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Utilization of biomass for micro cogeneration
Daňhel, Aleš ; Šejvl, Radovan (referee) ; Baxant, Petr (advisor)
This master’s thesis deals with utilization of biomass for micro cogeneration. The theoretical part of the master’s thesis defines main terms of the master’s thesis, which is biomass and cogeneration. The practical part of the master’s thesis is focused on the design and manufacturing of small micro cogeneration unit based on a small membrane steam engine. It means design of two steam generators to produce steam for the membrane steam engine. It will be also carried out design and production of membrane steam engine which is fitted with a small BLDC generator including electrical part for power output and measuring parameters. It will be made several measurements with the steam engine including measuring power output characteristic of the steam engine and measuring loading characteristics of the generator.
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Sodium cooled fast reactors
Daňhel, Aleš ; Katovský, Karel (referee) ; Foral, Štěpán (advisor)
This bachelor’s thesis deals with the sodium-cooled fast reactors. It comprehensively describes the problem of sodium-cooled fast reactors. Attention was paid to the basic specifications and parameters of these reactors. There was briefly described nuclear reactions which are under way in core of sodium-cooled fast reactors but also chemical reactions which are linked to function of liquid sodium as a coolant and heat transfer substance. Attention was also paid to the differences in the reactor core configuration and to the machine device specific for sodium-cooled fast reactors. Further on this bachelor’s thesis puts on the overview of sodium-cooled fast reactors that have worked, are still working or are under construction in each country all over the world. There was briefly described generation IV nuclear reactors, particularly its history and reasons that originate generation IV. Under generation IV was also described nuclear reactor SFR and highlighted differences compared to existing sodium-cooled fast reactors. In the practical part of this bachelor’s thesis is easily made a calculation of the heat transfer from the fuel rod to the cooling sodium and there is also mentioned course of the heat transfer coefficient along the fuel rod. This calculation was made by computing program MATLAB.
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Determination of vanillin using carbon paste electrode
Jarošová, Romana ; Zima, Jiří (advisor) ; Daňhel, Aleš (referee)
Title: Determination of vanillin using carbon paste electrode. Abstract: The aim of this work is the determination of vanillin by flow injection analysis (FIA) with electrochemical detection using carbon paste electrode (CPE) and spectrophotometric detection. Optimal conditions for determination of vanillin by the FIA were found. Under optimal conditions calibration dependences were measured in the concentraction range from 1·10-4 mol·l-1 to 2·10-7 mol·l-1 . The calibration dependences were evaluated using linear regression method. Comparable results were achieved for the determination of vanillin by FIA with electrochemical detection using CPE and for the determination of vanillin by FIA with spectrophotometric detection. Limits of detection were identical 1.7·10-7 mol·l-1 . Key words: vanillin, carbon paste electrode, flow injection analysis, electrochemical detection, spectrophotometric detection
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Silver amalgam electrodes in electroanalysis of selected agrochemicals
Daňhel, Aleš
Development and testing of novel non-toxic electrode materials, detection arrangements and analytical methods applicable in determination of selected agrochemicals is the main aim of this Ph.D. Thesis. New working electrodes based on silver solid amalgam paste (AgSA-PE) with organic pasting liquid and other based on crystallic silver amalgam (CAgAE) were developed, their electrochemical behaviour investigated and further used in voltammetric determination of widespread and toxic environmental pollutant 4-nitrophenol (4-NP). This analyte could be determined by DPV at AgSA-PE with limit of detection (LD) 1×10−6 mol l−1 and using CAgAE with LD 4×10−7 mol l−1 , both in 0.2 mol l−1 acetate buffer pH 4.8. Attempts to decrease LDs by utilization of adsorptive stripping voltammetry were not successful in either case. Crystallic silver amalgam was also successfully used for construction of microcylindric flow-through cell and tested for amperometric determination of nitrophenol mixture in HPLC-ED system. Both novel electrodes were found to be suitable alternatives to toxic mercury electrodes and the CAgAE seems to be promising working electrode for flowing systems. Method for sample preparation and voltammetric determination of broad-spectrum herbicide Glyphosate in contaminated soil samples was also...
