The web of the invention can comprise a super absorbent layer that can act as an moisture sensitive fuel shut-off valve, absorbent, adsorbent or reactant. The web of the invention can comprise a super absorbent fabric or layer made of a superabsorbent particle or fiber. The web can comprise a nanofiber layer having dispersed within the nanofiber layer a super absorbent particulate and optionally a second particulate material that can act as an absorbent, adsorbent or reactant. Fluid, gas or liquid, that flows through or by the assemblies of the invention can have any gas, liquid or solid material dispersed or dissolved in the fluid interact with the super absorbent particulate. If needed these materials can also react with, be absorbed by, or adsorbed onto, the active particulate within the nanofiber layer. The structures of the invention can act simply as flow-by 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 in a flow-through mode while simultaneously reacting, absorbing, or adsorbing materials from the mobile fluid.