A simulation environment for studying transcutaneous electrotactile stimulation

Transcutaneous electrical nerve stimulation (TENS) allows the artificial excitation of nerve fibres by applying electric-current pulses through electrodes on the skin's surface. This work involves the development of a simulation environment that can be used for studying transcutaneous electrotactile stimulation and its dependence on electrode layout and excitation patterns. Using an eight-electrode array implementation, it is shown how nerves located at different depths and with different orientations respond to specific injected currents, allowing the replication of already reported experimental findings and the creation of new hypotheses about the tactile sensations associated with certain stimulation patterns. The simulation consists of a finite element model of a human finger used to calculate the distribution of the electric potential in the finger tissues neglecting capacitive effects, and a cable model to calculate the excitation/inhibition of action potentials in each nerve

Reduction of in vitro growth in Flavobacterium columnare and Saprolegnia parasitica by products containing peracetic acid

Commercial products containing peracetic acid (PAA) are strong disinfectants with a wide spectrum of antimicrobial activity and have been suggested as potential therapeutic agents in aquaculture. The aim of this study was to compare the in vitro reduction of growth on two fish pathogens, Flavobacterium columnare and Saprolegnia parasitica, by seven commercial PAA-containing products. Flavobacterium columnare was exposed to 1, 2, 4, 6, 8 and 10 mg L-1 PAA and S. parasitica was exposed to 0.5, 1, 2, 4, 6, 8 and 10 mg L-1 PAA in petri dishes for 24 h incubation. The reduction of growth was measured in comparison to a PAA-free control. A reduction of the growth was observed for both pathogens with increasing PAA concentration. Hydrogen peroxide (H2O2) possibly has a role in the effectiveness of the products, since products with lower PAA concentrations had a higher concentration of H2O2. The commercial products with a low concentration of PAA and a low PAA:H2O2-ratio were generally more effective against pathogens. The practical application of the products with low PAA concentration should be prioritized. © 2011 Blackwell Publishing Ltd