ABSTRACT
The transport of material through a membrane is one of the basic processes in the life of organisms. The diffusion coefficient depends on the size of the penetrant molecule, and the fractional free volume of the penetrant and the membrane. The membranes in the living organisms are made of lipid molecules. Their hydrophilic ends are concentrated in two surface layers, one on each side of the membrane. The relaxation or even the breakage of some polymer chains may enormously enhance the transport of the diffusing molecules through the almost polymer free channels thus formed in the relaxed membrane. The penetrant molecules are absorbed in the membrane only in the case in which space for their accommodation can be created. If the concentration is too small the nuclear magnetic resonance signal is not strong enough to be recorded over a sufficiently long period of time above the unavoidable noise level.
