National Repository of Grey Literature 131 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Interaction of non-thermal plasma at atmospheric pressure (CAPP) with non-pathogenic bacteria
Chobotská, Barbora ; Brázda, Václav (referee) ; Kozáková, Zdenka (advisor)
The subject of this bachelor thesis is the study of decontamination effects of cold atmospheric pressure plasma (CAP) on selected bacteria Escherichia coli and Staphylococcus epidermidis. A non-thermal microwave plasma torch was used. The plasma torch was connected to the software in the computer, which allowed its movement over the treated area. The used power fluctuated between 12–13 W and argon (gas purity 4.6) was chosen as the working gas with a constant flow rate of 5 l/min Inhibition efficacy was observed depending on the type of the selected treatment. The chosen treatment parameters included the effect of speed, direction, and treatment time for both studied bacteria. The aim was to achieve the highest decontamination of the treated area and to determine which of these parameters appeared to be the most significant. No obvious difference (between the treatment directions) was found in the overall decontamination of the treated area for studied bacteria Escherichia coli. The negative effect of speed was only observed for the fastest speed used in the case of gram-positive Staphylococcus epidermidis. The most significant parameter was found to be the treatment time, where a significant decrease in colony growth was observed with increasing treatment time. Furthermore, a repeated treatment was done, where the inoculum was prepared from the already treated bacteria. By this set of experiments, possible development of microbial resistance against the plasma treatment was tested. The results showed that there was no significant increase in the number of colonies even after the repeated treatment. It was also observed that the gram-positive bacteria Staphylococcus epidermidis showed lower decontamination effect evaluated via the number of colonies than the gram-negative bacteria Escherichia coli for all treatment types studied.
Study of plasma activated water effects on decomposition rate of organic matter using the “tea bag index” method
Bednařík, Tomáš ; Kalina, Michal (referee) ; Kozáková, Zdenka (advisor)
This bachelor thesis deals with the effect of plasma-activated water on the decomposition rate of organic matter using the tea bag index method. The first part of the theory of the bachelor thesis deals with plasma and plasma activated water. The second part deals with the tea bag index method and the analytical methods used in this thesis. In the experimental part, the aim of the thesis was to prepare plasma activated water using dielectric barrier discharge (DBD) and pin-hole discharge. Furthermore, to carry out the physicochemical characterization of plasma activated water, i.e., to determine the concentration of H2O2-, NO3-, NO2-, to measure its conductivity and pH, to determine the soil pH by two methods. The first method was determined using distilled water and the second using 0.2 M KCl. The last objective was to determine the rate of decomposition of organic matter using tea bag index and to assess the effect of plasma activated water on the physicochemical properties of soil. The results obtained indicate a positive effect on soil microorganisms and properties of plasma activated water. The next step in the investigation was to prepare a container experiment, produce and characterize plasma activated water for watering model plants, in this case lettuce.
Laser induced breakdown spectroscopy as a technique for elemental analysis of soft biological tissues
Fedra, Vojtěch ; Holub, Daniel (referee) ; Kozáková, Zdenka (advisor)
This bachelor's thesis deals with the optimization of selected measurement parameters for soft tissue analysis using the laser-induced breakdown spectroscopy (LIBS) method. The SNR values (signal-to-noise ratio for spectral ion line Ca II 393,37 nm) were investigated by the LIBS technique for a combination of settings. For the analyses, a laser with a wavelength of 266 nm and a laser with a wavelength of 1064 nm, different values of laser pulse energy, gate delay and for different atmosphere in the ablation chamber (without and with argon purge) were selected. The best results were obtained by using a 1064 nm laser and with argon purge, which led to a significant improvement in SNR. The results of the work are useful for further analysis of soft tissues using the LIBS method.
Influence of plasma activated water on seed germination and quality of corn
Kovařík, Martin ; Zlámalová Gargošová, Helena (referee) ; Kozáková, Zdenka (advisor)
The bachelor's thesis deals with the effect of plasma-activated water on corn germination. After water comes into contact with plasma, the water changes its chemical composition and thus, it acquires new properties that can be used in agriculture. The theoretical part is divided into two basic parts. At the beginning of the first part, plasma is briefly characterized, and then this part deals with plasma-activated water, its formation, physical and chemical properties, and at the end of this part, its use. The second part of the theoretical part is devoted to the germination of plants, external influences affecting germination and statistical evaluation of germination. At the end of the theoretical part, this thesis deals with the ecotoxicity of plants. The content of the experimental part was the preparation of PAW, its subsequent application to corn seeds and the study of its effect on germination and plant quality. PAW was created from distilled or tap water using three different plasma systems and the effect of each PAW on the seeds was compared with that of each control sample. The obtained results indicate a positive effect of PAW on seed germination, but the final hypothesis would require more extensive experiments in different environments, especially in soil.
