Acclimatisation phase

Generally, LAS biodegradation processes were previously monitored either as primary biodegradation (a decreasing LAS concentration) or as mineralisation (formation of biomass and/or C02). Both processes have usually been fitted to a first order kinetics, but this approximation is only valid if there has been no prior acclimatisation phase an initial lag phase is usually present in biodegradation tests [4]. Nevertheless, first order kinetic constants may be used for special cases or for a preliminary characterisation of the process. 

However, precise fits require the use of at least second order models, which include three characteristic phases in the biodegradation process [4] (i) an acclimatisation or lag phase (ii) an exponential phase with most of the effective degradation and (iii) a final phase in which the microorganism population is stable and some portion of the substrate could persist (see Fig. 5.3.1(a) [21]). 

Recently membrane lipids from Brassica napus root cells were examined with respect to effects from dehydration-acclimatised plants [59]. It was found that the lipids formed a cubic phase with excess water vmder physiological conditions. On heating, this phase transformed directly into a reversed micellar phase. The transition was also foxmd to coincide with the temperature limit of survival of the plant. Also after repeated water-deficient stress, a cubic phase is formed in excess water, although there are differences in the phase properties compared to lipids from membranes of plants grown normally. 

Acclimatisation, marking of test areas Measuring of base values TEWL and BF Application of irritants on test areas a-i on right forearm in test phase 1 and on both forearms in test phase 2 Phase of irritation Removal of test plasters... 

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