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The full material characteristics in the Preisach model of hysteresis is a two-dimensional weighting function. It can be determined experimentally from systematic measurement of partial hysteresis loops followed by derivation of their decreasing parts. Because of measurement errors, the derivation is not correct. Nevertheless, basic material features can be obtained either from incomplete measurement that uses the Preisach triangle respecting the measurement errors. The non-uniform grid in the Preisach model is used in order to get approximately the same steps in changes of the flux density. Simulation shows that this withdrawal of some rows and columns does not change the hysteresis loop considerably, only the steps of the flux density may be higher.

This article presents the sterilization of bacteria using cavitation bubbles. Cavitation generated by ultrasound creates a cavitation cloud. Therefore is more advantageous to generate the cavitation bubbles by laser-induced breakdown, because it is possible to generate individual bubbles for the purpose of study single impact and physical mechanism of acting. The cavitation bubble is generated by a Nd: YAG 532nm laser beam, a short 10ns pulse. Here, we used optics to focus the laser beam and a high-speed camera to visualize characteristics the bubble. We used the method of long-distance microscopy and shadowgraph lightening for the visualization. We used the particle image velocimetry (PIV) method to determine the interaction of the bubble with the surrounding liquid and solid surface. The main goal of the research is to use cavitation to sterilize bacteria and biofilm in impact of single bubble collapse on living cells.