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Kinetic study of excited state proton transfer in polymer-surfactant system
Bačová, Jana ; Vala, Martin (referee) ; Mravec, Filip (advisor)
In this bachelor thesis were studied interactions between hyaluronic acid and cationic septonex by steady-state and time-resolved fluorescence with fluorescence probes pyrene and 1-naphthol. At first was determined critical micelle concentration of septonex. In the case of both fluorescence probes was studied area below and above critical micelle concentration. It was found, that 1-naphthol undergo very fast deprotonation in aqueous solution, while in the present of micelles the rate of deprotonation is c significantly retarded. In the system of hyaluronic acid – septonex it was observed, that formation of aggregates occurs at lower concentrations than in the system without hyaluronic acid. Molecules of probe are probably distributed between hyaluronic acid – septonex aggregates and free micelles above critical micelle concentration.
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Development of Light Emitting Electroluminescent Device by Means of Material Printing
Hrabal, Michal ; Syrový,, Tomáš (referee) ; Boušek, Jaroslav (referee) ; Vala, Martin (advisor)
Cílem této práce je vývoj světelného zdroje založeného na technologii tlustostěnného elektroluminiscenčního panelu napájeného střídavým napětím (ACPEL). V současné době se jedná se o jedinou technologii založenou na metodách materiálového tisku vhodnou pro přípravu velkoplošných, flexibilních a vzorovaných zdrojů světla. Důraz je v této práci kladen na představení, prozkoumání a odstranění typických problémů, které jsou spojovány s touto technologií. Tyto problémy jsou omezený odstín barvy emitovaného světla a dlouhodobá stabilita elektroluminiscenčního prvku, který je vystaven vlivům prostředí. Rešeršní část dizertační práce je zaměřena na představení a identifikaci depozičních technik, vhodných pro reprodukovatelnou přípravu ACPEL panelů. Dalším cílem je identifikace fyzikálních parametrů, vhodných pro charakterizaci velkoplošných zdrojů světla. Praktickým cílem práce je nalezení vhodné metodologie pro popis a charakterizaci panelů, jakožto plošných světelných zdrojů. Fotometrická veličina jas L a spotřeba elektrické energie P byly vyhodnoceny jako vhodné parametry, určující aplikaci ACPEL panelů. Na modrém panelu bylo dosaženo maximální hodnoty jasu L = 133 cd•m2 při napětí Upp = 500 V a frekvenci f = 1000 Hz. Hodnoty spotřeby elektrické energie, vztažené na jednotkovou plochu panelů zkoumaných v této práci, jsou (7±3) mW. Tyto dosažené hodnoty dělají ze světelných zdrojů založených na ACPEL technologii zajímavé kandidáty pro různé aplikace. Vlivu rostoucí amplitudy a frekvence budícího napětí na dlouhodobou stabilitu panelů je důležitým cílem této práce. Pro popis stability byly zavedeny parametry L50 and L75. Bylo zjištěno, že rostoucí frekvence budícího napětí zkracuje životnost panelů. Laminovaný panel napájený napětím s přibližně trojnásobně vyšší frekvencí vykazoval přibližně třetinové hodnoty parametrů L50 a L75. Nejvyšších hodnot stabilitních parametrů dosahoval panel enkapsulován mezi skleněné pláty – přibližně sedminásobnou hodnotu oproti laminovanému panelu s trojnásobnou frekvencí. Optimální stability panelů lze dosáhnout při nastavení frekvence v rozmezí 400–800 Hz a zapouzdřením mezi sklo. Úzká paleta odstínů barev emitovaného světla je jeden z typických problémů, který dále zkoumán v dizertační práci. Tato práce zkoumá nadějnou metodu, přídavek vhodného materiálu pro konverzi barvy (CCM). Nový derivát diketopyrrolopyrrolu (DPP), absorbující v modré oblasti, byl přidán k modrému fosforu a byl pozorován sedminásobný narůst hodnot absolutního spektrálního ozáření v oblasti vlnových délek odpovídajících maximální emisi CCM materiálu. Jednoduchost přípravy vyvinutých zdrojů světla spolu s velmi nízkou spotřebou a vysokou dobou života dělají z ACPEL panelů zajímavé kandidáty pro podsvícení prvků například v automobilovém průmyslu, pro dekorativní osvětlení, pro „branding“ – zvýraznění reklamních značek.
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Preparation of organic electrochemical tranzistors for biosensorics
Ehlich, Jiří ; Vala, Martin (referee) ; Salyk, Ota (advisor)
The goal of this thesis is to describe the process used in preparation of organic electrochemical transistors thus biosensors for testing potential drugs aimed for cardiomyocytes. Then explore some physical properties of developed sensors such as adhesion of materials used, conductivity of developed structures and stability of developed structures in various water environments. As primary technology used for creating our OECTs was used inkjet printing of special inks with electrical properties on PET and PEN substrate cured with special treatment before and after printing. This thesis results in complete view on technology and development of biosensors we had created.
