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Plasmachemical preparation of polymer layers based on 2-ethyl-2-oxazoline and their diagnostics
Podzemná, Erika ; Menčík, Přemysl (referee) ; Mazánková, Věra (advisor)
The bachelor’s thesis deals with deposition of thin polymer layers on 2-ethyl-2-oxazolin basis in a dielectric barrier discharge in a nitrogen atmosphere. Polyoxazolines are characterized by good antibacterial effects in general, which make them a suitable material for medical applications. After preparing of the layers. Their properties were studied using three methods. The first were antibacterial tests, which unfortunately did not confirm the above written properties. Furthermore, the free surface energy of the layers, from which it could be inferred that the surfaces were hydrophilic, was determined by measuring contact angles. The scanning electron microscopy showed the surface of the layers as well as the elemental composition thanks to the connected X-ray detector.
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Study of Sterilization Effects Initiated by Dielectric Barriere Discharge
Slámová, Jitka ; Pekárek, Stanislav (referee) ; doc. RNDr. Karol Hensel, Ph.D., oponent (referee) ; Krčma, František (advisor)
The overall goal of the presented dissertation thesis was to study the sterilization efficiency of dielectric barrier discharge operated at atmospheric pressure. The fungi Aspergillus niger, gram-positive bacteria Bacillus subtilis and in some experiments also gram-negative bacteria Escherichia coli were used as a bio-indicator enabling to evaluate the effect of plasma assisted microbial inactivation. The samples of microorganism were placed on paper Whatman 1 or PET foil and exposed to plasma. The plasma was generated in argon, nitrogen, synthetic dry/humid air with frequency up to 10 kHz and plasma power density in the range of 1,2-2,9 W/cm3 (according to the process gas). The influence of process gas, plasma power density, plasma exposition time, type of microorganism and material of the substrate on the sterilization effect of dielectric barrier discharge was evaluated. Furthermore the contribution of each single mechanism (UV radiation, temperature and reactive species) to the sterilization effect of plasma and influence of gas humidity was evaluated. The DBD was analysed by means of optical emission spectroscopy, thermocouple was used to measure temperature during a sterilization process. In order to verify the mechanical damage of the microbial cell or the substrates during the plasma process the samples were studied by scanning electron microscopy. Generally, on the basis of experimental results, at increasing treatment times, the remaining number of spores (CFU) decreased. Similarly at increasing the plasma power input, the sterilization rate increased. When sterilising the spores of A. niger in plasma using different process gasses, the efficiency of plasma sterilization decreased as follows: argon, humid synthetic air, nitrogen and dry synthetic air. The results observed in argon plasma using different microorganism demonstrated that the sensitivity of vegetative cells resp. spores to DBD decreased as follows: A. niger spores, B. subtilis vegetative cells, E. coli vegetative cells and B. subtilis spores. Simultaneously results observed for sterilization of spores and vegetative cells of B. subtilis and A. niger demonstrated that the spores are generally more resistant to plasma than are the corresponding vegetative cells. Combining the results of contribution of each single mechanism, optical emission spectroscopy and inactivation characteristic it was found out that the reactive species significantly contribute to the plasma sterilization in all process gasses. Furthermore the inactivation process can be partly assisted by UV radiation and also the temperature can contribute in limited extent to inactivation process in some gasses. The contribution of UV radiation to the plasma sterilization decreased as follows: nitrogen, argon, dry syntetic air and humid syntetic air. Moreover it was found out that the contribution of each single mechanism can be species dependent, this is due to the different response of microorganism to the unfavorable external conditions. SEM analysis of the substrates prooved the etching actions of the plasma generated in all process gasses on the surface of the PET foil. The several minute plasma exposition of the PET foil resulted in the occurence of the „hole corrosion“ on the PET surface. Contrary to these there were no visible changes observed in the paper structure.
