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Characterization of new chiral separation systems for HPLC
Vozka, Jiří ; Tesařová, Eva (advisor) ; Sýkora, David (referee) ; Petr, Jan (referee)
The dissertation thesis is focused on the physico-chemical characterization of interaction mechanisms of chiral stationary phases based on derivatized cyclofructans. Correct interpretation of retention and enantiodiscrimination processes substantially facilitates the development and optimization of new enantioselective methods using cyclofructan-based chiral stationary phases. At first, the interaction mechanisms of three commercially available cyclofructan-based stationary phases were studied in normal-phase mode of liquid chromatography. Namely, systems using chiral stationary phases based on dimethylphenyl carbamate cyclofructan 7, R-naphtylethyl carbamate cyclofructan 6 and isopropyl carbamate cyclofructan 6 were studied. Linear free energy relationship model was used as a basic tool for characterization of interactions on the stationary phases. The mentioned model revealed that the main interactions contributing to retention in cyclofructan-based systems are hydrogen bond acidity and dipolarity/polarizibility, while dispersion interactions cause decrease of retention. The impact of oligosaccharide skeleton of the cyclofructan selector on the enantioselectivity was elucidated by the comparison with seemingly analogous cyclodextrin-based chiral stationary phases. Cyclofructan-based chiral...
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Liquid chromatography methods for analysis of microbial secondary metabolites of bioactive nature
Tylová, Tereza ; Olšovská, Jana (advisor) ; Cvačka, Josef (referee) ; Sýkora, David (referee)
(EN) This work is focused on development of new analytical methods involving modern solid phase extraction (SPE) for sample purification and pre-concentration, state-of-art ultra high- performance liquid chromatography (UHPLC) for separation of analytes and detection using diode-array detection (DAD) and/or time-of-flight mass spectrometry (ToFMS). The major part of the results has been published in prestigious international journals. The relevant yet unpublished results are included in the thesis as well. Besides a model comparison of various column chemistries used for "ultra-high performance" separations, some meaningful applications were developed. While one part of applications deal with determination of antibiotics as environmental contaminants that are responsible for the development and spread of microbial resistance, the second part is concerned with analyzing and finding of potential natural source of novel antimicrobial agents that can be further used as new antibiotics. The first part of the thesis was focused on the determination of residual antibiotics in different matrices (liquid hog manure, wastewater, surface water). The mostly prescribed antibiotics in both human and veterinary medicine were chosen as analytes in this study employing analytical methods consisting of UHPLC-DAD and...
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Modern separation and spectrometric techniques for biological sample lipidom investigation
Havelková, Eva ; Bosáková, Zuzana (advisor) ; Sýkora, David (referee)
Modern separation and spectrometric techniques for biological sample lipidom investigation Due recent progress in field of mass spectrometry the lipidomics, part of metabolomics, is increasing its importance for broad fields of biological study. The aim of this study is to test the lipid extraction techniques and to optimize the preseparation and separation of lipids suitable for mass spectrometry detection. The fragmentation patterns of four, the most abundant lipid classes of glycerolipids (PC, PE, TG, DG), were acquired for the proposed system. These patterns were compared with literature. The most appropriate method for extraction was declared technique according Folch based on methanol and chloroform solution. The preseparation due SPE method is very useful tool for lipid determination. The optimized were focused to reach higher recovery especially in polar lipid fraction. Proposed HPLC system is based on methanol with ammonium buffer, water and isopropanol. The testing was done on three columns with different type of sorbents (Gemini, Syncronis and Kinetex). The separation was evaluated according mass spectrometer response, shape and wide of particular analytes peaks. Composition contains 20% of water was determinate as the best and also the best separation was achieved by Kinetex column. The proposed...