Influence of plasma treated water on the plant growth and vitality
Vozár, Tomáš ; Zahoranová, Anna (referee) ; Kozáková, Zdenka (advisor)
This diploma thesis deals with the effect of plasma activated water on plant growth and vitality. By interaction of plasma with water, water acquires new unique properties that can be used in agriculture. The theoretical part deals with the basic properties of plasma, possibilities of preparation of plasma activated water in laboratory conditions, its physico-chemical characterization, and possibilities of its use in agriculture. In the next part, plant photosynthesis is discussed in connection with chlorophyll fluorescence, which measures the activity of photosystem II. Activity is an indicator of plant vitality, under environmental changes. At the end of the theoretical part, there are listed further possibilities for the analysis of plant material and food, such as elemental analysis, sensory analysis, and determination of dry matter content. Within the experimental part, plasma activated water (PAW) was prepared using plasma nozzle with introduced gas mixture that was immersed in the treated liquid. Further, plasma activated water was characterized and applied to radish plants. The effect of PAW on the plant growth and vitality was observed. The effect on the growth was observed through determination of fresh weight and dry matter content, the effect on vitality was assessed through chlorophyll fluorescence and the NDVI index. In the end, the effect on the content of stored elements C, H, O, and N in plants was determined and a sensory analysis was performed. The results show positive effects of plasma activated water on the plant growth and its sensory parameters such as appearance, taste, or spiciness. The results further show that PAW does not adversely affect plant vitality. This experiment should be continued by further indoor replication of the experiment to confirm obtained results and then, by moving the experiment to exterior in a form of field experiments.
Influence of plasma and plasma activated water on fungi Aspergillus niger
Žitný, Michal ; Čechová, Ludmila (referee) ; Kozáková, Zdenka (advisor)
The thesis deals with the issue of decontamination of Aspergillus niger mold using plasma, plasma-activated water and their combination. The theoretical part concerns the effects on the general properties of plasma, its generation, effects on microorganisms known so far and its use in industry with a special focus on medicine. It also focuses on the generation and characterization of plasma-activated water, its effects on bacteria, yeasts and fungi and its use. It also deals with the description of fungi, their occurrence and their sterilization. Part of the theory was aimed directly at the fungus Aspergillus niger. Its cultivation and its industrial uses, such as its use for the cultivation of citric acid, were described here. The experimental part deals with the characterization of plasma-activated water generated using a torch jet. The influence of the supplied power on the formation of particles in plasma-activated water was monitored. The decontamination effect of the plasma, generated by the torch jet, alone and in combination with plasma-activated water generated by alternating and direct current is monitored. The characterization of plasma activated water was performed with 20 ml of distilled water at a carrier gas rate of 2 l/min and a power of a microwave source of 9 and 12 W. The decontamination effect of plasma and its combination with plasma-activated water was observed by inoculating 100 l of a ten-fold and a hundred-fold diluted treated mold culture on Petri dishes with malt agar. The evaluation of the effect was carried out by counting the grown fungal colonies and subsequent comparison with control samples. All measured and obtained data were processed in the results. Plasma activated water generated by the torch jet has been found to contain higher concentrations of nitrogenous substances and lower concentrations of hydrogen peroxide, with the generated nitrate concentrations being higher at lower output than at higher output. DC-generated plasma activated water containing low concentrations of nitrogenous species and a very high concentration of hydrogen peroxide compared to PAW generated by a torch jet. Furthermore, plasma-activated water generated using a high frequency source contains minimal concentrations of nitrogenous substances and slightly elevated concentration of hydrogen peroxide in regard to torch jet PAW. The highest decontamination effect of all the methods used was the combination of plasma and plasma activated water, prepared by a plasma nozzle using direct voltage, when the plasma was applied first. On the contrary, the least effective method was the application of plasma and plasma activated water, generated by high frequency voltage. Limiting oxygen access had almost no effect on direct plasma treatment, but other methods were significantly affected by it. The greatest difference in decontamination effect was observed for the combination of plasma and plasma activated water, generated by high frequency current, where the difference was up to 30 %, but all methods had a significant decontamination effect compared to the control.
