The likely relevance of each term of a search-engine query of two or more terms is determined by their deletion probability scores. A silicon oxide-containing layer is formed on the surface of a polyimide layer and a second layer of polyimide is formed on the silicon oxide-containing layer. A path is conceptually traced through the represented structure and an examination is conducted, for each atom, of each possible electronic and bonding state that is consistent with what has come before along the path. Furthermore, the processor device may generate a visual display indicating the presence of the selected metabolites across the group of samples.