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Mass Spectrometry Imaging of Metformin in Tissue Sections
Strnad, Štěpán ; Sýkora, D. ; Vrkoslav, Vladimír ; Cvačka, Josef ; Maletínská, Lenka ; Pirník, Zdenko
Mass spectrometry imaging is a powerful technique suitable for visualization of the distribution of a wide variety of compounds within tissue sections. The main aim of the study was the development and optimization of a sample preparation procedure allowing determination of the distribution of orally dosed metformin in mice kidney sections. Metformin is the first-line medication for the treatment of type 2 diabetes. The optimization of the sample preparation step before imaging experiments included the selection of a suitable matrix and the optimization of various parameters of MALDI analysis. 2,5-dihydroxybenzoic acid was identified as the best matrix providing highest sensitivity. A sublimation method was successfully used for the matrix deposition. The highest relative concentration of metformin was found in the inner zone of kidney 30 minutes after the drug administration.
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Computational modelling of aerodynamic noise of flow past a solid body
Sýkora, Daniel ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
Diploma thesis is focused on computational modelling of aerodynamic noise of flow past a solid body. Computation of flow around a cylinder is performed for different meshes and time steps in initial part of the thesis. Results from every computation are compared. Computation aerodynamic noise due to flow around a cylinder is simulated in other part of diploma thesis. In the second benchmark computation, turbulent models have to be considered, because flow with high Reynolds number is turbulent. Computation is based on two different ways: acoustic analogy and direct method. A few different turbulent models is described and is analyzed influence to modelling aerodynamic noise. The results and knowledge of the benchmarks computation have been used in compu-tational modelling of aerodynamic noise of flow around simplified side view mirror. Surface (2D) and spatial (3D) simulations are performed. Based on computation modelling of aerodynamic noise of flow around simplified side view mirror has been designed new geometry, that aim is reduced aerodynamic noise and improved aerodynamic parameters.
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Modern methods for user authentication
Sýkora, Daniel ; Stančík, Peter (referee) ; Hajný, Jan (advisor)
The main focus of Master’s thesis is modern methods for user authentication. In the first part are briefly described currently used protocols and pointed out thein advantages and disadvantages. The theoretical introduction analyzes the principles of zero-knowledge authentication, password-based protocols and describes the concept of a new generation hash function. The practical part describes the specific implementation of authentication protocols - Ohta-Okamoto protocol as a representative of the zero knowledge protocols and SRP (Secure Remote Password), which represents password-based protocols. In both cases, the installation procedure is described following the analysis of their implementation (at the source code level) and then compared with the transmitted data captured by Wireshark. The SRP protocol is verified by AVISPA tool. There is summary of both protocols security analysis in the conclusion.
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Open-tubular capillary electrochromatography with bare gold nanoparticles-based stationary phase applied to separation of trypsin digested proteins
Mikšík, Ivan ; Lacinová, Kateřina ; Zmatlíková, Zdeňka ; Sedláková, Pavla ; Král, V. ; Sýkora, D. ; Řezanka, P. ; Kašička, Václav
Open-tubular capillary electrochromatography (OT-CEC) using bare gold nanoparticles-based stationary phase has been applied to separation of tryptic peptide fragments of native and glycated proteins, bovine serum albumin and human transferrin. OT-CEC with bare gold nanoparticles stationary phase was found to be a suitable technique for separation of complex peptide mixtures originating from enzymatic (tryptic) digestion of native and glycated bovine serum albumin and human transferrin, and for glycation studies of these proteins.
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Analysis of antimicrobial peptides by capillary electrophoresis
Ehala, Sille ; Niederhafner, Petr ; Čeřovský, Václav ; Řezanka, P. ; Sýkora, D. ; Král, V. ; Kašička, Václav
Capillary electrophoresis was used for the purity degree determination of new antimicrobial peptides: octadecapeptide melectin and tetradecapeptide mastoparan PDD-B, and their synthetic analogues. Besides, four semiempirical models correlating electrophoretic mobilities of these peptides with their charge and size (relative molecular mass) were applied to predict their probable structures in solution. Additionally, capillaries coated with gold nanoparticles were employed for the separation of mixtures of antimicrobial peptides.
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