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Mineralogical analysis of historical paintings
Čermáková, Zdeňka ; Hradil, David (advisor) ; Kanický, Viktor (referee) ; Artioli, Gilberto (referee)
Historical painted works of art have a very complex inner structure. The period painting technique led to the execution of a ground layer followed by several layers of underpainting and a top paint layer, over which a layer of glaze has been applied to increase the resistance to external wear. Each of these colour layers is composed of a dye or a pigment (or their mixture) bound by organic binder. Throughout the history, pigments were commonly prepared from minerals, either extracted from natural deposits or created artificially. In these heterogeneous layers containing both inorganic and organic components, undesirable degradation changes either driven by processes taking place directly in the colour layer or influenced by external agents may occur. Mineralogical approach, which focuses primarily on the structure of studied pigments, helps in the clarification of the occurring processes, in the determination of conditions leading to degradation as well as in the identification of original/degradation phases. Furthermore, it can be profitably applied in the micro- analysis of mineral pigments present in tiny micro-samples obtained from works of art, contributes to the artwork's provenance/authorship studies and the determination of regional provenance of the employed mineral pigments. This Ph.D....
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Optimisation of Isolation Procedure and Characterization of Amorphous PHB granules
Kratochvíl, Zdeněk ; Obruča, Stanislav (referee) ; Kalina, Michal (advisor)
First artificial PHB granules were prepared under the terms of this thesis. The effect of used PHB solvent, ultrasonic bath temperature and time, solvent evaporation temperature and stabilizing agent nature was investigated using dynamic and electrophoretic light scattering. The most proper parameters were demonstrated at samples which were prepared by dissolving of PHB in chloroform, stabilizing with CTAB or lecithin, ultrasonifying at 35 °C followed by chloroform evaporating at 60 °C. Based on ATR-FTIR and Raman spectroscopy results, it was found out that PHB within the artificial granules were in crystalline form. The native PHB granules were isolated from Cupriavidus necator using either lysosyme, deoxyribonuclease and cell disruption by ultrasonification or digestion with alcalase, SDS and EDTA. Granules obtained by both isolation procedures were characterized by ATR-FTIR, Raman spectroscopy, light scattering techniques and DSC. According to the analyses results, the second mentioned procedure turned out to be more effective for obtaining the polymer in amorphous state. Furthermore, the polymer within granules recovered by using this procedure was thermally more stable. Last but not least, the native PHB granules samples were exposed to effect of acetone, lipase and sodium hypochlorite, assuming that polymer crystallinity should be increased by these chemicals in varying degrees. The highest degree of crystallinity was achieved after their treatment with lipase.
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Infrared Spectroscopy of Multiferroics
Goian, Veronica ; Kamba, Stanislav (advisor) ; Javorský, Pavel (referee) ; Dubroka, Adam (referee)
Infrared Spectroscopy of Multiferroics Author: Veronica Goian Institute: Department of Dielectrics, Institute of Physics of the Academy of Sciences, Na Slovance 2, 182 21 Prague 8 Abstract: We have investigated numerous multiferroic and magnetoelectric materials mainly using infrared (IR) spectroscopy. Nevertheless, the studies were frequently combined with radio-frequency, microwave, THz, Raman and structural measurements provided by our colleagues, as well as by magnetic and elastic investigations, where we participated. Our main aim was the complex study of quantum-paraelectric antiferromagnet EuTiO3 in the form of crystals, ceramics and thin films. Near 300 K we have discovered an antiferrodistorive phase transition from cubic mPm3 to tetragonal I4/mcm structure in bulk EuTiO3 and explained its low-frequency dielectric properties by anomalous polar phonon behavior. Large and anisotropic magnetodielectric effect, which we found in EuTiO3, was successfully explained and experimentally confirmed by observation of tuning of phonon frequency with magnetic field. Our IR studies of tensile strained EuTiO3 thin films revealed a displacive ferroelectric phase transition near 250 K. Our American colleagues revealed the ferromagnetic order below 4.2 K in the same strained EuTiO3 thin film. In such way we have...
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Fourier transform infrared spectroscopy: application in a study of transient species in discharge and ablation plasma
Kubelík, Petr ; Civiš, Svatopluk (advisor) ; Wild, Jan (referee) ; Rohlena, Karel (referee)
The present dissertation consists of two thematically related parts. The first one (includes two publications) deals with the study of chemical pro- cesses and spectroscopy of highly reactive particles produced in the discharge plasma. This part includes the analysis of ro-vibronic CN radical transitions in the infrared region and the study of chemical reactions in pulsed dischar- ges. The discharge was used as a tool for research of decomposition of simple precursors (acetonitrile, formamide and BrCN) and the subsequent formation of intermediates and reaction products in plasma. The obtained experimental results were interpreted using a numerical model developed in context of this work and used to simulate the kinetics of the studied systems. The second part (includes seven works) is aimed at high-resolved spectro- scopy of metals in the ablation plasma. A total of six different metals were studied: Au, Ag, Cu, Cs, K and Na. The main motivation for spectroscopic research on metals in the infrared region is to obtain information on atomic metals transitions, which are particularly important for astronomical identi- fication of lines in the spectra of stars and their spectroscopic assignments. Each publication contains a summary of the analyzed atomic transitions of which a considerable portion had not...
