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A novel AAS atomizer based on a dielectric barrier plasma discharge
Novák, Petr ; Kratzer, Jan (advisor) ; Kanický, Viktor (referee)
Atomization of arsine in a novel hydride atomizer for atomic absorption spectrometry (HG-AAS) was thoroughly optimized. This plasma atomizer is based on a dielectric barrier discharge (DBD). Sensitivity and detection limit reached 0.48 s ng-1 As and 0.16 ng ml-1 As, respectively, under optimum atomization conditions (Ar discharge using a flow rate of 60 ml min-1 Ar, DBD power 17 W). Analytical figures of merit reached in DBD are comparable to those found in an externally heated quartz tube multiatomizer (MMQTA) that was chosen as a model of conventional approach to hydride atomization in HG-AAS. An extent of interferences (Se, Sb, Bi) during As determination was investigated comparing both MMQTA and DBD atomizers. The later one was found to be more resistant towards interferences. A simple preconcentration of As in a DBD atomizer was reached after oxygen introduction into the Ar plasma in the DBD resulting in analyte retention in the atomizer followed by its volatilization once the oxygen flow is switched off. Preconcentration efficiency of 100 % was reached and detection limit improvement by a factor of ten was achieved (0.01 ng ml-1 As, preconcentration period 300 s).
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Quantitative Structure-Retention Relationships of Salicylthioamide Derivatives
Kalužíková, Aneta ; Nesměrák, Karel (advisor) ; Sobotníková, Jana (referee)
The aim of the thesis is to study the relationship between the structure of N-benzylsalicylthioamide derivatives and their retention behavior in high-pressure liquid chromatography. Furthermore, the influence of various substituents on electron absorption spectra in ultraviolet spectral range was studied. All studied derivatives have two absorption maxima in ultraviolet spectral range at 260 nm and 293 nm. The substitution of an auxochrome on the acyl ring leads to bathrochromic shift and hyperchromic shift, especially of the first absorption maxima. The presence of an auxochrome on the amide ring leads to hyperchromic shift as well. HPLC reversed-phase chromatography, using XDB-C18 ZORBAX column and mobile phase with various composition of acetonitrile, was used to obtain retention times of the derivatives. Using this data, the correlation equations between retention factor (mobile phase with no acetonitrile), resp. slope of the dependence of the logarithm of retention factor on the volume fracture of acetonitrile in mobile phase, and partition coefficient octanol-water, resp. hydrophobic substituent constants, were derived. Key words: QSAR, HPLC, spectrometry, benzylsalicylthioamides
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Interactions between Schistosoma spp. and their hosts at the metabolome level
Kurečka, Martin ; Kameník, Zdeněk (advisor) ; Mikeš, Libor (referee)
The blood flukes of the genus Schistosoma are important parasites that cause serious chronic diseases in mammals, including humans, in tropical and subtropical countries. Treatment of these diseases is challenging; therefore, new molecular targets are still being sought for the development of vaccines and more effective drugs. To achieve this, better understanding of interactions between the parasite and the host at the molecular level is an important prerequisite. These processes can be studied by quantitative and qualitative determination of metabolite differences in healthy and infected individuals using metabolomics. The work represents a review of low molecular weight substances in tissues and body fluids of schistosome hosts, in which a change in concentration of metabolites putatively related to the infection was observed. Only metabolites with a hypothetical or known mechanism of these changes in the context of infection are covered. The thesis also includes a brief overview of basic methods of analytical chemistry, which are used in studies based on metabolomics. Key words: Schistosoma spp.; intermediate host; definitive host; spectrometry; metabolomics; low molecular compounds
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Shielding and detection of neutrons
Černý, Tomáš ; Šťastný, Ondřej (referee) ; Katovský, Karel (advisor)
The master’s thesis provides an overview of available neutron sources in terms of neutron yields and energy spectrum of emitted neutrons. Reactions of neutrons with matter, especially neutron scattering and radiation capture, are described. The possibilities neutron neutron detection and spectrometry are also described. The following experiment deals with a design of suitable shielding materials and the analysis of the moderated energy spectrum of neutron flux. The properties of the neutron field were measured using detection by activation. Subsequently, a simulation of the problem was performer in the MCNP program. In the end, the achieved results are compared and evaluated.