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Study of plasma activated water influence on soil microorganisms
Lungová, Tereza ; Šimečková,, Jana (referee) ; Krčma, František (advisor)
The bachelor thesis deals with the effects of plasma activated water on microorganisms found in the brown earth sample. The theoretical part is divided into two parts. The first part focuses on the analysis of soil and microorganisms living in it. The second part deals with the general properties of plasma and the formation of plasma-activated water. In the experimental part of this work, plasma-activated water was applied to the leachate of soil microorganisms and also directly to a selected soil sample in various concentrations. Subsequently the effect on the viability of soil microorganisms and the composition of soil microorganisms was observed. Based on the results from the practical part, it was found that plasma-activated water has no significant positive or negative effect on soil microorganisms. For this reason, it will be necessary to focus on specific types of microorganisms in further research.
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Surface modification of biomaterials in the dielectric barrier discharge
Maruniak, Marek ; Přikryl, Radek (referee) ; Mazánková, Věra (advisor)
The work deals with the treatment of surfaces of various polymeric biomaterials using a plasma generated at atmospheric pressure. Plasma is generated between two electrodes among which is inserted dielectric material. By using this type of discharge, the difference of treated material surface quality is being examined, ie. surface energy and contact angle according to the time of processing. Evaluation of the results of surface analysis was performed by the method of measuring the contact angle and surface energy using the apparatus See System. The goal was to compare the surface quality change, before and after processing in the plasma, as also its dependency on the time of aging. The results differs according to the type of material.
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Study of elementary inactivation processes acting during sterilization of eucaryotic systems in dielectric barrier discharge
Vojkovská, Hana ; Machala, Zdenko (referee) ; Kozáková, Zdenka (advisor)
This diploma thesis is focused on studying of the effect of the dielectric barrier discharge (DBD) on eucaryotic microorganisms. Plasma sterilization is considered to be an alternative method to conventional sterilization processes. Contrary to standard decontamination methods it doesn´t stress exposed material by heat, pressure and chemicals. Plasma acts on eucaryotic and procaryotic systems by means of synergy of three inactivation mechanisms. They are various reactive species, UV radiation and heat. The Aspergillus niger has been chosen as a bio-indicator enabling to evaluate the effect of plasma assisted microbial inactivation. Plasma was generated in dielectric barrier discharge (DBD) at atmospheric pressure. Nitrogen and argon were used as working gases, paper and PET foil were used as carrying media. The influence of various working conditions on the sterilization effect was studied. Namely it was the influence of plasma exposition time, plasma power density, the type of operating gas and type of supporting medium. The effect of UV radiation in combination with temperature, temperature and direct plasma were studied separately. According to our results the efficiency of DBD increases with plasma power density, resp. plasma exposition time. When comparing sterilization efficiency of nitrogen and argon operating at the same conditions, the higher sterilization effect was observed in argon. The influence of the carrying medium on sterilization effectiveness was proved. It was caused by the different structure of surface. It was found out, that in our experimental setup the active species are probably the main inactivation mechanism. The influence of temperature on inactivation of microorganisms was negligible. The combination of UV radiation and temperature reached the decontamination level about 2 orders. The discharge parameters were studied by means of optical emmision spectroscopy. Scanning electron microscopy enabled to evaluate possible damage of exposed materials through DBD.
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Comparison of organic dye decomposition in various plasma systems
Dotsenko, Anastasia ; Králová, Marcela (referee) ; Kozáková, Zdenka (advisor)
This bachelor thesis deals with the comparison of the degradation of organic dyes (namely: Saturn Red L4B (Direct Red 79) and Indigo Carmine (Acid Blue 74)) in different plasma systems and the general characteristics of the optical emission spectrometry of a microwave plasma nozzle. It briefly summarizes basic information about plasmas and the processes involved. The theoretical part focuses on basic information about plasmas and their processes, basic information about dyes and their degradation methods. Plasma contains a number of active particles such as hydroxyl radicals, nitrogen oxide radicals, excited nitrogen molecules, atomic nitrogen, argon and oxygen. All these particles, together with photons generated by the plasma, are useful in environmental applications. The experimental part focuses on treating a sample of model dyes in selected plasma systems generating plasma above the liquid surface (microwave surface wave discharge, dielectric barrier discharge with liquid electrode) or below it (plasma nozzle in liquid) and evaluating their decomposition rate. Characterization of the distribution of active particles along the plasma axis of a high frequency plasma jet in argon and determination of the conditions in the plasma with respect to the environmental applicability of the system.
