The assemblies of the invention can comprise a fine fiber layer having dispersed within the fine fiber layer an active particulate material. Fluid that flows through the assemblies of the invention can have any material dispersed or dissolved in the fluid react with, be absorbed by, or adsorbed onto, the active particulate within the nanofiber layer. The structures of the invention can act simply as reactive, absorptive, or adsorptive layers with no filtration properties, or the structures of the invention can be assembled into filters that can filter particulate from a mobile fluid while simultaneously reacting, absorbing, or adsorbing materials from the mobile fluid.