Study of chemical processes initiated by electrical discharge in liquids
Možíšová, Aneta ; Zlámalová Gargošová, Helena (referee) ; Kozáková, Zdenka (advisor)
This Bachelor´s thesis in the first part describes the process of ignition of the plasma discharge in water solutions, the generation of the particles that are generated during the discharge and their subsequent analysis by appropriate analytical methods. The second part focuses on specific cases of the use of the plasma discharge in the environment of selected electrolyte, phosphates were selected for individual experiments and for the comparison of sodium chloride. Phosphates were chosen mainly because of their stable pH as a possible benefit in discharge. The aim is to obtain the most ideal environment for the ignition of the plasma discharge and to optimize the method, which could subsequently be used for medical purposes, especially when sterilizing tools
Study of volatile hydrocarbon decomposition in non-thermal plasma of gliding arc at atmospheric pressure
Töröková, Lucie ; Rašková, Zuzana (referee) ; Kozáková, Zdenka (advisor)
Diploma thesis deals with gliding arc discharge in non-equilibrium plasma, its properties and usage for dissociation of volatile organic compounds. Plasma techniques create a perspective alternative to classical methods such as adsorption, biofilters, thermal processes, freezing and condensation. The method used for analysis of dissociation products is described in the theoretical part as well. Method is gas chromatography and it is combined with mass spectroscopy. The experimental part contains the overall description of GlidArc reactor where volatile organic compounds were dissociated. The volatile organic compound is brought into the reactor from the reservoir by carrier gas (nitrogen); synthetic air was used as working gas. The reactor is connected to the device for sampling. This device has several openings for sampling by SPME fibre method, sorption tubes method and a special opening for probe entry from the device Testo 350 M/XL, which enables instant analysis of low-molecular compounds. GC-MS was used for determination of high-molecular products of dissociation. Products sorbed on SPME fibres were analysed directly, compounds sorbed by active carbon were extracted by carbon disulphide. Samples obtained using SPME fibres were analysed. The major products of the dissociaton were found due to this analysis, those major products are in the case of hexane: pentanal, 4 methyl-3-pentanal, 2-butoxy-ethanol, pentane a 2-hexene. Major products detected when dissociating cyclohexane were: l,3-dimethyl-butane, propanal, cyklohexanone, 5-hexenal a 2-pentyn-1-ol. Major products of xylene dissociation were methyl-benzene, benzaldehyde, 4-methyl-benzaldehyde, 1-nitroethyl-benzene a benzenmethanol. After analysis obtained using sorption tubes showed that mainly the dissociated compound was sorbed, but the products of the dissociation were presented in too low concentration for an adequate analysis. For that reason the sorption tubes were used only for quantitative determination of the compounds depending on the power supply. The dependence of the dissociation of the compounds on the power supply was observed using SPME fibres which were used for quantitative determination. The Results obtained by both obtained techniques were almost in accordance. Speaking of low-molecular compounds, dissociation of all compounds gave the same products, i.e. carbon dioxide, hydrogen, nitrogen oxide, nitrogen dioxide and water. The results show that the dissociation of VOC gives - besides many potentially dangerous dissociation products - significant amounts of nitrogen oxides which is harmful to the environment. Hence it is necessary to be concerned with problems studied in the future mainly with respect to limitation of NOx generation. It will be possible to optimalize the conditions of the VOC dissociation on the basis of future kinetic analysis.
Study of electrolyte influence on diaphragm discharge stability and efficiency
Němcová, Lucie ; Krčma, František (referee) ; Kozáková, Zdenka (advisor)
This thesis is focused on so-called diaphragm discharge, which is one kind of electric discharges in liquid, which belongs among so-called AOP´s techniques, still more used for water cleaning in the present. One of effectiveness and stability indicators of diaphragm discharge is generation of hydrogen peroxide. In theoretical part, detail principle description of electric discharge in liquid is situated. Further, properties of electrolyte are introduced and general spectrophotometric method of obtained sample determination is described. In experimental part, a full procedure of experiment is introduced. Next part containing results and discussions introduces particular results of individual measurements and their reasons. Final chapter is the end, which forms total summary and evaluation of all results. By the application of all chosen electrolytes in solution at diaphragm discharge formation of hydrogen peroxide has appeared. Inorganic and organic electrolytes were used. As inorganic electrolytes following salts were selected – solutions of halogenides, next sodium nitrate as a representative of nitrates, potassium dihydrogenphosphate as a representative of phosphates, etc. Representative of organic electrolytes was citric acid. The value of initial conductivity of electrolytes had the main influence on hydrogen peroxide formation. Electrolytes potassium dihydrogenphosphate and sodium sulphate the great influence on effectiveness and stability of the diaphragm discharge. Their rate constants reached maximum value by the application of solution with initial conductivity of approximately 400 mikrosiemens, particularly 0.0492 mmol/l.min and 0.048 mmol/l.min. On the contrary, low values of rate constant were achieved in electrolyte ammonium chloride at around the same initial conductivity – 0.0269 mmol/l.min. During experiments stainless steel and platinum electrodes were used. It was found that kind of electrode material hadn’t influence on generation of hydrogen peroxide. Hydrogen peroxide was formed only in the cathode space.
Study on the influence of plasma activated water on seed germination
Vozár, Tomáš ; Zlámalová Gargošová, Helena (referee) ; Kozáková, Zdenka (advisor)
This bachelor thesis deals with study on the influence of plasma activated water on wheat seed germination. After interaction with the plasma, the water changes its composition and obtain new properties that are useful in agriculture. The theoretical part is divided into two parts. The first part of the theory is dealing with basic knowledge about plasma, its properties, and possibilities of plasma generation in laboratory conditions. In the second part, the work deals with plasma activated water – PAW. The preparation of plasma activated water is described in details as well as its physical-chemical properties and composition with respect to the PAW possible applications. The aim of the experimental part of this work was to prepare plasma activated water in three different plasma systems and apply it on wheat seeds. These three ways of activation used direct and indirect interaction of plasma with water surface. After the seeds were germinated, the influence of plasma activated water on seed germination and quality of crops was observed and compared to control samples. The influence of different ways of water activation was also evaluated. Results show positive effects of plasma activated water on the seed germination and it also increased the quality of crops. Next steps in this research should be the transfer of this experiment from the laboratory scale on the Petri dish to the pot experiments in soil.

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