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Surface cleaning of archaeological objects by plasma generated in water solutions
Tihonová, Jitka ; Grossmannová, Hana (referee) ; Krčma, František (advisor)
This bachelor thesis is focused on the plasma surface treatment of historical ceramics by low temperature electrical discharges in water solution. Four samples were chosen - two of the Lusatian Urnfields Culture and two of Anabaptist Faience. The treatment was done at minimum power of the power supply. Stainless steel electrode and a specially designed electrode system with wolfram wire in the quartz glass capillary were used for generation of discharge using an audio frequency power supply. Elemental analysis by scanning electron microscopy (SEM) was done before and after the treatment and values were compared with the elemental analysis of material’s core. Samples of the Lusatian Urnfields Culture were successfully treated without any surface damage. The first one of samples of Anabaptist Faience was damaged. The experiment was repeated on the glass to determine the cause. It was find out that damage was probably caused by thermal stress. The second one of Anabaptist Faience was already treated without damage. Next research will be focused on determining specific conditions of the power supply, modification of water solution and modification of sample’s surface for the most efficient ancient ceramics cleaning.
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Study of low-temperature plasma products using mass spectrometry and their relation to thin film chemistry
Maršálek, Blahoslav ; Bránecký, Martin (referee) ; Čech, Vladimír (advisor)
The aim of this thesis was to analyse and interpret the spectra of tetravinylsilane as a function of plasma discharge power in order to find a relationship between plasma products, layer deposition and thin film chemistry. Another objective was to carry out a literature search in the field of plasma-enhanced chemical vapour deposition (PECVD) and mass spectrometry. Low temperature organosilicate-based plasma technology enables the synthesis of specific materials with controlled chemical and physical properties. The targeted synthesis of surfaces with controlled properties is determined by the atomic and molecular processes in the plasma, which are responsible for building the chemical structure and the resulting material in the form of a thin film. In this work, mass spectrometry has been used to detect and quantify the particles produced in the PECVD process, which is one of the methods that allow the characterization and identification of plasma products. Analysis of the mass spectra revealed that the molecules responsible for the growth of the layer contain carbon and silicon. The deposition rate determined by in situ spectroscopic ellipsometry correlates quantitatively with the flux of carbon and silicon particles that are chemisorbed on the film surface. The ratio of carbon and silicon deposited on the surface also correlates strongly with the C/Si flux ratio of the power driven plasmas. The contribution of silicon-containing particles as building blocks to the film growth decreases with increasing power and accounts for 20% (2 W), 5% (10 W) and only 1% (75 W) of the total chemisorbed fraction. This ratio between bound silicon containing particles and carbon particles affects the elemental composition and chemical structure of the deposited layers. The relationships between plasmachemical processes and particle adhesion on the surface are quite complex. The adhesion of silicon particles first increases sharply to a maximum at 25 W and then gradually decreases, which is characteristic of the so-called precursor-deficient PECVD. Similarly, the concentration of vinyl groups incorporated into the deposited layer and the fraction of sp2 hybridization of carbon correlate with the particle fluxes of the corresponding plasma. This work has demonstrated that mass spectroscopy is a suitable method for the study of plasmachemical deposition from the gas phase (PECVD). PECVD technology is promising for the deposition of silicon-containing layers, which is technologically applicable in many directions of materials research.
