Supervisor: Karol Hensel Consultant: -- Title: Effects of atmospheric pressure cold discharge plasmas to bacteria and cell cultures Abstract:
MSc. study Supervisor: Karol Hensel Consultant: -- Title: Electrical discharge in aqueous medium, their biological and chemical effects Abstract: The objective of the work is to investigate pulsed discharges in an aqueous medium (above water surface, in water sprayed by electro-spray, etc) and evaluate their for an inactivation of selected bacteria and spores. The aim is to study not only electrical properties of the discharges, but mainly their bactericidal and chemical effects in air and water. Efficiency of inactivation of bacteria will be compared with chemical changes induced in the water. The production rate of various active species (eg O3, H2O2, NO2-, NO3-, ONOO-) will be examined as well as induced oxidative stress in bacteria by TBARS method.
Bc. study 2011 - 2012
Supervisor: Karol Hensel Consultant: -- Title: Biodecontamination by pulsed electrical discharges Abstract: In the presented work we focus on biodecontamination by low-temperature nonequilibrium plasma produced by pulsed electric discharges in atmospheric pressure air. Pulsed discharges were generated by rotary spark gap high-voltage power supply. The objective was to examine the pulsed discharges and their use for bio-decontamination of gram-positive spore forming bacteria Bacillus cereus, evaluate their efficiency and dependence on various parameters (amplitude and frequency of applied voltage, exposure time) and compare it with the results obtained with direct current power supply. Two types of discharges were tested – spark discharge and corona discharge. The effect of the spark discharge was tested on bacteria in solution by utilizing electrostatic atomization, while spores deposited on the surfaces were subjected to the corona discharge. Bacterial samples were cultivated on Petri dishes and evaluated by plate count method. The results showed that the biocidal effect of pulsed spark discharge was lower compared with the effect of transient spark discharge generated by a direct current voltage. On the other hand, the efficiency of the corona discharge generated by pulsed power supply was found to be 20% higher than one obtained with direct current power, with negative polarity to be more efficicent than positive one. The results demonstrate the positive potential of the pulsed discharge toward the deconamination of bacteria. However, to unequivocally confirm our results and determine the relationship of the efficiency and the amplitude and frequency of the pulses and exposure time, further experiments are needed.