Data Fitting.    The Equations used to fit the CP experiments are ones that are used to understand the mobility  of gel like systems that have a high degree of water in them\cite{P_rez_Hern_ndez_2012} . The equations used operate the I-I*-S model in which I* denotes protons in close proximity to the S Nucleus.  Within this model, source spins, such as protons, do not have a common spin temperature. The I*-S spin pairs or clusters can be viewed as isolated in a solid and exchanging polarization in an oscillatory manner, damped by the subsequent spin-diffusion contact with the remaining I spins.\cite{Kolodziejski_2010}  This model is especially useful in solids where the system is anisotropic. The equation used for adjusting the experimental curves: \(I\left(t\right)=I_{0^{\ }}\left(1-\frac{T_{CH}}{T_{1P^{ }}^{ }H}\right)^{-1}\left(\exp\left(-\frac{t}{T_{1P^{ }}^{ }H}\right)-\exp\left(-\frac{t}{T_{CH}}\right)\right)\)
From this fit, it is possible to obtain the TCH values which represent the efficiency of magnetisation transfer and that can be used as a guide to describe the rigidity of the system (The higher the magnetisation transfer the more rigid a system is).  The software used for the fitting of the graph was Origin.