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Use of plasma jet for wound healing
Dvořáková, Eva ; Márová, Ivana (referee) ; Skoumalová, Petra (advisor)
This diploma thesis was focused on the possibility of using a plasma nozzle to accelerate the wound healing process. The benefits of using low-temperature plasma in medicine or biomedical applications are known from many studies, and low-temperature plasma is already used to sterilize medical devices, materials or surgical instruments. Some studies also report a high potential of usinh plasma nozzle in the treatment of skin wounds. In the experimental part of this work, an in vitro wound healing test was performed using two different low-temperature plasma sources. Source No. 1 was a surface wave microwave discharge and source No. 2 was a torch microwave discharge. An in vitro scratch healing test was performed on a monolayer of HaCaT keratinocytes and testing was performed using various parameters. The influence of the plasma treatment time was monitored, as well as the influence of the plasma discharge power and also the influence of the argon working gas flow. Especially when using a torch microwave discharge, faster wound healing was recorded at most of the parameters used compared to the control. Thus, it can be said that this source appears to be potentially suitable for faster wound healing. Furthermore, in the work using the MTT cytotoxicity test, the viability of skin cells after their plasmination was also monitored using the same conditions as in the in vitro wound healing test. When performed in the standard MTT assay, none of the settings or sources used showed any cytotoxic effects on keratinocytes. LDH cytotoxicity tests were also performed concurrently to verify the accuracy of the MTT assays. The results of both tests agreed and the use of low-temperature plasma in skin treatment can be considered as safe. Overall, the results show that the plasma nozzle can find use in medicine in the healing of skin wounds and chronic defects as a potentially fast, inexpensive and effective method.
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Study of plasma interaction with bacteria for wound healing
Šrámková, Sarah ; Krčma, František (referee) ; Kozáková, Zdenka (advisor)
This thesis focuses on the study of the interaction of plasma with bacteria to enhance the promotion of wound healing. Firstly, the wound healing process is described, followed by low temperature plasma, its effect on bacterial cells and its use in biomedicine. The experimental part deals with the application of low-temperature plasma generated by microwave jet on selected microorganisms and the influence of experimental conditions on the antimicrobial effect of the plasma. One representative of the microorganisms occurring in the wounds was selected as representatives of Gram-positive bacteria and Gram-negative bacteria, namely Staphylococcus epidermidis and Escherichia coli. Using the results obtained, the antimicrobial effect of plasma generated by microwave jet in argon was confirmed. The degree of antimicrobial effect is related to the concentration of the microorganisms, the time of treatment and whether the bacteria are Gram-positive or Gram-negative.
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Application of electric discharge in liquids for surface cleaning of non-metallic archaeological objects
Tihonová, Jitka ; Radko,, Tiňo (referee) ; Krčma, František (advisor)
This diploma thesis is focused on the plasma surface treatment of historical glass from the 18th and 19th centuries by low temperature electrical discharges in solutions of sodium chloride and potassium carbonate and finding the most suitable settings of conditions for the surface cleaning. Stainless steel electrode and a specially designed electrode system with wolfram wire in the quartz glass capillary were used for the generation of discharge using an audio frequency power supply. Each line of samples was made from one piece of historical glass that was cut to smaller pieces. All cleaned samples were photographed before and after the cleaning so the possible changes of the cleaned area could be visually compared. Then the samples were analysed by LA-ICP-MS (line scanning of surface), where was analysed the cleaned area of samples, and values were compared to the analysis of the reference sample that was not cleaned. Examined isotopes of elements were selected on the basis of the supposed composition of glass, corrosion products, and soil at the place of discovery. Analyses were standardized by NIST 610. Acquired values were transferred to oxides. The most important oxides (Na2O, MgO, SiO2, P2O5 a K2O) were chosen for deciding the most effective cleaning settings. It was decided that the most effective setting for cleaning was the one where the biggest difference of values between sample and reference occurred. Four series of these solutions were compiled and one parameter was changed for each of them. Solutions and their conductivity, frequency of the power supply, and time of cleaning were chosen as changing values. Three samples of different times of cleaning were cleaned without interruption. The time of cleaning was split into intervals of 30 seconds of cleaning and 1 minute of non-action for another two samples of this series. In this way we were trying to find out if the following surface analysis will be influenced by the diffusion of the particles into the sample, or not. The frequency of power supply was recorded and its dissipated power was calculated for each measurement. Emission spectra of a series of different solution conductivity were measured before cleaning of samples. Measurement of OES was made with the ignition of discharge so the active species of plasma were shown in spectra. These species are probably participating in the cleaning process of glass. Emission spectra were also measured after cleaning to find out if values of active species were changed or unknown spectral lines appeared. These lines should be from dirt and corrosion products that were cleaned from the surface of the glass. It was found out that the most effective cleaning of sample 1 (series where the conductivity of the NaCl solution was changed) was done in a solution of conductivity 900 S/cm. The most effective cleaning of sample 4 and sample 7 (series where the conductivity of the K2CO3 solution was changed) was done in a solution of conductivity 600 S/cm. The most effective cleaning of sample 6 (series where the frequency was changed) was done at frequency = (15200 ± 30) Hz. The most effective cleaning of sample 5 (series of different cleaning times) lasted seven minutes without time delay. The future research it should be appropriate to try a combination of these most effective cleaning settings on the surface of more samples, so the finding of this thesis will be confirmed.
