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Atomization of hydride forming elements in dielectric barrier plasma discharges
Baranová, Barbora
The aim of this diploma thesis was to optimize the atomization conditions of two hydride forming elements - bismuth and tellurium in dielectric barrier discharge (DBD) plasma atomizers using atomic absorption spectrometry (AAS) as a detector. Two types of electrode constructions of planar DBD atomizers were studied: glued and sputtered electrodes while two construction of high voltage power supply sources were investigated employing either a sinusoidal or square wave modulation of high voltage function. The effect of the gas phase dryer included in the apparatus upstream the atomizer was also investigated. A nafion membrane tube dryer was identified as the most effective one. Its efficiency was verified using optical emission spectrometry. With the nafion tube included in the apparatus, two main parameters of DBD atomizers were optimized: the voltage of the power supply source and argon flow rate, which served as a discharge gas. Using optimal conditions, analytical characteristics were determined for all atomizers used and these were subsequently compared with those achieved in an externally heated quartz (multi)atomizer (MM)QTA. In the case of bismuth, the optimal argon flow rate was determined to be 75 cm3 min-1 for all atomizers. The optimal value for the power supply source with sinusoidal...
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Development of cosmetics emulsions with hemp extract
Baranová, Barbora ; Hudečková, Helena (referee) ; Márová, Ivana (advisor)
The hemp plant contains many biologically significant substances that are used in the food, pharmaceutical and cosmetic industries. Hemp extracts and oils are increasingly used in the cosmetics industry due to their antioxidant and antimicrobial activity. This bachelor's thesis deals with the characterization of hemp extracts and their use in the creation formulation of a moisturizing skin cream, the stability and assessment of the effects of this cream. In the theoretical part, individual hemp fractions, their composition and use in the cosmetics industry were discussed. As part of the experimental, the content of phenolic substances, flavonoids, chlorophylls and antioxidants in hemp extracts obtained by extraction using ethanol and tetrafluoroethane was analyzed spectrophotometrically. The content of cannabinoids was assessed by HPLC and TLC methods. The best characteristics were demonstrated by the ethanolic extracts of the Santhica and Fibror varieties, therefore they were used in the creation of a skin emulsion and its stability was tested by centrifugal and stress test. The skin cream was created with purely natural substances that are safe, environmentally friendly and effective. The resulting final product has demonstrated stability for approximately eight months and has been tested by volunteers. Their feedback confirmed the product's potential, with 70% reporting more hydrated and soothed skin. The development of a natural facial moisturizer with hemp extract provides a safer and more effective alternative to synthetic cosmetics and addresses the growing demand for sustainable and eco-friendly skin care options.
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Atomization of hydride forming elements in dielectric barrier plasma discharges
Baranová, Barbora ; Kratzer, Jan (advisor) ; Hrdlička, Aleš (referee)
The aim of this diploma thesis was to optimize the atomization conditions of two hydride forming elements - bismuth and tellurium in dielectric barrier discharge (DBD) plasma atomizers using atomic absorption spectrometry (AAS) as a detector. Two types of electrode constructions of planar DBD atomizers were studied: glued and sputtered electrodes while two construction of high voltage power supply sources were investigated employing either a sinusoidal or square wave modulation of high voltage function. The effect of the gas phase dryer included in the apparatus upstream the atomizer was also investigated. A nafion membrane tube dryer was identified as the most effective one. Its efficiency was verified using optical emission spectrometry. With the nafion tube included in the apparatus, two main parameters of DBD atomizers were optimized: the voltage of the power supply source and argon flow rate, which served as a discharge gas. Using optimal conditions, analytical characteristics were determined for all atomizers used and these were subsequently compared with those achieved in an externally heated quartz (multi)atomizer (MM)QTA. In the case of bismuth, the optimal argon flow rate was determined to be 75 cm3 min-1 for all atomizers. The optimal value for the power supply source with sinusoidal...
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