Multiple degradation mechanisms

Multiple Quantum NMR methods have been used to characterize the results of multiple degradation mechanisms on complex silicone polymer composites. 

However, no correlation was noted between the solvent dielectric and the degradation rate of salmon calcitonin (sCT) in water, DMSO, EtOH, glycerol and PG (Stevenson and Tan, 2000). The lack of correlation was probably due to the multiple degradation mechanisms reacting differently to the solvent dielectric. 

It is extremely important to realize that weathering involves multiple degradation mechanisms. These can be free radical mechanisms (photolytically or thermally... 

It is extremely important to realize that weathering involves multiple degradation mechanisms. These can be free radical mechanisms (photolytically or thermally induced), or acid or base-catalyzed chemistry, as well as physically based mechanisms. This makes weathering a difficult property to study. 

Because of the multiple degradation pathways that may take place at elevated temperature, protein stability monitoring data may not conform to the Arrhenius relationship, and the maximum temperature selected for accelerated stability studies must be carefully selected. Gu et al. [32] described the different mechanisms of inactivation of interleukin-1 (3 (IL-1 (3) in solution above and below 39°C. In this example, the multiple mechanisms precluded the prediction of formulation shelf life from accelerated temperature data. In contrast, by working at 40° C and lower, Perlman and Nguyen [33] were able to successfully extrapolate data from stability studies of tissue plasminogen activator down to 5°C. 

A complete picture of polymer thermal degradation is clouded because multiple reaction mechanisms can be operable for a single polymer at a single temperature, leading to a host of volatile products and residues. Therefore, one has to consider the relative rates of these competing reactions to establish an optimized and controlled binder burnout. 

Apart from these three degradation mechanisms, rearrangements of the fractions formed may take place. A polymer does not undergo only one pyrolysis route always, but multiple routes may be taken simultaneously. The type of reaction is totally governed by the strength of bonds in the molecules. The lowest energy path will be favored. 

Over the service life of a PO, heat-induced degradation can cause losses of multiple desired mechanical properties and inaeased embrittlement. This is shown in Figure 3.3, which compares long-term heat aging (LTHA) of heat-stabilized... 

A peculiar characteristic of our approach is the introduction of models for Basic Security Mechanisms. With this modular approach it is possible to study the performance degradation introduced by any meaningful combination of these (and possible newly built) security mechanisms. By pushing this concept ahead, a more complex type of analysis can be performed on models built by multiple Composed Mechanisms to represent the specification of an existing protocol, such as SSL. In this case an interesting study would be to observe how our models estimate the performance indices, and compare these results to what claimed in the corresponding protocol specifications. 

Random failure (see Chapter VII) Random failures are project specific in the sense that they depend on the process and its use. From lEC 61508 it is found that a failure occurs at a random time, which results from one or more degradation mechanisms. Random failures are mainly caused by physical damage/changes such as wearout, thermal stress erosion/corrosion, etc. These are applicable for hardwires of E/E/PEs in automation systems. The rate of failure of random failures normally cannot be reduced instead for random failures focus should be on their detection and handling. Statistical data handling and treatments can be applied to random failures, hence risks associated with random failure can be calculated. This is not possible in the case of software with systematic faults. Common cause failure (see Chapter VII) This is a kind of fault that causes multiple devices/systems to fail simultaneously. Common cause failure may be random or systematic. This is discussed in Fig. 1/8.3-1 in Chapter I, Chapter Vll, and in Ref. [9]. 

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