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Comparison of Calibration Methods for Determination of Quinine in Beverages
Handlová, Zuzana ; Nesměrák, Karel (advisor) ; Kozlík, Petr (referee)
The aim of this bachelor thesis is to compare three calibration methods used for determination of quinine in beverages performed by two instrumental methods. As the calibration methods, calibration curve method, standard addition method and spike were chosen. As the instrumental methods, UV spectrometry and RP-HPLC with UV and fluorescence detection were chosen. The calibration methods were compared in terms of accuracy, precision, and time consumption. The instrumental methods were compared in terms of accuracy. Five different tonic waters were chosen as authentic samples. The most precise results were provided by the calibration curve method. In terms of accuracy it was not possible to determine the most accurate calibration method. Spike was the least time-consuming calibration method. HPLC was more accurate compared to spectrometry. Key words: analytical calibration, spectrometry, high performance liquid chromatography, quinine
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Cs-137 content monitoring by spectrometric measurement in soil
LEPIČ, Daniel
The aim of the thesis is to compare the results from in situ spectrometry and laboratory determination of the area activity of Cs-137 in samples taken from uncultivated soils. To fulfil the goal, the research question has been determined: Are the results from in situ measurement of the area activity of Cs-137 in uncultivated soil comparable with the results from laboratory measurement of collected soil samples? The theoretical part of the work has been written based on research of book publications, foreign scientific articles and electronic sources, which deal with the issue of radioactivity and its impact on the environment and the principle of semiconductor gamma spectrometry. The practical part of the work deals with the spectrometric measurement using in situ method and the laboratory determination of the area activity of Cs-137 in the soil samples using a semiconductor gamma spectrometer. The measurement and the soil sampling took place in the territory of the Šumava National Park and its adjacent areas in Pilsen Region. There were selected five locations (Nová Hůrka, Prášily, Srní, Nový Brunst and Hadí vrh). By in situ spectrometric measurement the highest values were determined of the area activity of Cs-137 in the location Nová Hůrka (19526 Bq / m2) and the lowest in the location Hadí vrh (5398 Bq / m2). The spectrometric measurements of the soil samples in the laboratory revealed the highest values of the area activity of Cs-137 in the sample from the location Nová Hůrka (10000 Bq / m2) and the lowest values of Cs-137 in the location Hadí vrh (2060 Bq / m2). The contribution of this work is the comparison of in situ spectrometric measurement with the measurement of taken soil samples using the gamma semiconductor spectrometer. The results of this monitoring can provide data on the radiation situation in individual locations in Šumava. By the comparison of the results of the area activity of Cs-137, there has been found a correlation between in situ spectrometric measurements and the laboratory measurements of the soil samples. The results of the area activity of Cs-137 are in an order of magnitude comparable. The differences between the results are probably caused by the measurement conditions.
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An Application of Unmanned Aerial Vehicles in Airborne Radiometry
Dědek, Jiří ; Šálek, Ondřej (advisor) ; Matolín, Milan (referee)
This thesis deals with the use of Unmanned Aerial vehicles (UAV) in radiometric survey. The main goal of this work is to review characteristics of four selected UAV and parameters of employed detectors compared to the classical airborne and ground radiometric survey. Four selected UAV were assessed, hexacopter "Kingfisher" with the detector BGO (Bi4Ge3O12) of the volume 0,2 cm3 , the octocopter "Arducopter" with the 1 cm3 CTZ (CdZnTe) detector, helicopter "Yamaha RMAXG1" with 1,8 l NaI(Tl) detector and airship "ACC15X" with 2,7 l NaI(Tl) detector. Payload capacity, detector sensitivities, flight speed, flight altitude, endurance for one charged battery or full fuel tank and wind resistance were compared among the mini- airborne instruments. The estimation of UAV radiometric data quality was derived from the sensitivity of the detectors, the flight altitude and flight speed. Estimated UAV radiometric data quality was compared to classical airborne and ground typical radiometric data quality. Three selected UAV with a certain altitude and flight speed would achieve a comparable data quality as a classical airborne survey in the altitude of 80 m and flight speed of 50 m/s. Specifically it is hexacopter "Kingfisher" with a scintillation detector D230A at altitude of 40 m and speed of 1m/s, helicopter...
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Modification of Metal Surfaces by Optically Active [7]Helicene Derivatives for Molecular Sensing.
Walaská, Hana ; Kalachyova, Y. ; Elashnikov, R. ; Storch, Jan ; Žádný, Jaroslav ; Lyutakov, O.
New derivatives of 9-(pyridylethynyl)[7]helicenes were firstly prepared and fully characterized in this study. Consequently, they were successfully separated to their (P)- and (M)-enantiomers using a preparative HPLC with chiral stationary phase. These optical antipodes were advantageously used for modification of silver plasmon active nanogratings suitable for a SERS-based detection of (bio)molecules. Properties of such nanostructures were studied using different spectro- and microscopic techniques. As proved by UV-Vis spectrometry, a change of plasmon resonance wavelength position and intensity was observed and indicated the appearance of chiral surface plasmon polarization.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22018110615053 - PDF
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Properties of graphenoid layers
Mach, Radoslav ; Čech, Ondřej (referee) ; Vaněk, Jiří (advisor)
Master thesis “Properties of graphenoid layers” deals with materials of graphenoid nature such as graphene, graphene oxide and its reduced state. The paper effectively summarize basic theoretical knowledge in the first half of its range. In the second half the project deals with practical part consisted of experiments with application of graphene oxide solvents, its analysis and especially comparing properties of non-reduced graphene oxide with its chemically reduced form. Material is examined in a form of applied thin layers on different substrates.
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