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Application of plasma and plasma activated water in cosmetics
Kocianová, Magdaléna ; Tarabová,, Barbora (referee) ; Kozáková, Zdenka (advisor)
This diploma thesis is focused on the study of the inhibitory effects of the cold atmospheric pressure plasma on the grampositive, anaerobic, non-sporulating bacteria Propionibacterium acnes. The treatment was carried out by a direct application of plasma, indirectly (using plasma-treated liquids) and also in their combination. The plasma sterilization process is fast, effective, non-toxic, environmentally friendly, cost-effective and safe not only for the operating staff, but especially for the patient. The experimental part focuses on the study of the direct application of plasma. Two plasma devices for the generation of microwave plasma were used. One of them was a unipolar microwave discharge torch with direct gas supply and the other was a microwave discharge with a surface wave. Discharges were generated in argon with a flow rate of 5 Slm, at a power of 9 W and 12 W. The work also deals with the indirect treatment using plasma-treated liquids. These were prepared using the pinhole discharge and the dielectric barrier discharge. In the last part, combined treatment using plasma-treated liquid and direct plasma treatment was studied. From the achieved results, it can be concluded that the sterilization effects of the plasma and the plasma-treated liquids on the Propionibacterium acnes were confirmed.
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Characterization of plasma activated water for biomedical applications
Šindelková, Kateřina ; Dzik, Petr (referee) ; Kozáková, Zdenka (advisor)
The aim of this master thesis is to characterize plasma activated water (PAW) prepared in various plasma systems using direct and indirect interaction of plasma with liquid or its surface. Plasma was generated by electric discharges at atmospheric pressure. The prepared plasma-activated water was studied with respect to its use in biomedical applications. The theoretical part deals with plasma activated water. It contains a description of the PAW preparation, its characterization in terms of produced particles or its physico-chemical properties. Also, methods for antimicrobial activity estimation or colorimetric determination of produced particles are described in this section. In the experimental part of this work, the types of discharges that were used for the PAW preparation and their comparison are presented. Two types of liquids were selected for the activation, namely distilled and tap water. Subsequently, concentrations of selected reactive particles in PAW (hydrogen peroxide, nitrates and nitrites) produced in three different plasma systems were determined. Besides the comparison of reactive particles production in various systems, their time stability was studied as well. Over time after the PAW preparation, the values of active particles concentrations have changed due to mutual interactions between the particles. Mainly, nitrites were oxidized to nitrates or vice versa depending on the PAW type and other conditions. Part of the work was also monitoring selected physical properties of PAW, namely pH value and specific conductivity. It has been found that PAW does not retain its activated properties for too long, depending on the type of preparation and methods of storage. Therefore, one of the important goals of this work was to determine and compare suitable storage conditions for PAW with respect to its potential biomedical applications.
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Modification of polymeric substrates by means of non-equilibrium plasma
Kuzminova, Anna ; Kylián, Ondřej (advisor) ; Čech, Vladimír (referee) ; Novák, Stanislav (referee)
Title: Modification of polymeric substrates by means of non-equilibrium plasma Author: Anna Kuzminova Department: Department of Macromolecular Physics Supervisor of the doctoral thesis: doc. RNDr. Ondřej Kylián, Ph.D. Abstract: Processing of polymeric materials by means of non-equilibrium plasma is a topic that reaches increasing attention, which is due to the wide range of possible applications. As an example can be mentioned processing of polymeric foils used for food packaging, where plasma treatment enables to improve their functional properties (e.g. increase their printability or enhance their barrier properties). In the frame of this PhD. thesis two different strategies suitable for the modification of polymeric materials were followed. The first one was based on treatment of polymers by atmospheric plasma. The main attention was devoted to the investigation of influence of atmospheric pressure plasma on surface properties of 8 commonly used polymers, namely on their chemical composition, morphology and wettability. In addition, it was observed that plasma treatment causes also alteration of their mechanical properties, may lead to their substantial etching and in some cases improves their biocompatibility. The second studied strategy was based on coating of polymers with thin functional...
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