A fragrance emanating device for freshening atmospheric air has a closed container for accommodating a liquid fragrance composition in its interior, an emanator having a surface open to the ambient air for evaporation of the liquid fragrance composition, and a conduit linking the emanator surface with the liquid fragrance composition in the interior of the container. Devices and methods shown provide a textured surface with properties that provide a high breakdown voltage. Hydrogen sulfide present in the water processing system is removed, and the production of hydrogen sulfide by sulfate-reducing bacteria is eliminated by introducing nitrate into the system, whereby denitrifying microorganisms, using the nitrate, outcompete the sulfate-reducing bacteria for the available carbon nutrients, thus preventing the SRB from producing hydrogen sulfide. The backing material for the fuel cell electrode is specially treated to improve its characteristics. The device includes an optical module featuring an optical source and a first optical sensor that generates a first set of information; a flexible, thin-film pressure sensor that generates a second set of information; and a processing module, configured to receive and process the first and second sets of information to calculate a time-dependent blood pressure value. Transactions of a service provided by each of a plurality of computers to another computer are collected, a matrix of correlations between nodes in the system is calculated from the transactions, and a feature vector representing anode activity balance is obtained from the matrix.