Are things besides water used? Like a vacuum or something else? Would the stiffness be dependent on the energy density gradient between what it is embedded in?

Are things besides water used? Like a vacuum or something else? Would the stiffness be dependent on the energy density gradient between what it is embedded in? The technique reminds of those i've seen in sparse eigen decomposition of a matrix, where some non square matrix X is embedded in a larger sparse matrix of zeros of the form: ⎡ zeros(X.n_rows, X.n_rows) X ⎤ ⎣ X.t() zeros(X.n_cols, X.n_cols) ⎦ Except for in this case the larger matrix of zeros would be replaced by a repeated structure. Though I can't help but think that using non zeros would get some weird energy feedbacks (due to the interaction of the protein with the embedding matrix molecules) that would require some renormalizations.