National Repository of Grey Literature 46 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Influence of different forms of titanium dioxide nanoparticles on soil organic matter properties
Miklasová, Marta ; Řezáčová, Veronika (referee) ; Kučerík, Jiří (advisor)
Nanoparticles present potential risk for environmental compartments including soil. Previous works have been focused on negative effects of nanoparticles on soil biota, however studies about the influence of nanoparticles on soil properties are still limited. This thesis investigates an impact of 20 nm titanium dioxide nanoparticles on selected water properties in soil organic matter exposed to air with various relative humidity. Indeed, at 43, 70 and 95 % dominate different water types, i.e. water adsorbed on soil organic matter, water in water molecular bridges and phase water, respectively. Differential scanning calorimetry (DSC) was used in the study. An important finding is that nanoparticles reduce the stability of water molecular bridges under 70% relative air humidity and generally reduce evaporation enthalpy of water, which represents the ability of the soil to retain water. In the next part the influence of nanoparticles on total water in soil was observed. Under low relative humidity, rutile and anatase affected soil in different ways due to their various hydrophilicity. Under higher relative humidity this effect disappeared. In the last part, ice melting and water evaporation enthalpies of nanoparticle solutions were measured to confirm the presumed effect of nanoparticles on water. The ice melting enthalpy of the solutions was higher relatively to pure water, while the evaporation enthalpy showed a reverse trend (decrease). This confirmed the effects of nanoparticles both for pure water and soil water.
The study of behavior of platinum nanoparticles in environmental compartments
Berka, Michal ; Řezáčová, Veronika (referee) ; Komendová, Renata (advisor)
Platinum nanoparticles pose a risk to environmental compartments. The aim of this diploma thesis is to conduct research on the influence of platinum nanoparticles in a wide range of concentrations on soil properties at different humidities. Specifically, it is about influencing the stability of water molecular bridges, the content of aliphatic crystallites, the retention capacity of water in the soil and the strength of water binding. Furthermore, the amount of nanoparticles sorbed on the soil was also measured. These indicators give us more information about the influence of platinum nanoparticles on evapotranspiration and soil deterioration. Methods of thermal analysis (differential scanning calorimetry) and optical methods (atomic absorption spectrometry) were used for these researches. The theoretical part of the work is devoted to a comprehensive introduction to platinum and its nanoparticles, as well as aqueous molecular bridges. It has been found that 200 nm platinum nanoparticles affect the strength of aqueous molecular bridges, have no effect on aliphatic crystallite content, have minimal effect on soil water retention, and that the water bond strength decreases due to platinum nanoparticles at high relative humidity. With 200 nm platinum nanoparticles, complete adsorption to soil occurs over the entire concentration range. With 3 nm nanoparticles, the soil is supersaturated at higher concentrations and larger amounts are not adsorbed. The results show that the larger the size of the platinum nanoparticles, the lower the negative effect on evapotranspiration and soil function itself.
Zinc in food suplements
Sauchanka, Katsiaryna ; Suková, Petra (referee) ; Řezáčová, Veronika (advisor)
The aim of this bachelor thesis was to determine zinc in the dietary supplements by the voltammetric method. The general properties of zinc, its occurrence, toxicity and influence on human health are described in the first part. Next the methods, including a detailed description of the voltammetric analysis, are summarized. The experimental part is focused on the process of optimization of the conditions for zinc voltammetric analysis and the application of the optimised method on real samples.
Analysis of volatile organic compounds produced by monocytes during sepsis
Bártová, Adéla ; Řezáčová, Veronika (referee) ; Mravcová, Ludmila (advisor)
This thesis is focused on the possibility of analysis of volatile organic compounds produced by monocytes during sepsis. Method of comprehensive two-dimensional gas chromatography with mass spectrometric detection was chosen for this purpose. Content of the first part was the optimization of the method of two-dimensional gas chromatography for the determination of volatile organic compounds. In this part were gradually adjusted parameters of the gas chromatography method to achieve the maximum efficiency. Further were adjusted conditions of samples preparation. Content of the second part was the usage of already optimized method for the analysis of the samples set of monocytes. Samples were subjected to the action of different inhibitors of the immune system and stimulators simulating bacterial or yeast infection. Based on this analysis were identified some compounds, which are produced by monocytes under condition simulating the infection.
Use of derivatization methods in gas chromatography
Brédová, Boglárka ; Řezáčová, Veronika (referee) ; Mravcová, Ludmila (advisor)
This study is focused on verifying the possibility of derivatization in gas chromatography for the determination of fatty acids in oil samples and on the use of derivatization for the determination of organic substances in a sample of vine seed extract. The theoretical part deals with the characteristics of individual analytes. In the next section derivatization methods and transesterifications for fatty acid determination are described. The last chapter deals with the basic knowledge of gas chromatography and its instrumentation. The experimental part was divided into three chapters: analysis of fatty acids by transesterification, determination of mono- , di-, and triglycerides by derivatization and analysis of grape seed extracts. Three types of oils were analyzed in the experimental part: poppy, linseed and nut oil. The most common fatty acids in plant oils are palmitic, stearic, oleic, linoleic and linolenic acids. The optimization method was carried out using the derivatizing agent MSTFA. The determination of fatty acid methyl esters was measured on a gas chromatograph with a flame ionization detector. To confirm the presence of fatty acids, additional analysis was used on gas chromatograph with a mass spectrometer. Analysis of the grape extract was also performed on GC/MS. The method was most convenient using MSTFA, BSTFA and BSA+ TMCS derivatizing agents.
