Ústav fyzikální a spotřební chemie
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- ItemPlasma treated water as a tool for sustainable applications(Czech Technical University in Prague, 2024-05-29) Kozáková, Zdenka; Čechová, Ludmila; Šťastná, Kateřina; Šindelková, Kateřina; Korečková, Svatava; Krčma, FrantišekPlasma treated water was prepared by non-thermal plasma systems using plasma interaction above or inside liquid or in a remote bubbling regime. Plasma treated water prepared from distilled, tap or water solutions was characterised by physical properties (pH, conductivity) and colorimetric determination of stable chemical species (hydrogen peroxide, nitrites, and nitrates). Its quality was evaluated with respect to its possible utilization in sustainable agriculture and medicine applications.
- ItemAntimycotic effects of the plasma gun on the yeast Candida glabrata tested on various surfaces(WILEY-V C H VERLAG GMBH, 2024-07-04) Trebulová, Kristína; Orel, Inna; Pouvesle, Jean Michel; Robert, Eric; Rouillard, Amaury; Stancampiano, Augusto; Hrudka, Jan; Menčík, Přemysl; Kozáková, Zdenka; Měšťánková, Zuzana; Kužmová, Darina; Paličková, Ivana; Čížek, Alois; Krčma, FrantišekThis work focuses on the antimycotic effects of the plasma gun as a potential tool for the treatment of superficial infections. Candida glabrata was chosen as a model microorganism. The preliminary tests have been done on the agar plates to establish the basic plasma parameters. To render this research more appropriate to the real application, more complex inoculation substrates, pork skin and 3D-printed models of the dog ear canal have been used. The results of this work confirm the high efficiency of cold plasma in the inhibition of yeasts on different surfaces and will lead to further experiments.
- ItemBiochar Texture – A Parameter Influencing Physicochemical Properties, Morphology, and Agronomical Potential(MDPI, 2022-07-28) Kalina, Michal; Bačovská, Šárka; Hajzler, Jan; Kubíková, Leona; Trudičová, Monika; Smilek, Jiří; Enev, VojtěchBiochar represents a stable form of carbon-rich organic material produced by the pyrolysis of various biomass residues. It has the potential to stabilize organic carbon in the soil and improve soil fertility, water retention, and enhance plant growth. Despite its potential, there is limited information on the mutual relation of biochar texture with its physicochemical characteristics, morphology, and the content of organic matter. For these reasons, we studied three biochar samples with potential use in agriculture as soil supplements (NovoCarbo, Sonnenerde, Bi-ouhel.cz). Our experimental approach performed on the individual sieved fraction of studied biochars (<0.5; 0.5–2.0; 2.0–4.0 and >4.0 mm) confirmed the importance of a selection of optimal source biomass material as the content of lignin, cellulose, and hemicellulose, together with the conditions of pyrolysis (temperature of pyrolysis), play a crucial role in the managing of the properties of produced biochar. Agronomically more stable biochars containing a higher con-tent of organic matter and organic carbon, with alkaline pH response and well-developed aro-matic porous structure, could be produced from lignin-based biomass residues at higher pyroly-sis temperatures, which is an important finding taking into account the possible utilization of biochar in soils as a soil conditioner.
- ItemThermodynamic Analysis of the Landolt-Type Autocatalytic System(MDPI, 2021-10-28) Pekař, MiloslavA recent work demonstrated on the example of the Landolt-type reaction system how the simplest autocatalytic loop is described by the kinetic mass action law and proper parametrization of direct and autocatalytic pathways. Using a methodology of non-equilibrium thermodynamics the thermodynamic consistency of that kinetic model is analyzed and the mass action description generalized including an alternative description by the empirical rate equation. Relationships between independent and dependent reactions and their rates are given. The mathematical modeling shows that following the time evolution of reaction rates provides additional insight into autocatalytic behavior. A brief note on thermodynamic driving forces and coupling with diffusion is added. In summary, this work extends and generalizes the kinetic description of the Landolt-type system placing it within the framework of non-equilibrium thermodynamics and demonstrating its thermodynamic consistency.
- ItemPhysico-Chemical Properties of Lithium Silicates Related to Their Utilization for Concrete Densifiers(MDPI, 2023-03-08) Kalina, Lukáš; Bílek, Vlastimil; Sedlačík, Martin; Cába, Vladislav; Smilek, Jiří; Švec, Jiří; Bartoníčková, Eva; Rovnaník, Pavel; Fládr, JosefProtection of concrete against aggressive influences from the surrounding environment becomes an important step to increase its durability. Today, alkali silicate solutions are advantageously used as pore-blocking treatments that increase the hardness and impermeability of the concrete’s surface layer. Among these chemical substances, known as concrete densifiers, lithium silicate solutions are growing in popularity. In the present study, the chemical composition of the lithium silicate densifiers is put into context with the properties of the newly created insoluble inorganic gel responsible for the micro-filling effect. Fourier-transform infrared spectroscopy was used as a key method to describe the structure of the formed gel. In this context, the gelation process was studied through the evolution of viscoelastic properties over time using oscillatory measurements. It was found that the gelation process is fundamentally controlled by the molar ratio of SiO2 and Li2O in the densifier. The low SiO2 to Li2O ratio promotes the gelling process, resulting in a rapidly formed gel structure that affects macro characteristics, such as water permeability, directly related to the durability of treated concretes.