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Spectroscopic Investigation of Lattice Dynamics in Multidomain Ferroelectrics
John Vakkechalil, Elizabeth ; Hlinka, Jiří (advisor) ; Hlídek, Pavel (referee) ; Hehlen, Bernard (referee)
Title: Spectroscopic investigations of lattice dynamics in multidomain ferroelectrics Author: Elizabeth Vakkechalil John Department: Department of Condensed Matter Physics Institution: Department of Dielectrics, Institute of Physics, AVČR, Na Slovance 2, Praha 8, 182 21, Czech Republic. Supervisor: Ing. Jiří Hlinka, PhD., Department of Dielectrics, Institute of Physics, AVČR., Na Slovance 2, Praha 8, 182 21, Czech Republic. Consultants: RNDr. Stanislav Kamba CSc., Ing. Ivan Gregora CSc. Fyzikální ústav AVČR, Na Slovance 2, Praha 8, 182 21, Czech Republic. Abstract: Lead based ferroelectric perovskites exhibit attractive physical and structural properties. Ferroelectric domains are known to have a very essential impact on dielectric and piezoelectric properties of ferroelectrics. Tailoring of domain structures allows to change the macroscopic symmetry of the material and to purposely modify its average tensor properties. Ferroelastic domains play also a key role in physics of epitaxial ferroelectric films. Here we studied signature of domain structure in PbTiO3 thin film grown by metalorganic chemical vapor deposition technique on different substrates, namely LaAlO3, MgO, NdGaO3, SrTiO3 (100), SrTiO3 (110), SrTiO3 (111) doped with 0.5% Nb and LSAT. Certain aspects of domain structure can be...
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Application of vibrational spectroscopy to analysis of artwork - mortars
Křížová, Iva ; Němec, Ivan (advisor) ; Hynek, Radovan (referee)
The aim of this work was to determine the possibility of identifying the protein and lipid additives, such as blood, gelatin, curd, lard or eggs, in the model samples of lime based mortars using infrared spectroscopy. We have focused on the reflectance techniques of infrared spectroscopy, and we proved that by these methods can be determined the presence of additives, down to tenths percent by weight. Detailed resolution of lipid and protein additives can be achieved only for samples containing at least one weight percent of additive. There were not observed any spectral changes which can be correlated with performed curing and aging of prepared model samples.
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Methods for determination of hyaluronan
Černá, Lucie ; Venerová, Tereza (referee) ; Pekař, Miloslav (advisor)
This thesis deals with a summary of individual method for determining of hyaluronan concentration, especially in aqueous solutions. Selected methods were compared to their functionality in university workplace. Any functional methods may be used for many purposes in university workplace in research of materials based on hyaluronan. It has been studied usability to assess residual content of hyaluronan in supernatant of gel formed from hyaluronan and surfuctant, in this thesis. We choosed sptectrophotometric methods, especially with UV spectroscopy and IR spectroscopy. Two precipitation methods using alcian blue were also tested. As the most reliable, the least demanding and specific method seems to be the method using IR spectroscopy, thanks to it we are able to determine the concentration of HA from 0.01 %. With this method, it has been found, that if there will be located some amount of HA in supernatant, it will be below the detection limit of assay. The remanining methods were modified to help determine the concentrations of HA, but works only in aqueous solutions. A possible variation for determination of very low concentrations of HA may be the method using ELISA kits. However their cost is higher than the above-mentioned methods.
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Testing of commercial rubber sealing components exposed to different ambient conditions
Jančaříková, Marie ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
Diploma thesis studies the effect of temperature (75 and 105 °C) and the effect of 3 kinds of liquids (silicone and hydraulic oil and coolant) at room temperature and at 105 °C on change of the structure of 3 species butadiene-acrylonitrile (NBR) seals (o-ring and two types of bolts). The seals are inspected by the thermogravimetric analysis, differential scanning calorimetry and infrared spectroscopy, the influence of 105 °C on the o-rings is also evaluated in terms of changes in tensile properties. The greatest changes in the composition and structure are observed on o-rings particularly due to temperature of 105 °C, there was a significant reduction in dilatability and an increase in stiffness and glass transition temperature. The root cause is the surface and centre additive decomposition and oxidation. The bolts have suffered from decomposition of the protective surface layer and the additives in the centre, structural change was minor. Exposure to 75 °C has resulted in a gradual loss of low molecular weight substances. Liquids at room temperature didn‘t affect the structure of the seals, at 105 °C it caused a loss of weight due to decomposition of the protective surface layer and release of additives and the products of their decomposition. Results showed that the common use of the NBR seals at 105 °C is unsuitable, at 75 °C it leads to gradual changes, loss in mechanical and sealing properties.
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