Analysis of biodegradable polymers in soils
Paluchová, Natálie ; Řezáčová, Veronika (referee) ; Kučerík, Jiří (advisor)
Currently, there is a growing interest in usage of biodegradable polymers, regardless of their possible risk of generation of residues. The methods that are used for determination of residues usually include pre-treatment and are expensive and time consuming. Therefore, this bachelor thesis focuses on the development and verification of analytical method that would identify and quantify of biodegradable polymer residues in soils to eliminate the problems arising from sample pre-treatment. Therefore, thermogravimetry, which appears to satisfy the above conditions, was used for the analysis. The area of polymer degradation in three types of soils during thermal oxidation and the effect of polymer on soil during the analysis was investigated. Poly(3 hydroxybutyrate) was chosen to be the representative biodegradable polymer and there were two approaches used to its detection and quatification. The methods were tested for 6 concentrations of poly(3–hydroxybutyrate) (0,1; 0,5; 1; 2; 3; 5 %). The first approach concentrated on the usage of polymer analysis in the presence of a blank (without contaminat), which was subtracted from the blank. Using this method, the temperature interval of polymer degradation and weigh loss changes in this interval were observed. The second method focused on a soil universal model, that allows the identification and quatification of samples when the blank is not present. The blank is simulated by 19 equations, that allow the identification of intervals, in which degradation of samples occurs and also it provides the possibility to determinate the type of the polymer. However, the principle component analysis indicated that the method is sensitive to the type of soil and therefore it needs adjustments. Samples were incubated for 4 months, to verify the sensitivity of the method, in case of partial or complete decomposition of samples by soil microorganisms,. Thereafter, the concentrations of poly(3-hydroxybutryrate) in soil determined by respirometry and thermogravimetry were compared. The results indicated that accelerated degradation caused by poly(3-hydroxybutrylate) or contamination of the sample with the surrounding atmosphere during respiration may have occurred. Residual poly(3–hydroxybutyrate) was thermogravimetrically verified and results were compared to respirometry. According to the results it can be observed that there was an interaction between the soil organic matter and biota or contamination of the sample with the surrounding atmosphere. The results revealed, that there is a possibility of determination of biodegradable polymers in soils by thermogravimetric analysis. There are good results using the blank method, but it is limited by the existence of a blank. The method that is using the soil universal model (without blank) has a great potential in the future, but adjustments still need to be done.
Determination of organic acids in wine
Michálková, Kateřina ; Mravcová, Ludmila (referee) ; Řezáčová, Veronika (advisor)
This bachelor thesis deals with determination of organic acids in wine by capillary zone isotachophoresis method. The theoretical part is devoted to the properties of wine, its composition, its benefit to human health and capillary zone isotachophoresis and its practical use. The practical part deals with determination of organic acids in wine by capillary zone isotachophoresis. Organic acids are determined in three phases of white and red wine production.
Determination of substances in phytopharmaceuticals
Ivanishchanka, Iryna ; Řezáčová, Veronika (referee) ; Vávrová, Milada (advisor)
In the bachelor thesis, herbal teas, the main components of which are St. John's Wort and Lemon balm, were analyzed. The physiological properties, the chemical composition and the influence on human health were monitored. Thesis deals method of isolation and identification of essentials oils from out of selected teas to calm the nervous system. For isolation of essentials oils there are used methods solvent extraction, solid phase microextraction (SPME) and steam distillation, for identification there is gas chromatography (GC/MS). Isolation methods for obtaining essential oils from plant matrices were assessed and the most appropriate isolation techniques was determined by solid phase microextraction (SPME)
Spectrophotometric determination of chlorophyll
Rábová, Petra ; Kerberová, Veronika (referee) ; Řezáčová, Veronika (advisor)
This bachelor thesis is focused on determination of chlorophyll in leaves by the method of extraction spectrophotometry. The theoretical part provides information about photosynthesis, stress factors or plant adaptation, photosynthetic pigments (especially chlorophyll-a) and application of spectrophotometry and other methods of chlorophyll determination. The experimental part is focused on the application of the ecotoxicological test and, above all, it is evaluation by two independent methods. Specifically, it was determination of biomass growth inhibition and newly spectrophotometrical determination of chlorophyll mass. The results correlate with each other, therefore, the determination of chlorophyll seems to be an appropriate extension of usual evaluation methods of ecological tests.
Study of contamination of river sediments with platinum metals
Novotný, Matěj ; Řezáčová, Veronika (referee) ; Komendová, Renata (advisor)
This work deals with the characteristics of platinum metals and problems related to their toxicity and mobility in the environment, especially in the aquatic environment. These metals are released into the environment due to the use of automotive catalysts. Their function is based on the catalytic properties of platinum metals. Because of the high temperatures, these metals can be oxidized in the catalyst and subsequently emitted together with the combustion products into the surrounding atmosphere. The aim of the thesis is to measure real samples of river sediments of the river Svratka on the territory of the city of Brno and to find the possibility of contamination of the aquatic environment with these metals.

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8 ŘEZÁČOVÁ, Veronika
1 Řezáčová, Vendula
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