The structure (102, 302, 402, 502, 602, 702, 802, 902) comprises one or more segments (404, 604) having axially oriented substantially parallel fluid flow passages (110, 304, 410, 510, 610,710,810,910); cell walls (112, 312, 412, 512, 612, 712, 812, 912) between adjacent fluid flow passages, each cell wall having at least two opposite cell wall surfaces, and comprising (in or on a cell wall surface) at least one active compound that can interact with a fluid contained within or passed through the passages; and a plurality of axially continuous, axially oriented, filaments (114, 314, 414, 514, 614,714, 814,914) that are thermally and/or electrically conductive for transfer of thermal energy from the active compound. According to the invention the filaments are embedded within the cell walls in direct contact with the active compound on or in the cell wall surface, and can transfer thermal energy between the active compound and the conductive filaments.