Damage profiles accumulation

Distribution, including accumulation of an absorbed substance, will be the same irrespective of the route of administration. However, distribution and accumulation at the site of apphcation (inhalation, oral, dermal) may depend on the route of administration. In such cases, local accumulation may occur and may be responsible for tissue damage. In these cases, systemic toxicokinetics of the substance may be of limited relevance for the risk assessment. It is generally not cmcial for risk assessment to determine the precise tissue distribution profile for a substance. In certain special cases, however, specific tissue distribution studies may assist or even be essential for the interpretation of available toxicological data. For example, it may be of interest to know whether the substance will cross the blood-brain barrier, the placenta barrier, or will accumulate in specific tissues. 

In this section we will review the current knowledge of ion damage accumulation and chemical profiles in as-implanted single-crystal SiC. We will investigate the effects of the postimplant annealing process in Section 4.3. Results for the 4H- and 6H-SiC polytypes will also be presented. 

The intention of this contribution is to calculate with a general model the damage progression for different load histories, independent from specific load coUective-based experiments. One novel aspect is to conclude from failures of individuals of a considered set of systems used with individual load profiles to the underlying, problem/application-specific damage accumulation relation. This is done by a nonlinear mathematical model, calculating the caused damage due to the applied stress. 

In this modified application of the damage accumulation hypothesis, degradation prior to reaching state 1 is not summed up to evaluate failure. Instead, the aging progress of individual intervals is related to the reference temperature and a reference time is calculated that corresponds to each of them. This reference time at reference temperature now results in degradation comparable to that in the time-temperature profile [104]. 

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