In further correspondence with Doug, he points out this rather odd sentence in Ben Best’s Molecular Mobility at Low Temperature:
Diffusion in a vitrified cryonics patient would presumably not be due to concentration gradients because there should be not concentration gradients.
Surely there can be no concentration gradients only if the whole sample is homogeneous? I’m pretty sure standard cryonics practice doesn’t involve putting the brain in a blender a la Britannia Hospital. I’ll email Best and ask for clarification.