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Study of elementary inactivation processes acting during sterilization of procaryotic systems in dielectric barrier discharge
Bittnerová, Zuzana ; Sťahel, Pavel (referee) ; Kozáková, Zdenka (advisor)
Presented master’s thesis is focused on the study of the elementary inactivation processes acting during sterilization of procaryotic systems in dielectric barrier discharge (DBD). Sterilization is an important biomedical and food-industry application and plasma sterilization is one of the methods, which are suitable for sterilization of heat and chemical sensitive materials. Biologically contaminated samples were treated in dielectric barrier discharge operated at atmospheric pressure. The discharge was generated in argon and in nitrogen. The plasma power density was 2725,93 mW cm–3 in argon and 2325,93 mW cm–3 in nitrogen. Gram positive bacteria Bacillus subtilis and gram negative bacteria Escherichia coli were used as a bioindicator. Bacteria were spread onto the surface of Whatman No.1 filtration paper. The influence of UV radiation, reactive species, heat and plasma discharge where the synergistic function of all of the agents was studied. Effects of UV radiation and temperature were studied separately. In order to separate the effect of UV radiation generated by DBD the quartz glass transmitting UV radiation was employed. During the plasma exposition selected samples were covered with the quartz window while other samples were directly exposed to the plasma. Covered samples were exposed to UV radiation and temperature (which cannot be eliminated), samples without quartz window were directly plasma exposed (treated). Results show that for covered samples the lower inactivation was reached than by the samples directly exposed to plasma. When studying the effect of temperature, the temperature between the DBD electrodes was measured by means of a thermocouple. Afterwards the samples were placed in an oven and exposed to the same temperature as was measured between the electrodes. By comparing the results of heat treated samples and plasma treated samples it can be assumed that the influence of the temperature during the sterilization process in DBD is very low. The discharge parameters were studied by means of the Optical Emission Spectroscopy. Plasma treated samples were assessed employing Scanning Electron Microscopy (SEM). Damage of Bacillus subtilis cell wall due to the effect of plasma was observed while no effect of plasma on the structure of filtration paper was detected.
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Study of oxygen and ozone reactions on the surface of solid materials
Staněk, Filip ; Sťahel, Pavel (referee) ; Mazánková, Věra (advisor)
This bachelor’s thesis is concerned with the study of ozone and oxygen on the surface of solid substances. Ozone, one of the forms of oxygen, is a highly reactive molecule that is particularly known thanks to its disinfectant properties. The theoretical part of this work describes the fundamental properties of ozone, the technological applications, the synthesis of this gas and the mechanism of the reactions on the surface of some materials. The experimental part consists of a number of experiments that are focused on the formation and degradation of ozone on the surface of a glass cuvette. Ozone was, for our purposes, generated by DBD, its concentration was measured by absorption spectrometry.
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Thermal stability of Ti/Ni multilayer thin films
Václavík, R. ; Zábranský, L. ; Souček, P. ; Sťahel, P. ; Buršík, Jiří ; Fořt, Tomáš ; Buršíková, V.
In this work, thermal stability and mechanical properties of Ti/Ni multilayer thin films were studied. The multilayer thin films were synthesised by alternately depositing Ti and Ni layers using magnetron sputtering. The thickness of constituent layers of Ti and Ni varied from 1.7 nm to 10 nm, and one coating was deposited by simultaneous sputtering of both targets. Single crystalline silicon was used as a substrate. The effects of thermal treatment on the mechanical properties were studied using nanoindentation and discussed in relation to microstructure evaluated by X-ray diffraction. Annealing was carried out under low-pressure conditions for 2 hours in the range of 100-800 degrees C.
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Study of elementary inactivation processes acting during sterilization of procaryotic systems in dielectric barrier discharge
Bittnerová, Zuzana ; Sťahel, Pavel (referee) ; Kozáková, Zdenka (advisor)
Presented master’s thesis is focused on the study of the elementary inactivation processes acting during sterilization of procaryotic systems in dielectric barrier discharge (DBD). Sterilization is an important biomedical and food-industry application and plasma sterilization is one of the methods, which are suitable for sterilization of heat and chemical sensitive materials. Biologically contaminated samples were treated in dielectric barrier discharge operated at atmospheric pressure. The discharge was generated in argon and in nitrogen. The plasma power density was 2725,93 mW cm–3 in argon and 2325,93 mW cm–3 in nitrogen. Gram positive bacteria Bacillus subtilis and gram negative bacteria Escherichia coli were used as a bioindicator. Bacteria were spread onto the surface of Whatman No.1 filtration paper. The influence of UV radiation, reactive species, heat and plasma discharge where the synergistic function of all of the agents was studied. Effects of UV radiation and temperature were studied separately. In order to separate the effect of UV radiation generated by DBD the quartz glass transmitting UV radiation was employed. During the plasma exposition selected samples were covered with the quartz window while other samples were directly exposed to the plasma. Covered samples were exposed to UV radiation and temperature (which cannot be eliminated), samples without quartz window were directly plasma exposed (treated). Results show that for covered samples the lower inactivation was reached than by the samples directly exposed to plasma. When studying the effect of temperature, the temperature between the DBD electrodes was measured by means of a thermocouple. Afterwards the samples were placed in an oven and exposed to the same temperature as was measured between the electrodes. By comparing the results of heat treated samples and plasma treated samples it can be assumed that the influence of the temperature during the sterilization process in DBD is very low. The discharge parameters were studied by means of the Optical Emission Spectroscopy. Plasma treated samples were assessed employing Scanning Electron Microscopy (SEM). Damage of Bacillus subtilis cell wall due to the effect of plasma was observed while no effect of plasma on the structure of filtration paper was detected.
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APPLICATIONS OF PHOTOCATALYTIC NANOMATERIALS, STANDARDIZATION AND OVERVIEW OF TESTING METHODS
Peterka, F. ; Jirkovský, Jaromír ; Sťahel, P. ; Navrátil, Z.
Successful application of photocatalytic nanomaterials in so called light cleaning is strongly dependent on 1 development of photocatalytic material of new generation to have performance at least one order higher than materials already utilized, 2 development of testing methods as ISO and CEN standards to prove photocatalytic function in broad application field and to support the advertise function. These issues belong to the main objectives of the European COST 540 project "Photocatalytic technologies and novel nanosurfaces materials critical issues", which is understood as European platform to group the existing European teams focusing on the development of photocatalytic nanomaterials and standard photoactivity testing methods In this contribution, overview of state of art of application field and testing methods will be given Information about recently developed new composite photocatalyst material will also be mentioned, but from the point of standard testing.
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Deposition and Characerization of Protective DLC Coatings on Viscoelastic Substrates
Buršíková, V. ; Bochníček, Z. ; Franta, D. ; Sťahel, P. ; Kelar, L. ; Buršík, Jiří ; Klapetek, P. ; Bláhová, O. ; Peřina, Vratislav ; Zemek, J. ; Zajíčková, L.
Deposition and characerization of protective DLC Coatings on viscoelastic substrates.
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