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Plasma Sterilization of Biopolymers
Hantáková, Michaela ; Slámová, Jitka (referee) ; Krčma, František (advisor)
This thesis is dialled to studying the plasma sterilization of biopolymers using lowtemperature non-equilibrium plasma of electrical discharges for the medical applications. The dielectric barrier discharge was generated in atmospheric gases based mixtures at atmospheric pressure. The sodium glass plates were used as dielectric to ensure the discharge operation in the atmospheric pressure glow mode. The effect of various physical parameters of the plasma as well as the stress factors on the sterilization efficiency were studied. The gram-positive bacteria Micrococcus Luteus and gram-negative bacteria Serratia Marcesceus were used as the model organisms under the current study. The bacterial samples were deposited on the Whatman 1 paper as well as on the biopolymer fibres made of P3HB (trade mark Hydal of company Nafigate Corporation). and then exposed to the plasma. The experimental results are evaluated by the available microbiological analysis methods. The samples were after exposed directly to the plasma. Experimental results were evaluated by the accessible microbiologic techniques. The results confirmed the plasma sterilization success; the best results were obtained using sterilization by DBD generated in wet air enriched by oxygen. The detailed research of sterilization using the low temperature non-equilibrium plasma will be a subject of consequent master Thesis.
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Plasmochemical treatment of natural fibres
Demková, Eva ; Mazánková, Věra (referee) ; Přikryl, Radek (advisor)
This bachelor thesis is focused on plasmochemical surface treatment of natural flax fibres using dielectric barrier discharge and silane coupling agent. Treated fibres were used as reinforcement of composite material with an epoxy matrix. Composite materials were prepared manually, by placing saturated fibres into silicone mold. Mechanical properties of composite materials were determined by bending test, tensile test and dynamic-mechanical analysis (DMA). The presence of a silane coupling agent on the surface of the fibre was detected by EDS analysis. SEM method was also used to determine the effect of plasma on the surface of fibres.
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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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Study of plasma activated water application on the total soil microbial biomass content
Poláková, Marianna ; Zlámalová Gargošová, Helena (referee) ; Krčma, František (advisor)
The aim of the diploma thesis was to choose the optimal method for evaluating the content of total microbial biomass in the soil, using plasma-activated water as irrigation, based on literature research. For this purpose, the fumigation-extraction method was chosen, which was evaluated using TOC/TN. The work further focused on the characterization of the physicalchemical properties of plasma-activated water and soil. The rate of decomposition of organic matter in the soil was monitored using the tea bag method, where green and roiboos tea are used to study the rate of decomposition. The content of total water-extractable polyphenolic substances was also determined in green tea. Based on cultivation tests, the presence of soil microorganisms was determined. From the measured data, it was found that the plasmaactivated water does not have a negative effect on the pH of the soil. However, probably as a result of its application, the values of the total microbial biomass in plasma-activated water samples for 10 minutes decreased to the value of (8063±1900) mgkg-1 for TOC and (98±74) mgkg-1 for TN compared to the distilled infusion water, where TOC values were (18068±4186) mgkg-1 and TN (123±10) mgkg-1. .
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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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