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Identification of AC induction motor parameters
Křížek, Tomáš ; Václavek, Pavel (referee) ; Blaha, Petr (advisor)
This thesis describes and realizes (in program Matlab/Simulink and in the microcontroller Freescale 56F8346) one off-line identification method of AC Induction motor parameters which are necessary to implement the field-oriented control strategy. The identification metod identify leakage inductance, magnetizing inductance and secondary time constants. The presented method is evaluted, advantages and disadvantages of this method are evaluated with reference to their possible use in real-machine. The experimental results and schemes which are presented demonstrate the feasibility methods. The thesis is dividend in seven chapters. Second chapter describes the basic principle and model AC induction motor. Third chapter generally describes identification methods. Fourth, fifth and sixth chapters deal with method which is based on a previous work of the authors [4] and [5].
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Detailed characterization of macrocyclic glycopeptide-based chiral stationary phases in SFC
Folprechtová, Denisa ; Kalíková, Květa (advisor) ; Křížek, Tomáš (referee) ; Kohout, Michal (referee)
The choice of a suitable chiral stationary phase is a key factor for successful enantioseparation in chromatographic methods. Macrocyclic glycopeptides are chiral selectors that, due to their unique structure, allow to interact with the analyte by various types of interactions simultaneously, which contributes to their complex retention and enantiodiscrimination mechanisms. Macrocyclic glycopeptides are widely used chiral stationary phases in liquid chromatography, but they have not been thoroughly tested in sub/supercritical fluid chromatography, which currently rank among important separation techniques in terms of chiral analyses. Therefore, the aim of this thesis is a detailed characterization of the enantiodiscrimination and retention mechanisms of macrocyclic glycopeptide-based chiral stationary phases packed with core-shell particles, namely TeicoShell, VancoShell, and NicoShell columns in sub/supercritical fluid chromatography. First, the effect of the mobile phase composition, especially the type and amount of organic modifiers and additives, on individual chromatographic parameters, i.e., retention, resolution of enantiomers, and peak shapes was studied in detail using selected sets of structurally different biologically active chiral compounds and materials. Based on the obtained...
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On-line derivatization of saccharides in capillary electrophoresis
Mareš, Vít ; Křížek, Tomáš (advisor) ; Coufal, Pavel (referee)
Saccharides chains may suffer from various inaccuracies during their biosy- thesis, that effects their biologic functions. Therefore, they can be used for dia- gnosis of some diseases or quality control in biopharmaceutics. Capillary electro- phoresis has its place in diagnosing these occuring errors. In this thesis a method of on-line derivatization of saccharides in fused-silica capillary with 50 cm in lenght and 50 µm in inner diameter was developed. Gluco- se was used as a model molecule, which was labeled by a fluorescent derivatization reagent, 7-aminonaphthalene-1,3-disulfonic acid. Derivatization of glucose and its separation needed optimalization. First was determined an electrophoretic mo- bility of the derivatization reagent in 0.5; 1.0 and 2.5M acetic acid and 20mM phosphate buffer (pH = 3.5). Both, 2.5M acetic acid and 20mM phosphate buffer, were tested as solvents for 7-aminonaphthalene-1,3-disulfonic acid. The reaction with glucose was the best in acetic acid solution. On the contrary, phosphate buf- fer was found to be the best background electrolyte for the separation. Derivatized glucose was detected by UV detector at 229 nm. Henceforth, the reaction con- ditions were adjusted such as reaction time, voltage and time of its application. Input voltage was applied negative due to the...
