β Scribed by J.T. Daycock; A. Darke; D. Chapman
No coin nor oath required. For personal study only.
Proton spin lattice relaxation (7"1) measurements have been made with a number of lecithinwater systems.
In most cases a Tj minimum is observed at a temperature below the alkyl chain melting temperature. The temperature at which this T~ minimum occurs depends upon the chain length of the lecithin and the concentration of heavy water. Above the chain melting temperature all the systems studied show a similar behaviour, with the T1 increasing exponentially with temperature and giving a similar activation energy in each case.
Throughout the temperature range studied only a single 7'1 is observed, indicating that spin diffusion is taking place and enabling the whole molecule to relax via a single relaxation mechanism. Reasons are advanced for considering that this relaxation mechanism arises from the motion of the choline group.
π SIMILAR VOLUMES
## Abstract Spinβlattice relaxation rates of water protons in hydrated immobilized lysozyme are measured as a function of magnetic field strength. The dependence of water relaxation versus hydration is presented from 35 to 55% by weight water content. The waterβproton relaxation is directly coupled
The molecular motion of a nitroxide free-radical probe in lecithin and lecithin-water systems has been studied as a function of temperature. In the lecithin-water system a significant decrease in the motion of the probe is observed on crystallisation of the hydrocarbon chains. At temperatures above