New answers tagged biophysics
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The resolution of an SEM is not set by the electron wavelength, but rather by the size of the electron beam that is scanned over the sample. Imagine you had a flashlight scanning over a patch of ground, and were recording the reflected light intensity, without using any lenses, to reconstruct the surface features -- your resolution would be roughly the spot ...
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This is more than likely better asked in physics SE, however since you contextualized it biologically somewhat I will answer it here.
You are correct in your concern. The Rayleigh Criterion and the associated calculations(Rayleigh Scattering) are talking about the minimum separation of 2 light sources to resolve a given object. From this we are able to ...
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There are (at least) two sides to this story. One is direct DNA damage being caused by UV-B light which happens to have photons with just the right amount of energy to interact with thymine. This has been known, and assumed not just during the 80s, but until the late 2000s to be The One major thing that causes cancer, or trouble in general (there's papers ...
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You're talking about long-wave UV, or UV-A radiation. In the 80s, experts claimed that this was a safe wavelength. Protection against UV-A was not part of sunscreen in the early days. Consequently, UV-A was (and still is) used in tanning beds due to its perceived safety over UV-B. However, a lot of research has been done since.
UV-A is well understood now ...
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