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Determination of glutathion in plant samples using capillary electrophoresis
Skála, Michael ; Křížek, Tomáš (advisor) ; Kubíčková, Anna (referee)
This work is based on a previously published method for determination of both glutathione forms by capillary zone electrophoresis equipped with UV spectrometric detector. Theoretical part described biological and biochemical functions of glutathione as a molecule. It mentioned historically used methods for glutathione determination, their accuracy, precision and reliability and focused on electrophoretic methods, especially capillary zone electrophoresis. Basic principles of capillary zone electrophoresis were described, followed by an overview of approaches to treatment of different types of samples, with special focus on plant samples. At the end, method this work was based on was described. The experimental part describes the development and optimization of this method. Firstly, optimum chemical composition and ionic strength of background electrolyte were determined - two electrolytes were compared, with NaCl and without NaCl - no significant differences were observed, so NaCl was excluded from BGE. Next, optimum concentration of hexadimethrine bromide was determined. The effect of HDB concentration on electroosmotic flow was investigated. Calibration curve for different concentrations of analytes in water was constructed and repeatability, LOD and LOQ of the method were determined....
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Determination of bitrex using ultra-high performance liquid chromatography
Fuková, Kateřina ; Kubíčková, Anna (advisor) ; Křížek, Tomáš (referee)
In this work, a method for the determination of bitrex (denatonium benzoate) using ultra- high performance liquid chromatography was developed. A Kinetex C18 column (Phenomenex) with dimensions of 100×2.1 mm and a particle size of 1.7 μm was used for the determination. A mixture of acetonitrile with 0.1% formic acid (component A) and deionized water with 0.1% formic acid (component B) was used as the mobile phase. The best separation was achieved with the gradient program set: 0-2 min: 20 % → 70 % A (vol. %); 2- 3 min: 70 % A (vol. %); 3-3,5 min: 70 % → 20 % A (vol. %); 3,5-5 min: 20 % A (vol. %). The temperature of the column during the separation was 40 řC and flow rate was 0,3 ml/min. The developed method was partially validated. Repeatability was measured, the linearity of the method was verified for sample injection 1 μl and 5μl. For the same sample injection limit of detection and limit of quantification was determined. Using the developed method, seven real samples containing bitrex were measured. These samples differed in matrix. The samples were five different coolants, glass cleaner and a washing gel for black clothing. In coolant Carline Antifreeze G13 (producer OMA CZ) the concentration of bitrex was set at 23,4 ppm. In coolant CS Antifreeze G 13 (producer CLASSIC Oil) the concentration...
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Modification of inner capillary surface for electrophoretic separations of liposomes
Píplová, Renata ; Křížek, Tomáš (advisor) ; Čokrtová, Kateřina (referee)
Electroosmotic flow is one of the main factors that affect the resolution of separations in capillary electrophoresis and its modification is often necessary. One way of modification of the electroosmotic flow is the use of dynamic or permanent coating of the inner capillary surface. Such modifications during liposome separation can also reduce the tendency of liposomes to adsorb to the capillary surface. The aim of this work was to find a stable coating that will sufficiently eliminate the electroosmotic flow and to test its effect on the separation of liposomes. At first, the dynamic coatings of the capillary with Pluronic F-127, polyvinylpyrrolidone K30, polydiallyldimethylammonium chloride, polyethylene glycol and polyvinyl alcohol were tested using four different methods. Individual polymers and methods differed in the rate of elimination of the electroosmotic flow as well as in the stability of the capillary coatings. Dynamic coatings with Pluronic F-127, polyvinylpyrrolidone K30 and polydiallyldimethylammonium chloride were selected for further liposome separation testing. Fluorescently labeled liposomes were separated using capillary electrophoresis with laser-induced fluorescence detection and the mobilities of liposomes separated using capillaries with different coatings were determined....
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Chemical modification of glycopeptides and prediction of their retention on hydrophilic liquid chromatography
Pála, Anastasie ; Ječmen, Tomáš (advisor) ; Křížek, Tomáš (referee)
5 Abstract Glycoproteins are an integral part of many cellular processes, without which the complex life of higher organisms wouldn't be possible. Glycoproteins are also important from clinical perspective, since changes of physiological state caused by diseases lead to changes in protein glycosylation. Changes in the abundance of glycosylations or structures of synthesised glycans are associated with diseases such as Alzheimer's disease or cancer and as such can be used as biomarkers for diagnostic purposes. There are several approaches used in the study of glycoproteins, one of which is glycopeptide analysis of enzymatically cleaved glycoproteins. This approach allows analysis of glycoproteins even in complex matrices such as biological samples, as the glycan residues are still connected to their glycosylation sites. This makes the identification of glycoproteins along with their associated glycan structures possible, which oftentimes isn't possible with other analytical approaches. Glycopeptide analysis readily uses high performance liquid chromatography coupled with mass spectrometry. Hydrophilic interaction chromatography is often chosen as the separation mode for glycoproteomic studies, due to its ability to separate glycopeptides with different glycans attached. This chromatographic mode was used in...
