National Repository of Grey Literature 251 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Development of electroanalytical methods for detection of cholesterol, 7-dehydrocholesterol and cholecalciferol
Benešová, Lenka ; Schwarzová, Karolina (advisor) ; Navrátil, Tomáš (referee) ; Šelešovská, Renáta (referee)
Steroidival substances are an integral part of the human organism, such as bile acids, steroid hormones, vitamins. The most important sterol in whole organism is cholesterol, which is cornerstone of the all cell membranes. It is involved in important processes in the body, but its storage in blood vessels in the formo f low-density lipoprotein (LDL) is crucial of reason serious health diseases as atherosclerosis, myocardial infarction and others. 7-dehydrocholesterol is a precursor of cholesterol and another sterol compound studied by me, cholekalciferol, also known as a vitamin D3. Deficiency of 7-dehydrocholesterol reductase is the main indicatior of the possible genesis of Smith-Lemli-Opitz syndrome. One of the goals of this thesis was developed a suitable electrochemical method to facilitate the diagnosis of this syndrome from plasma and amniotic fluid in the prenatal and postnatal phases of pregnancy. Within the framework of this thesis were developer electrochemical methods in a batch and flow arrangement for detection of the above-mentioned sterols, namely cholesterol, 7-dehydrocholesterol and cholekalciferol. It was wokered in the medium contain perchloric acid or its salt sodium perchlorate in acetonitrile as supporting electrolyte. It was worked in the wide range of working disc...
Mercury dynamics in soil systems: A comprehensive study on natural and anthropogenic sources using elemental and isotopic analysis
Domingues Vieira, Alda Maria ; Vaňková, Maria (advisor) ; Navrátil, Tomáš (referee) ; Doušová, Barbora (referee)
Human activities (in)directly affects the biogeochemical cycle of mercury (Hg) in the environment. However, many aspects of Hg behaviour remain poorly understood. In this thesis, three different case studies addressed two main themes: i) the influence of climate change on Hg re-emissions from fire-affected soils and ii) the fate and behaviour of Hg in soils contaminated by non-ferrous ore mining and smelting. The first study investigated total Hg concentrations in uncontaminated soil profiles and Hg pools in organic horizons to estimate the fire-induced Hg emissions from the soil during a wildfire in Portugal. Fire-undisturbed soil profiles displayed higher Hg concentrations (156 μg kg-1) in the organic horizons, decreasing with depth in the mineral horizons. The Hg pool in these organic horizons was estimated at 10.6 g ha- 1. We calculated the wildfire released up to 133 g of Hg from the forest floor within the 12.5 ha burned area, emphasising its dual role in Hg (im)mobilisation in a region increasingly affected by extreme fire-prone weather events. In the second study, Hg stable isotope ratios and solid phase speciation data were determined in soil profiles contaminated by historical Hg-Fe mining and smelting in Czechia (Jedová Hora). The total Hg soil concentration reached up to 17.8 mg kg-1....
Applications of Machine Learning in Predictive Maintenance of Industry 4.0
Navrátil, Tadeáš ; Richter, Miloslav (referee) ; Horák, Karel (advisor)
The thesis develops machine learning algorithms for use in the Industry 4.0 concept. The main focus is on predictive maintenance and visual inspection. In the theoretical part, the thesis focuses on a literature search of machine learning methods in the field of anomaly detection in time series and image data. The practical part deals with the reimplementation of the selected methods and their evaluation using the confusion matrix and metrics based on it
Elimination Voltammetry with Linear Scan: Advantages and Disadvantages
Navrátil, Tomáš ; Trnková, L. ; Hrdlička, Vojtěch ; Li, X.