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Study of humic and fullvic acids by excitation emission matrix method
Enev, Vojtěch ; Vala, Martin (referee) ; Fasurová, Naděžda (advisor)
A bachelor thesis was focused on fluorescence measurement by emission-excitation matrix method (EEM) and finding of the main fluorophores of soil humic and fulvic acids samples. The results of the position of the main peak of fulvic acid isolated from soil type Cambisol were compared and were similar to the position of Elliot soil FA standard II. For determining of secondary peaks of fulvic acids the synchronous method (3D SFS) at lower wavelengths was used.
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Preparation of white-electroluminescent panel
Guricová, Patrícia ; Novák, Vítězslav (referee) ; Vala, Martin (advisor)
The aim of this work is to prepare white emitting electroluminescent device using printing techniques. Preparation options are discussed in order to minimise reabsorption in the phosphor layer and thus increase the overall radiation intensity. Model devices were prepared, the active layer of phosphor printed in a pattern of stripes and circles. The impact of the applied voltage and frequency was studied on these devices. It has been shown that, in terms of white emission, it is better to use the patterns compared to the phosphor mixture. The ratios of emission intensities of both phosphors are more even, therefor closer to the white light. The output of this work is model designed to determine the necessary frequency area for obtaining the white emission of ACEL device.
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Adaptation of the time resolved optical spectroscopic aparatus
Koutný, Jan ; Šedina, Martin (referee) ; Vala, Martin (advisor)
The theme of the bachelor's thesis is an assembling of an apparatus for measurement of transient absorbance by flash photolysis and a testing its functionality by detecting of benzophenon triplet states absorbance. The theoretical part focuses on basic principles of optic spectroscopy, flash photolysis and an instrumentation used in spectroscopy. Special attention was paid to the components used for constructing of the experimental apparatus. The practical part concentrates on a realization of the apparatus itself, a testing of basic experimental dependences and a determining of time dependence of transient absorbance of triplet states.
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Microelectrode arrays for mioelectronic
Bráblíková, Aneta ; Vala, Martin (referee) ; Salyk, Ota (advisor)
Organic electronic biosensors are developed as suitable devices that can transform electrochemical processes within the cell membrane into an electronic signal and enable to measure electrical activity of excitable cells and tissues both in vitro and in vivo and thus represent valuable alternative to current cell monitoring methods. In this work we focus on the fabrication of electrophysiological sensors based on organic semiconductors printed by the material printing method. Microelectrode arrays (MEAs) are active components of the device, which can monitore cellular activity and above that stimulating cells with electrical pulses. The proposed platform should be used for cytotoxicity of potential drugs especially on cardiac cells (cardiomyocytes). The experimental part focus on specific production processes of platforms, which were prepared in the laboraty with emphasis on biocompatibility and conductivity of device.
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Belt conveyor for quartz sand
Vala, Martin ; Pokorný, Přemysl (referee) ; Malášek, Jiří (advisor)
The aim of this bachelor thesis is to design a belt conveyor according to the assigned parameters: conveyed material, conveyor capacity, axial distance between the drums at both ends and height difference. On the basis of these parameters a functional calculation is conducted in accordance with the standard ČSN ISO 5048. The main dimensions of the conveyor were determined as well as suitable components further described in the thesis. All necessary parts were designed. The thesis also includes strength calculation of drive shaft, calculation of bearing durability used for the drive shaft and calculation of safety factor in relation to limit state of bolt strut stability of tension mechanism. The conclusion part is focused on the evaluation of the designed conveyor when used for materials of different grain size and humidity. Required designed drawings are annexed.
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Materials with FR/NIR photoluminiscence
Chovanec, Filip ; Kratochvíl, Matouš (referee) ; Vala, Martin (advisor)
This bachelor thesis is focused on issues of materials, whose fluorescence maximum is located in regions of the far-red (FR), which is in range from 700-800 nm or near-infrared (NIR), from 800-2500 nm, electromagnetic radiation. Materials, which this thesis is focused on, are organic molecules with charge transfer (CT) system. They are based on electron-donor and electron-acceptor groups located on the opposite sides of the same molecule. Diphenylamine behaves as electron-donor. This moiety is connected to different batch of atoms, which figure as electron-acceptor group. Connection is formed by -conjugated bridge of diphenyl stilbene or dixylil stilbene. Such a variable system has an optionally adjustable magnitude of charge transfer phenomenon, and it is reflected in the fluorescence maximum. Knowledge about fluorescence of these molecules, phenomena accompanying and outrunning this radiation, was acquired through the theoretical research. Strategies, how to set such a DA system or how to set up molecules with FR/NIR fluorescence were also obtained. Practically, characterization and dependence of fluorescence maximum on structure of these molecules, as well as dependence on solvent were determined by fluorescence spectroscopy. Photoluminescence quantum yield was calculated from emission and excitation spectra and studied how structural changes changed values of this quantum yield and fluorescence lifetime too. The result of the bachelor thesis was the finding, that the stronger the charge transfer phenomenon occurs in the molecule, the greater bathochromic shift of emission spectra was observed. At the same time, it was discovered that it was the case of liquid sample, solid samples had shown smaller bathochromic shift.
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