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Laser ablation of calcium and aluminium atoms as a particle source for ion trap
Grim, Jakub ; Pekař, Zdeněk ; Pham, Minh Tuan ; Číp, Ondřej
Laser ablation is an effective method for generating particles from a variety of materials, including those with high evaporation temperatures such as aluminum. The use of high-energy laser pulses enables controlled evaporation of the material and the creation of an ablation crater. Successful results have been obtained in a pilot setup for the generation of neutral calcium and aluminium atoms by laser ablation. The method is being compared with thermal resistance oven in order to optimize the prosec generation of these particles. Subsequent spectroscopic measurements on the generated atoms are performed to optimize the absorption and emission of photons for subsequent ionization in the ion trap. A study of the transitions of neutral Ca and Al atoms shows that laser ablation provides a more efficient generation of atoms with the possibility of greater control over the process.
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Influence of polysaccharides on caffein absorption from beverages
Osecká, Karolína ; Márová, Ivana (referee) ; Pekař, Miloslav (advisor)
This bachelor thesis was focused on investigation of the interaction between the polysaccharide sodium hyaluronan (HA) and the alkaloid caffeine (CAF). The reason why this thesis was focused on study of aqueous solutions of hyaluronan with caffeine is that presence of polysaccharide can slow down the realising from hyalurona-caffeine complex. At first, it was determined whether the photophysical properties of caffeine reacts in different polarity solvents. Based on these results was studied the interaction of caffeine and hyaluronan using the fluorescence. Emission and excitation spectra of caffeine were observed. The HA of molecular weight of 1.7 MDa were chosen for the study of the interactions with the caffeine of concentration the caffeine contained in coffee. The results of interaction that would result to influence the emission properties of CAF, not show. In acidic solutions leading to the formation of various shapes of HA and by centrifugation it was determined whether HA in this form interacts with CAF, which was shown to decrease the absorbance of the supernatant in the CAF. The solution and the mixtures were measured in four types of environment in hydrochloric acid solutions at different pH. The influence of constant addition of caffeine and the HA of molecular weights of 1.7 MDa with different concentrations in different acidic solutions. As a part of the work was to determine how hyaluronan behaves in strongly acidic solution. And then determine the pH in model gastric juices after intake of Coca Cola and Kofola. The obtained results can be used as for description of the behavior of caffeine in the presence of selected polysaccharide.
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Interactions and aggregation in hyaluronan-aminoacid-surfactant systems
Venerová, Tereza ; Velebný, Vladimír (referee) ; Pekař, Miloslav (advisor)
The effect of native hyaluronan addition on CMC of excluded surfactants (Tween 20, BETADET THC 2, SDS, CTAT a CTAB) in physiological solution (0,15 M NaCl) has been investigated by fluoresence spectroscopy with Pyrene and Nile red as probes. The greatest influence on CMC has been observed in systems with cationic surfactant. System of cetyltrimethylamonnium bromid has been closely studied. Solubilization experiments with a hydrophobic dye Sudan red has been realized and aggregation number of this system has been determinated via fluorescence quenching with cetylpyridinium chloride as quencher and Pyrene as fluorescence probe. Addition of hyaluronan (native or hydrophobicaly modified) reduces aggregation number of system.
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Aggregation processes in amphiphil-polymer system
Šejnohová, Michaela ; Márová, Ivana (referee) ; Pekař, Miloslav (advisor)
This Bachelor´s thesis is focused on the exploration of polyelectrolyte-surfactant system by fluorescence spectroscopy with pyrene as fluorescent probe. Cationic cetyltrimethylammonium bromide (CTAB) was used as a surfactant. Native hyaluronan was used as polyelectrolyte. Hyaluronan was used in one constant molecular weight and one constant concentration. The whole system was prepared in an aqueous environment. Interactions were studied in area between critical aggregation concentration (CAC) and critical micelle concentration (CMC). The influences of the concentration of pyrene and the effect of the way of the samples preparation on aggregation behavior were also studied. It was found that above the critical aggregation concentration exists an area where stable properties of aggregates can be found. The concentration of pyrene has a major effect on the fluorescence properties of the system. Preparation of samples affects the aggregation of the system. At higher surfactant concentrations, above the stable area, was observed phase separation and gel formation.
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Influence of the temperature on hydrophobic domain quality in a biopolymer-surfactant system.
Hnyluchová, Zuzana ; Kopuletá, Ema (referee) ; Mravec, Filip (advisor)
The temperature dependence on polarity has been investigated by fluorescence spectroscopy with pyrene as a probe. Pyrene was chosen thanks to its unique sensitivity to polarity of the medium. As a biopolymer was chosen 73 kDa and 1,4 MDa hyaluronic acid. Emission spectra of pyrene were measured as a function of temperature in aqous solution of CTAB in a presence and absence of sodium chloride. The results show, that the addition of specific concentration of hyaluronic acid to the sample with CTAB, mostly doesn´t have effect to change increasing/decreasing slope of polarity with the temperature.
