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Diagnostics of active particles generated by the interaction of plasma microwave discharge with liquids
Kovaříková, Kateřina ; Töröková, Lucie (referee) ; Kozáková, Zdenka (advisor)
The first part of this Bachelor’s thesis describes problems of electric discharges in gas and on a surface of water solutions. It focuses on the generation of the active particles that are generated during the discharge and their subsequent analysis by appropriate analytical methods. The second part focuses on identification of the active particles that are generated during the microwave discharge in gas phase and during the interaction with water solution surface. The aim is to determine the influence of experimental conditions on the information of the active particles, specifically the nitrates and nitrite ions.
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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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Characterization and application of microwave plasma on wound healing
Smejkalová, Kateřina ; Skoumalová, Petra (referee) ; Krčma, František (advisor)
The aim of the Master thesis is the investigation of the influence of microwave discharge for skin wound healing. Microwave discharge used for this work was argon microwave plasma generated by the surface wave and direct vortex torch. The theoretical part is focused on basic information about plasma and processes that occur in plasma discharge under specific conditions. Plasma generates various active particles such as hydroxyl radicals, nitric oxide radicals, excited nitrogen molecules, atomic nitrogen, argon and oxygen. All of these particles together with plasma generated photons are usable in biomedical applications and summary of them is shown in the theoretical part. The experimental part is focused on the comparison of torch discharge and microwave plasma generated surface wave in skin wound healing. The model wounds on laboratory mousses were treated by plasma and wound healing was examined during 3 weeks after the plasma treatment. Both plasma systems showed healing acceleration. Application of torch discharge was proved to be the most effective method in the healing of skin defects. Additionally, determination of active particles was taken by optical emission spectroscopy. Based on these measurements, plasma parameters were determined: electron temparutare, rotational and vibrational temperatures. To determine role of different plasma active species, the treatment of indigo coloured artificial skin model was treated under various conditions by both plasma systems. Results show that the direct interaction between plasma particles is the main effect, role of radiation, only, is more or less negligible. Finally, the plasma vortex system was visualized using fast camera at selected powers and gas flows.
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Characterization of microwave plasma jet generated in argon-oxygen mixtures
Smejkalová, Kateřina ; Mazánková, Věra (referee) ; Krčma, František (advisor)
The optical diagnostics of microwave plasma torch operating at the frequency of 2,45 GHz is a subject of this bachelor thesis. Microwave plasma is generated using the surfatron resonator in argon with oxygen admixture (up to 1,7 %) at the constant argon flow of 3 Slm. The theoretical part gives the basic information about plasma and processes running under plasma conditions. Various active particles such as hydroxyl radicals, nitric oxides, excited nitrogen molecules, nitrogen, argon and oxygen atoms are generated in the discharge. All these particles together with the plasma generated photons can be used in biomedical applications that are briefly reviewed in the theoretical part, too. The visual observation of oxygen admixture on the discharge and the optical emission spectroscopy based determination of the active particles presence along the discharge and post-discharge axis is the subject of experimental part. Based on it, the selected plasma parameters like electron, rotational and vibrational temperatures were calculated.
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Characterization of microwave plasma jet generated in argon-nitrogen mixtures
Truchlá, Darina ; Mazánková, Věra (referee) ; Krčma, František (advisor)
This thesis is concerned with influence of nitrogen admixture to non-thermal microwave plasma jet generated in argon flow at atmospheric pressure. Non-thermal plasma can be used in more biomedical applications such cancer treatment, blood coagulation, sterilization etc. It is necessary to know the changes of plasma composition and its parameters in dependence nitrogen concentration to avoid potentional damages of the treated tissue. Plasma jet was characterized by optical emission spectroscopy along its axis. Electron, vibrational and rotational temperatures were calculated from intensities of the selected spectral lines and bands emitted by particles generated in plasma. The results show increase of the nitric oxide concentration followed by the increase UVC radiation. Temperature of the neutral gas increase too, but not so much and thus jet with nitrogen addition can be still used for the treatment of thermosensitive materials such as human tissue. Study of the sterilization effect of microwave plasma generated in argon-nitrogen mixtures is still under progress. Some of the results obtained during this thesis were included in the paper submitted into Journal of Physics D: Applied Physics.
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Special technical solutions in vacuum technology
SZABÓ, Robin
This thesis is focussed on the realisation of various technical solutions for microwave plasma apparatus. The theoretical part focuses on vacuum and general terms that are related. Attention was paid for example to definition of pressure, to pressure and central free track, units of measurement of pressure and their conversions. This part includes the classification of vacuum according to pressure. The next section of the dissertation is concerned with achieving vacuum including a description of rotary oil and turbo molecular pump. Part of the thesis includesa description of plasma microwave apparatus CX22 which was used during realisation of this dissertation. There is also a description of vacuum chamber, gas pump system, system of gas lead, microwave source, evaporator of liquid precursor and mixing apparatus. In the practical section a measurement of physical and technological quantity included. This part covers the inflow of apparatus measurement and temperatures of substrate during plasma process. In the next part there is a description of specific technical solutions suggested by the dissertation author. Amongst suggested technical solutions in this paper there is vacuum isolator, heating system of evaporator pipe, box of an evaporator of liquid precursor, ''gas ring'' and tablet equipment. Vacuum isolator was designed by 3D simulation and serves as a connection to detection technology. Heating of pipes of an evaporator were constructed to improve quality of the plasma process. The box of an evaporator was suggested for maintaining fresh air in a lab. A Gas ring was also designed by 3D simulation and serves as a specially adjusted pipe for bringing vapour of precursor near the substrate. The tablet equipment was constructed for unified preparation of compressed powder cellulosic tablets. Also from the available vacuum pumps, multilevel pumping was constructed that helped achievement of reduced lowest pressure.
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Plasma modification of materials for medical purposes
MATĚJÍČEK, Jan
This diploma thesis deals with the ongoing research under the auspices of the Department of Applied Physics and Technics Faculty of Education, University of South Bohemia in České Budějovice, in which the author of the work was actively participated. The thesis is divided into theoretical and experimental part. The theoretical part contains information from natural polymers, especially cellulose, plasma technology and infrared spectrometry. The subject of the experimental part of the thesis is research that deals with the functionalization of cellulose using a microwave plasma discharge on the apparatus CX-22. In the present research was also conducted to process optimization of functionalization with the liquid precursor hexamethyldisiloxane (HMDSO).
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Nanocrystalline diamond films deposition by PECVD in ASTEX type microwave reactor
Jašek, O. ; Karásková, M. ; Buršíková, V. ; Zajíčková, L. ; Franta, D. ; Frgala, Z. ; Matějková, Jiřina ; Rek, Antonín ; Klapetek, P. ; Buršík, Jiří
Nanocrystalline diamond film was deposited by microwave CVD in the ASTeX type reactor on a mirror polished (111) oriented n-doped silicon substrate. The deposition mixture consisted of 9 pct of methane in hydrogen. The applied microwave power (2.45 GHz)and pressure were 850 W and 7.5 kPa, respectively. The substrate temperature was 1 090 K. The diamond nucleation process was enhanced by rf induced dc selfbias of -125 V. The film exhibited very low roughness (rms of heights 9.1 nm). Its hardness and elastic modules were 70 and 375 GPa, respectively. The optical constants were determined by combination of spectroscopic ellipsometry and reflectometry employing the Rayleigh-Rice theory for the roughness and the dispersion model of optical constants based on the parameterization of densities of states. The deposition rate was 57 nm/min including the 5 min nucleation step.
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