AH and AS and a nonlinear dependence of log k on T (123, 124, 130). When this dependence is assumed in a particular form, a linear relation between AH and AS can arise for a given temperature interval. This condition is met, for example, when ACp = aT" (124, 213). Further theoretical derivatives of general validity have also been attempted besides the early work (20, 29-32), particularly the treatment of Riietschi (96) in the framework of statistical mechanics and of Thorn (125) in thermodynamics are to be mentioned. All of the too general derivations in their utmost consequences predict isokinetic behavior for any reaction series, and this prediction is clearly at variance with the facts. Only Riietschi s theory makes allowance for nonisokinetic behavior (96), and Thorn first attempted to define the reaction series in terms of monotonicity of AS and AH (125, 209). It follows further from pure thermodynamics that a qualitative compensation effect (not exactly a linear dependence) is to be expected either for constant volume or for constant pressure parameters in all cases, when the free energy changes only slightly (214). The reaction series would thus be defined by small differences in reactivity. However, any more definite prediction, whether the isokinetic relationship will hold or not, seems not to be feasible at present. 

An additional study reported age-dependent effects. Lakshmana and Raju (1994) found that oral treatment of rat pups with endosulfan from postnatal days 2-10 resulted in changes in the concentration of noradrenalin, dopamine, and serotonin in various brain areas that differed either in magnitude or direction from changes seen in pups treated from postnatal days 2-23. While the results from this study do not necessarily indicate that neonates are more sensitive to the toxic effects of endosulfan, they do show that the duration of exposure in neonates is an important parameter to consider. 

Statistical analysis is a very useful tool for evaluating the effects of treatment on many developmental and reproductive toxicity parameters. For some parameters, such as maternal body weight changes, fetal weight, and horizontal activity in an open field, the comparison to the concurrent control is the primary consideration and, assuming adequate group size, the investigator relies heavily on the results of appropriate statistical analyses to interpret differences from control. 

It was observed elsewhere that plasma treatment of polymer macromolecules results in their cleavage, ablation, alterations of chemical structure and thus affects surface properties e.g. solubility [75]. The effects of the treatment in Ar plasma on the surface properties of PE were examined in [72]. The parameters of the plasma discharge (240 s, 8.3 W power) were chosen, on the basis of our previous experiments [70-74,78], to guarantee the most pronounced changes of polymer surface. Mean thickness of the ablated PE layer was calculated from the weight difference measured by gravimetry. By Ar plasma (8.3 W, 240 s) 30 8 nm thick surface layer is ablated and thickness of the surface layer removed from plasma-modified PE by 24 hour water etching is 21 5 nm [78]. 

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