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Utilization of Catalytic Hydrogen Evolution in Electrochemical Analysis of Nucleic Acids
Fojta, Miroslav ; Daňhel, Aleš ; Špaček, Jan ; Havran, Luděk ; Šebest, Peter ; Orság, Petr ; Pivoňková, Hana ; Vosáhlová, J. ; Schwarzová-Pecková, K.
Catalysis of hydrogen evolution (CHE) at mercury in the presence of proteins was discoverd shortly after the introduction of polarography. In contrast, unmodified nucleic acids have not been reported to produce distinct signals due to the CHE to date. Chemically modified nucleic acids bearing certain extrinsic groups produce analytically useful signals due to hydrogen evloution catalyzed by the respective modifications. These species include (a) transition metal complexes, and (b) non-metal catalytically active organic moieties. In addition, the CHE has been reported to be invoved in guanine reduction process at the mercury-based electrodes.
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Electrochemical Reduction and Oxidation of Nucleic Acids Bases and their Analogues: a Brief Overview
Fojta, Miroslav ; Špaček, Jan ; Dudová, Zdenka ; Pivoňková, Hana ; Daňhel, Aleš ; Fojt, Lukáš ; Havran, Luděk
Nucleic acids are known as electroactive biomacromolecules containing electrochemically reducible or oxidizable constituents. Nucleobases cytosine, 5-methylcytosine, adenine and guanine can be reduced in aqueous media on mercury or silver amalgam electrodes. Oxidation of all natural nucleic acids bases (in addition to the above mentioned ones, also uracil and thymine) was demonstrated using various types of carbon electrodes. Some of synthetic nucleobases or nucleotide analogues (e g., 7-deazapurines, cytidine analogues used as epigenetic modulators, etc.) exhibit specific electrochemical properties that differ from those of the parent bases and can be utilized to determine the given substance in the presence of natural nucleic acids or their components.
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Electrodeposited Coatings at ITO/FTO Enhancing their Applicability in Electroanalysis
Daňhel, Aleš ; Fojta, Miroslav
Recent possibilities of modification of transparent electrodes based on indium-tin oxide and/or fluorine doped tin oxide by electrodeposited coatings enhancing their electrochemical applicability in electroanalysis are discussed in this work. Ordered mesoporous silica and/or chemically functionalized mesoporous silica thin films may serve, among the common utilization in solid phase extraction, as protective layer of the electrode surface against its fouling and/or as molecular sieve permeable for small molecules and blocking large ones (DNA, proteins, etc.). Furthermore an electrodeposition of organic modifiers and/or metal (nano) particles inside of the ordered silica nanochanels together with direct electrodeposition of selected metal (nano) particles onto selected conductive transparent supports are presented here as well.
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Amalgam Electrodes Pretreatment and Electrochemical Analysis of DNA
Daňhel, Aleš ; Fojta, Miroslav
Mercury meniscus silver solid amalgam electode (m-AgSAE) represents the most suitable and perspective alternative to mercury electrodes which excel in sensitivity to biopolymers and their structural changes. This work briefly summarizes factors influencing electrochemical analysis of DNA at mercury and amalgam electrodes and it is mainly devoted to development of suitable pretreatment procedure, which could securte repeatable and reliable measurements of DNA at m-AgSAes. The results are essential for further utilization of amalgam electrodes in developement of biosensors, since DNA samples are very strongly adsorbed at the electrodes, and none pretreatment procedure was found to be successful in their complete desorption.
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Limitations and Possibilities of Nanostructurized Silver Amalgam
Daňhel, Aleš ; Šebest, Peter ; Vidláková, Pavlína ; Ligmajer, Filip
Variability of silver amalgam offers a row of opportunities for its application in electrochemical and spectroelectrochemical methods, thanks to its chemical, mechanical, electrochemical and spectrometric properties. This work briefly revews preparation possibilities and limitations of nanostructurized crystalas and nanopartices pf silver amalgam at different forms of carbon metals (Ag, Au, Pt) and transparent materials (ITO, FTO). These detection sysytems are in the scope of ongoing systematics research with the potential to indevelopment of novel working (micro)electrodes and spectroelectrochemical cells, potentially utilizable in modern (bio)analytical applictions.
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