Swell-induced surface instability has been observed experimentally in rubbers and gels. Here we present a theoretical model that predicts the critical condition along with a characteristic wavelength for swellinduced surface instability in substrate-confined hydrogel layers. The effect of surface tension is found to be critical in suppressing short-wavelength modes of instability, while the sub...

using environmental-friendly methods in order to remove or reduce oil pollutants and their derivations in the environment are developing. in this study, the biodegrading ability of bacillus subtilis .sp which has been separated from oil-polluted soil was examined. it was revealed that it can reduce surface tension of growth medium and produce bio-surfactant at 37 and 20 degrees centigrade. also...