Fig. 2.

Important aspects of the empirical network. (A) The empirical network with nodes scaled according to their degree (i.e., number of links) and colored by material type as indicated in the legends. Five material types with high node degrees are indicated for each class, PM and DOM. Link widths are proportional to the number of experiments using the linked combination. (B) Distribution of the number of DOM or PM types studied with any given PM or DOM, respectively (node degrees). (C) Distribution of the number of experiments conducted per each unique combination of DOM and PM (link weights).