Elimination voltammetry with linear scan (EVLS) represents an almost traditional\nmathematical method that helps to obtain additional and detailed information about the recorded\nelectrochemical signals and therefore, to better understand the analyzed systems. Although it\nhas been substantially developed and expanded during its existence of more than a quarter of a\ncentury and has found many areas of application, like any other mathematical and experimental\nmethod, it exhibits several advantages and disadvantages. In this contribution, we summarize\nits strengths, weaknesses, opportunities, as well as threats.\n
Determination of Selected Natural Psychoactive Substances in Organic Matrices at 3D Printed Electrodes
Choińska-Mlynarczyk, Marta ; Šestáková, Ivana ; Navrátil, Tomáš
Psilocybin and its derivative psilocin are popular psychoactive substances both as experimental\ntreatments in clinical trials and as illicit drugs. Their potential ability to influence the human\nbrain entails the need for a fast, inexpensive, selective, and sensitive method of their\ndetermination. The aim of our study was the development of new 3D-printed electrodes which\nfulfill these demands and are useful for medical, toxicological, and forensic purposes.\nSuccessful development allows determining in real matrices (human plasma and dried\nmushrooms) concentrations of the order of 1 μmol dm-3.\n
Analytical Derivatization for Identification of Electrochemical Oxidation Products of Fentanyls
Barták, P. ; Skopalová, J. ; Jerga, R. ; Štolbová, D. ; Navrátil, Tomáš ; Langmaier, Jan
Analytical derivatization and GC-MS analysis were employed for the identification of main\nproducts from the electrochemical oxidation of fentanyl derivatives. Chemical derivatization\nprovides proof of the chemical reactivity of functional groups in oxidation products and serves\nfor the chemical conversion of target compounds into the second series of derivatives to confirm\nthe identification of particular products. Using the direct GC-MS analysis of oxidation products,\nderivatization of aldehydes with cysteamine and derivatization of amides by acidic hydrolysis\nand subsequent reaction with ethylchloroformiate, phenylacetaldehyde, and Nphenylpropanamide\nwere unambigously identified as oxidation products from fentanyl,\nthiophen-2-ylacetaldehyde, and N-phenylpropanamide from sufentanil, and\nphenylacetaldehyde and 2-furanilid from furanylfentanyl.
Vliv vybraných podmínek prostředí na klíčení semen plevelů
Navrátil, Tomáš
The aim of this thesis was to find out the influence of temperature on germination seeds of Galium aparine. There were suggested labour experiments. In the first experiment seeds were exposed to various temperatures. In the second experiment was monitoring the influence on germination of seeds which were exposed to frost for a specific time. Best germination had seeds at 6 °C. In the second experiment the best germination had seeds that were exposed to frost for five days. Average total germination of all seed were 65.8%. Results have been written to the tables and processed to graphs. Evaluation of the work is adduced in discussion.
Carbon - based electrodes: From detection of biologically significant compounds to application in neurodegenerative diseases
Jarošová, Romana ; Zima, Jiří (advisor) ; Vyskočil, Vlastimil (referee) ; Navrátil, Tomáš (referee)
CARBON BASED ELECTRODES: FROM DETECTION OF BIOLOGICALLY SIGNIFICANT COMPOUNDS TO APPLICATION IN NEURODEGENERATIVE DISEASES By Romana Jarošová Carbon is a truly remarkable element that is essential to life on Earth, and its unique properties have made it an indispensable component in an astonishingly diverse array of applications. Whether serving as a fuel source or as a key component in electronic devices, carbon's ability to exist in different forms, each with their distinct physical and chemical properties, contributes to its widespread and continued use. Electrode production is one of the areas where carbon found its significant use. This thesis represents a unique combination of fundamental and applied electrochemistry using carbon-based electrodes. It explores a wide range of topics, from evaluating electrode microstructure as a critical factor affecting its electroanalytical behavior, to the use of carbon- based electrodes in Alzheimer's disease (AD) research. The first part of this Thesis focuses on the electrochemical performance of carbon-based electrodes with distinct microstructures. Specifically, this section discusses two novel electrode materials: boron-doped diamond and nitrogen-incorporated tetrahedral amorphous carbon. The microstructure of each electrode was investigated, and the...
Analytical approaches to study group interactions of azole pesticides with important biological active compounds
Kovač, Ishak ; Jaklová Dytrtová, Jana (advisor) ; Száková, Jiřina (referee) ; Navrátil, Tomáš (referee)
This dissertation presents a developed capillary electrophoresis method for analysing residues of triazole fungicides (TAF) from real samples ("Sweet cherry" tomato - Solanum lycopersicum L) and shows its potential application in environmental analysis. The developed method was validated in-house and characterised by a relatively short analysis time and low cost with sufficient LOD and LOQ. As an additional part of this dissertation, which rose from the tomato plants' treatment with TAF, we studied the impact of triazole fungicides on plant development and their impact on biologically active compounds. Determination of TAF residues from tomato peel carried out with capillary electrophoresis. Capillary electrophoresis is a versatile technique with minute amounts of sample required, with high efficiency in separating small molecules, such as selected TAF. The developed method, cyclodextrin-modified micellar electrokinetic chromatography, accomplished a baseline separation of the TAF mixture from tomato peel. The optimal conditions for separation were in the background electrolyte comprised of phosphoric acid and Tris (100 mM concentration, respectively), 20% v/v methanol, with apparent p[H+ ] 4.8. The constituents of the mixed micellar pseudo-stationary phase were ionic detergent sodium dodecyl...

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