Highly ordered or crystalline biological macromolecules become severely
damaged and structurally disordered after a brief electron exposure.
Evidence that damage and structural disorder are occurring is clearly given
by the fading and eventual disappearance of the specimen's electron
diffraction pattern. The fading and disappearance of sharp diffraction spots
implies a corresponding disappearance of periodic structural features in the
specimen. By the same token, there is a oneto- one correspondence between
the disappearance of the crystalline diffraction pattern and the
disappearance of reproducible structural information that can be observed in
the images of identical unit cells of the object structure.
The electron exposures that result in a significant decrease in the
diffraction intensity will depend somewhat upon the resolution (Bragg
spacing) involved, and can vary considerably with the chemical makeup and
composition of the specimen material.
Performance Analysis of a Non-identical Unit System with Priority and Weibull Repair and Failure Laws