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Plasma chemical removal of bronze corrosion layers
Miková, Petra ; Slavíček, Pavel (referee) ; Tiňo, Jozef (referee) ; Krčma, František (advisor)
The thesis deal with applying low-pressure low-temperature plasma to corrosion products layers on bronze. Layers of corrosion products on samples were artificially prepared. As a result, they had the same composition and could be irreversibly destroyed during experiments, which would not be possible with real archeological artifacts. Bronze, copper and tin alloy, samples were cut with respect to the size of the plasma-chemical device. XRF was used to determine the bronze composition. Before being corroded by the active medium, each sample was washed with ethanol and dried with a hot air stream. Until now, the procedure was the same for all samples. During formation of corrosion products layers, two factors have to be taken into account: the time consumption and the corrosiveness of the active environment. By focusing on one or the other factor, several groups of samples with differently degraded surfaces were created. The fastest way was to place samples in a corrosion chamber where sodium chloride solution was applied at the elevated temperature. The samples were corroded within a few days there. Longer, but in terms of corrosion products layers compactness better way proved procedure where the samples were sealed in the desiccator. At the desiccator bottom the Petri dish with an inorganic acid was placed, in our case, with hydrochloric acid inside. This method corroded the samples within one month. The longest but the most closed to the real live method was the burial of samples into soil or compost. However, this method corroded the samples within two years. Final step after the samples were removed from any corrosive environment, were dried under low pressure and were placed in a barrier film made bag together with moisture and oxygen absorbers. So prepared samples with layers of corrosion products have been treated in a low-pressure low-temperature plasma. Treatment was carried out in the apparatus which is based on the reactor: cylinder of quartz glass having a diameter of 100 mm and a length of 900 mm. The reactor was supplied with a working gas or a mixture of working gases with a total flow rate of 50 sccm. In our case, one is pure hydrogen or a combination with argon. A rotary oil pump was used to provide vacuum. The reactor base pressure was 10 Pa before treatment, while during the treatment it was 150 Pa. High-frequency generator (13.54 MHz) was used for supply the system with energy through two copper electrodes located outside the reactor. According to the energy delivery method, the treatment was carried out in a continuous or pulse mode. The sample temperature was monitored during the experiment and were evaluated the emission spectra from OES. The sample temperature was one of the key factors. The measurement was first done with a thermocouple, later switched to a thermocouple with optical data transmission. A safe temperature was set and then the whole process was controlled through it. In addition, the effect of the energy delivery method, value of the delivered power, sample size, presence of incrusted layers and composition of working gas were studied. After application of plasma, samples were analyzed by SEM – EDX and XRD. After the evaluation of the acquired knowledge and experience, a real artifact - a bronze chisel from the site of Boskovice - was treated. This documentation lacked the artifact, so it could be used to verify the lessons learned about plasma chemical reduction.
