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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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Interaction between amphiphilic fluorescent probes and hyaluronan
Střondalová, Hana ; Vala, Martin (referee) ; Mravec, Filip (advisor)
This bachelor thesis dealt with studying the interaction of amphiphilic fluorescent probes with hyaluronan because these probes could significantly help in clarifying the links between hyaluronan and surfactants. This complex could be a great benefit in targeting drug distribution. This thesis was focused on the interaction between hyaluronan and amphiphilic fluorescent probes – specifically with dodecylacridine orange. First explored was the interaction with hyaluronan, and then with the hyaluronan – surfactant system. Cetyltrimethylamonium bromide was selected as surfactant. Samples were examined using fluorescence spectroscopy. Emission and absorption spectrum of dodecyl acridine orange was measured. This experiment was based on the hypothesis that dodecylacridine orange forms dimers as acridine orange and nonylacridine orange. It was found that in a system of hyaluronan-probe, dodecyl acridine orange was pushed out of the complex by cetyltrimethylamonium bromide, which was bounded instead. Surfactant interacts with hyaluronan binding positions - with carboxyl groups.
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Energetic interactions between electon-donors and acceptors for photovoltaic solar cells
Hrabal, Michal ; Heinrichová, Patricie (referee) ; Vala, Martin (advisor)
The aim of this bachelor thesis is to study a charge transfer between materials that could be used for development of new organic solar cells. The charge transfer is studied by a quenching of fluorescence. The thesis is divided into theoretical and experimental part. The basic knowledge needed for correct interpretation of measured data is summarized in the first part. Special attention is paid to the photoinduced electron transfer. Then, the processes of conversion of solar energy into electric energy and properties of potential materials are also discussed. Architecture of organic solar cells is mentioned in the end of the work. The practical part contains the study of quenching of fluorescence by fullerene derivatives and compares the efficiency of quenching to standard materials.
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Preparation of luminescent nanoparticles for 3D imaging
Smolka, Rastislav ; Hrabal, Michal (referee) ; Vala, Martin (advisor)
The aim of this bachelor thesis was to study a suitable methodology for the preparation of fluminiscent nanoparticles and to characterize their optical properties associated with various physical properties of environment. Also, their potential use as a means of monitoring biological preparations in 3D microscopy using multiphoton absorption. In particular, we deal with nanoparticles prepared from N,N-diphenylamino-2,5-diphenyl-1,4-distyrylbenzene cyanide and their fluorescence and absorption spectra. Using the dynamic light scattering method and fluorescence spectroscopy, the dependence of the size of the prepared nanoparticles, the change in their fluorescence properties and the change in the quantum yield is observed, depending on the changing environmental properties. Data from multifoton absorption measurements demonstrate that this substance responds to multifoton excitation. It has been shown that this substance retains its unique fluorescence properties also in the form of nanoparticles and thus appears to be a suitable candidate for the observation of biological preparations using multifoton fluorescence microscopy. Therefore, the continuation of this work could be the mere determination of the total multifoton absorption cross section of these prepared nanoparticles.
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Optimalization of printing methods of organic semiconducting layers preparation
Ehlich, Jiří ; Vala, Martin (referee) ; Salyk, Ota (advisor)
Electrophysiological biosensors enables a novel way to measure electrical activity of biological structures both in-vitro and in-vivo and represents valuable alternative to current cellular activity measuring methods. Within this work we will be focusing on development of organic semiconductor (PEDOT:PSS) based Organic Electrochemical Transistors (OECTs) and optimization of material printing methods used in their development. These transistors are meant to be able to transfer electrochemical signals within the cell membrane to electrical signal. Such sensors should be used for cytotoxicity testing of chemicals and potential drugs on cardiomyocytes. Main benefits of OECTs are in their higher sensitivity thanks to their ability to locally amplify electric signals, better noise-signal ratio and outstanding biocompatibility. Their development is undemanding and inexpensive due material printing methods and materials processable at room temperatures.
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