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Effect of elution solution on the enrichment and purification of glycopeptides using SPE-HILIC
Chobotová, Michaela ; Kozlík, Petr (advisor) ; Křížek, Tomáš (referee)
Changes in protein glycosylation are related to various diseases such as cancer or Alzheimer's disease. Unfortunately, the analysis of glycoproteins remains a difficult task due to the low proportion of glycopeptides compared to peptides obtained after glycoprotein cleavage. As a result, it is almost impossible to analyze glycopeptides without specific enrichment steps. A suitable method for the enrichment of glycopeptides is solid phase extraction (SPE) using the principle of hydrophilic interaction liquid chromatography (HILIC). Since the choice of solvent significantly affects the enrichment of glycopeptides, the aim of this thesis was to compare the effect of different solvents on the efficiency of glycopeptide extraction using SPE-HILIC. The extraction was carried out on a silica column modified with aminopropyl groups. Model analytes were glycopeptides obtained by tryptic digestion of human IgG. During the comparsion of acetonitrile, methanol and isopropanol, acetonitrile was chosen as a suitable elution solvent. During the conditioning and washing step, the content of acetonitrile was changed (65%, 75% and 85%), whereby the elution of glycopeptides is accelerated as the amount of acetonitrile decreases. In the elution step, the effectiveness of different acetonitrile contents (5%, 10% and...
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Production and characterization of novel aryl sulfotransferases and their use in bioanalytics
Petránková, Barbora ; Bojarová, Pavla (advisor) ; Křížek, Tomáš (referee)
Polyphenols are the most common natural substances found in food. The largest group is represented by flavonoids, phenolic acids and catechols. Polyphenols are metabolized in the body during the biotransformation phase II, they can be sulfated, glucuronylated or methylated. To study biotransformation, it is necessary to have defined standards. Sulfated polyphenols can be prepared by enzymatic sulfation, which needs much milder reaction conditions compared to chemical sulfation. Prokaryotic sulfotransferases use 3'-phosphoadenosine-5'-phosphosulfate (PAPS) as a sulfate donor for sulfation, which is very expensive and difficult to regenerate. An alternative is the group of bacterial aryl sulfotransferases (EC 2.8.2.22), which catalyze the transfer of a sulfate group from a phenolic donor to a phenolic acceptor. Two bacterial aryl sulfotransferases from Desulfitobacterium hafniense and Escherichia coli have been described in the literature so far. The present thesis deals with the production, purification and biochemical characterization of two new bacterial aryl-sulfotransferases from Desulfosporosinus sp. HMP52 and Salmonella bongori. The enzymes were heterologously expressed in E. coli and purified by affinity chromatography. Their pH and temperature optimum, stability in organic solvents and...
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Extension of artificial intelligence DeepReI and its application in practice
Hurychová, Nikola ; Sobotníková, Jana (advisor) ; Křížek, Tomáš (referee)
Diploma thesis deals with expanding the artificial intelligence DeepReI with the prediction of retention indices of substances in gas chromatography for standard non-polar and polar stationary phases. The theoretical part describes artificial intelligence, convolutional neural networks, and the principles of neural network learning. There is also a brief overview of the applications of neural networks in analytical chemistry. In the experimental part, the original DeepReI model was extended to predict the retention indices of substances for standard non-polar and polar stationary phases. Furthermore, more accurate predictions of retention indices were achieved for semi-standard non-polar stationary phases compared to existing models. The applicability of the model for substance identification was verified through non-targeted analysis of non-alcoholic beers using gas chromatography with mass detection.
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