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Use of plasma jet for biomedical application
Doubravová, Anna ; Márová, Ivana (referee) ; Skoumalová, Petra (advisor)
This master´s thesis is focused on the utilization of the sterilization effects of low temperature plasma towards the bacterial microorganisms that occur mainly on the human skin. The plasma sterilization process is fast efficient, non-toxic, environmentally friendly, cost-effective and safe for the operating staff as well as for the patient. Another advantage of using low temperature plasma is to support cell proliferation and wound healing. By combining these advantages, an effective method can be obtained, which would sterilize the wounds sparingly with regard to the surrounding healthy tissue and support the regeneration of the damaged tissue at the same time. In the experimental part, gram positive and gram negative bacteria were used to prove the sterilization effects with respect to different cell wall structure. Staphylococcus epidermidis and Propionibacterium acnes, which cause purulent skin inflammations, were used as gram-positive microorganisms. Serratia marcescens and Escherichia coli were selected from gram positive bacteria. These model organisms were inoculated at various concentrations on culture broths and treated by plasma at a distance of 1 mm from the agar surface. The microwave discharge was generated in argon at a power of 9 W, a gas flow rate of 5 l / min and water cooling to avoid thermal effects on the treated surface. Subsequently, model skin cells of HaCaT were exposed to low temperature plasma and tested for plasma cytotoxicity to demonstrate its healing effects. The obtained results make it possible to state that the sterilizing effects of low-temperature plasma in all tested gram-positive and gram-negative bacterial strains are verified in this work. Finally, tests were demonstrated using a suitable method of the treatment on human skin cells, where the safety and usefulness of the tested low-temperature plasma was demonstrated when applied to shorten the healing process.
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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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Study of low-temperature plasma products using mass spectrometry and their relation to thin film chemistry
Maršálek, Blahoslav ; Bránecký, Martin (referee) ; Čech, Vladimír (advisor)
The aim of this thesis was to analyse and interpret the spectra of tetravinylsilane as a function of plasma discharge power in order to find a relationship between plasma products, layer deposition and thin film chemistry. Another objective was to carry out a literature search in the field of plasma-enhanced chemical vapour deposition (PECVD) and mass spectrometry. Low temperature organosilicate-based plasma technology enables the synthesis of specific materials with controlled chemical and physical properties. The targeted synthesis of surfaces with controlled properties is determined by the atomic and molecular processes in the plasma, which are responsible for building the chemical structure and the resulting material in the form of a thin film. In this work, mass spectrometry has been used to detect and quantify the particles produced in the PECVD process, which is one of the methods that allow the characterization and identification of plasma products. Analysis of the mass spectra revealed that the molecules responsible for the growth of the layer contain carbon and silicon. The deposition rate determined by in situ spectroscopic ellipsometry correlates quantitatively with the flux of carbon and silicon particles that are chemisorbed on the film surface. The ratio of carbon and silicon deposited on the surface also correlates strongly with the C/Si flux ratio of the power driven plasmas. The contribution of silicon-containing particles as building blocks to the film growth decreases with increasing power and accounts for 20% (2 W), 5% (10 W) and only 1% (75 W) of the total chemisorbed fraction. This ratio between bound silicon containing particles and carbon particles affects the elemental composition and chemical structure of the deposited layers. The relationships between plasmachemical processes and particle adhesion on the surface are quite complex. The adhesion of silicon particles first increases sharply to a maximum at 25 W and then gradually decreases, which is characteristic of the so-called precursor-deficient PECVD. Similarly, the concentration of vinyl groups incorporated into the deposited layer and the fraction of sp2 hybridization of carbon correlate with the particle fluxes of the corresponding plasma. This work has demonstrated that mass spectroscopy is a suitable method for the study of plasmachemical deposition from the gas phase (PECVD). PECVD technology is promising for the deposition of silicon-containing layers, which is technologically applicable in many directions of materials research.
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Study of plasma interaction with bacteria for wound healing
Šrámková, Sarah ; Krčma, František (referee) ; Kozáková, Zdenka (advisor)
This thesis focuses on the study of the interaction of plasma with bacteria to enhance the promotion of wound healing. Firstly, the wound healing process is described, followed by low temperature plasma, its effect on bacterial cells and its use in biomedicine. The experimental part deals with the application of low-temperature plasma generated by microwave jet on selected microorganisms and the influence of experimental conditions on the antimicrobial effect of the plasma. One representative of the microorganisms occurring in the wounds was selected as representatives of Gram-positive bacteria and Gram-negative bacteria, namely Staphylococcus epidermidis and Escherichia coli. Using the results obtained, the antimicrobial effect of plasma generated by microwave jet in argon was confirmed. The degree of antimicrobial effect is related to the concentration of the microorganisms, the time of treatment and whether the bacteria are Gram-positive or Gram-negative.
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