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Use of thin layer chromatography for fractionation and characterization of organic matter isolated from alginite
Solanský, Pavel ; Sovová, Šárka (referee) ; Enev, Vojtěch (advisor)
This diploma thesis is focused on the study of structure and physicochemical properties of organic fractions of humic substances, which were obtained by the method of thin-layer chromatography. Humic substances, which were used in this study, were isolated from a sample of Slovak alginite based on the procedure of the International Humic Substances Society (IHSS). The following analytical techniques were selected for the characterization of isolated humic substances: thermogravimetric and elemental analysis, molecular absorption spectroscopy (UV/Vis), Fourier transform infrared spectroscopy (FTIR) and steady-state fluorescence spectroscopy. Each organic fraction of humic substances were characterized by molecular absorption spectroscopy (UV/Vis) and steady-state fluorescence spectroscopy. Using steady-state fluorescence spectroscopy, humic substances were found to be composed of fluorophores of humic and non-humic (protein) character. Organic fractions corresponding to the humic fluorophores were characterized by a higher content of oxygen substituents on the aromatic nukleus, a higher degree of aromaticity and also a higher molecular weight. The aim of this diploma thesis was to design and optimize the process of organic matter fractionation for the purpose of detailed understanding of the structure and properties of humic substances, which were isolated from the sedimentary rock alginite. Based on this, the practical applicability of the thin layer chromatography method to significantly reduce the molecular heterogenity of the studied humic substances was evaluated.
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Stability of vesicular complexes against changes in their concentration
Velichová, Veronika ; Marková, Kateřina (referee) ; Mravec, Filip (advisor)
This bachelor thesis is focused on the stability of vesicular systems that consist of ion pair amphiphile. These catanionic vesicles were prepared from single-chained surfactants CTAB cetyltrimethylammonium bromide) and SDS (sodium dodecyl sulphate), which were stabilized by adding double-chained surfactant DODAC (dimethyldioctadecylammonium chloride) with 43 mol.% cholesterol. The aim of the thesis was to verify the stability of vesicular systems against changes in their concentration. For the measurement, a concentration series was prepared by diluting vesicles with deionized water. The stability was evaluated by dynamic (DLS) and electrophoretic (ELS) light scattering measurements at weekly intervals for four weeks. By DLS method were determined the average values of the size of vesicles and their changes during the measurement, the method ELS provided the information about changes of charge with different concentration in time. Samples with a higher concentration, i.e. no dilution till tenfold dilution of the vesicle solution, were marked as stable, higher values of average sizes and lower values of zeta potential were measured at solution with lower concentrations, according to which such diluted vesicles can be described as unstable. There were also visual observations made, but no visible aggregation in the solutions was observed. Furthermore, the aggregation behavior of the vesicles was observed by fluorescence spectroscopy using pyrene as fluorescent probe.
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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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Interactions between hyaluronan and cetrimide
Adamcová, Zuzana ; Sedláček, Petr (referee) ; Mravec, Filip (advisor)
Interactions between hyaluronan and cationic Cetrimide were studied using fluorescence spectroscopy and turbidimetry in model physiological solution (0,15 M NaCl) and water. Results obtained in water showed strong electrostatic interactions before reaching CMC of the surfactant, which were screened in presence of salt due to high ionic strenght of the solution. Behavior of Cetrimide-hyaluronan systems was compared with the pure TTAB in equivalent system. It was found, that changes in Cetrimide-HA system occure at lower concentrations of the surfactant than in TTAB-HA system. This was probably caused by presence of small amount of CTAB in Cetrimide.
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Interaction in ionic surfactant/non-ionic surfactant/polyelectrolyte system
Pihíková, Dominika ; Sedláček, Petr (referee) ; Mravec, Filip (advisor)
The interactions in an ionic surfactant/non-ionic surfactant/polyelectrolyte system have been studied in this bachelor thesis. The value of critical micelle concentration of cationic didecyldimethylammonium chloride (DDAC) has been determined in three different mediums by fluorescence spectroscopy using Pyrene, Perylene and Nile red as probes. The CMC value of non-ionic octylphenol ethoxylate (Triton X-100) has been determined using Pyrene and Perylene as probes. The aggregation behavior of non-ionic and ionic surfactant with addition of polyelectrolyte poly(sodium4-styrensulfonate) (PSS) and native hyaluronan in aqueous solution has been investigated using Pyrene as a probe. Aggregation number in system of ionic/non-ionic surfactant has been determined by a fluorescence quenching with cetylpyridium (CPC) as a quencher and Pyrene as a fluorescence probe. Interactions in ionic surfactant/non-ionic surfactant/polyelectrolyte system were observed. This result was proved by double sigmoid Boltzman´s type curve. The addition of low molecular as well as high molecular hyaluronan had no significant effect on CMC value of the system.
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