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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
581

Komplexní analýza výstražných a obranných látek ploštic vysokoúčinnými separačními metodami / Comprehensive analysis of warning and defense compounds of true bugs by high-performance separation methods

Krajíček, Jan January 2016 (has links)
Insects have developed many strategies of defence against predators in the course of evolution. The evolutionarily oldest and most widely used type of defence is chemical defence, followed by acoustic or optical defence. However, many species of insects use simultaneously multiple types of warning signals, which affect different sensory receptors of the given predator. Such a complex method of warning signals is called multimodal method. It may consist of a combination of simultaneous chemical and optical signals, or a combination of acoustic and optical signalling. The combination of chemical and optical signalling used against a predator is probably the most common form of multimodal signalling. The presented work deals with the analysis of biologically active substances, which participate in the defence mechanisms of a widespread species of insects - true bugs (Heteroptera). Pterin derivatives represent a large group of natural compounds derived from pteridin, bicyclic heterocycle, and they are found in virtually all living organisms from bacteria to vertebrates. In insects, they primarily serve as pigments, resulting for example in striking coloration of cuticles of Heteroptera. The first part of the dissertation was focused on identification and quantification of pterin derivatives in cuticles...
582

Využití kapalinové chromatografie ve farmaceutické analýze a příprava monolitických stacionárních fází pro tenkovrstvou chromatografii / Use of liquid chromatography in pharmaceutical analysis and preparation of monolithic stationary phases for thin-layer chromatography

Vojta, Jiří January 2015 (has links)
(EN) In the first part of this work, analytical methods for determination of impurities of active pharmaceutical ingredients (API) in combined pharmaceutical dosage forms were developed and validated. Development of the methods covered both the optimization of sample preparation procedure and chromatographic conditions. The methods were validated according to International Conference on Harmonization guideline and both of them were confirmed to be able to analyze stability samples. Impurities in paracetamol, codeine phosphate hemihydrate and pitophenone hydrochloride in the presence of fourth API fenpiverinium bromide were separated by using ion-pair reversed phase chromatography with gradient elution. Symmetry C18, 250 x 4,6 mm, 5 µm heated to 35 řC was used as a separation column. A diode array detector was used. The detection wavelengths were set as follows: 220 nm for paracetamol impurity K, 245 nm for paracetamol and its other impurities and 285 nm for codeine, pitophenone and their impurities. Impurities in valsartan, amlodipine besylate and hydrochlorothiazide were separated by reversed phase UHPLC method with gradient elution. Chromatographic column Zorbax Eclipse C8 RRHD, 100 x 3,0 mm, 1,8 µm heated to 30 řC and spectrophotometric detection were used. The detection wavelengths were set as...
583

Využití vysokoúčinných separačních metod pro analýzy biologicky aktivních látek / Analysis of biologically active compounds using high performance separation methods

Adamusová, Hana January 2017 (has links)
In the first part of this doctoral thesis, a new analytical HPLC-MS/MS method for monitoring of concentration changes of 17β-estradiol (βE2) during in vitro mouse sperm capacitation was developed. Capacitation was performed for three initial concentrations of βE2 (200, 20 and 2 μg/L). For all the concentrations a similar trend for the total unbound βE2 was observed. In general, the βE2 concentration decreased to reach its minimum and then increased again. The position of the minimum differed for the individual tested βE2 concentrations. Experimentally obtained results were subjected to the kinetic analysis. The curves fitted through the experimentally determined points displayed an autocatalytic character. For the agreement between the curves obtained by fitting through the experimental points and the theoretical calculated curves, it is necessary to assume that the first step is adsorption of βE2 onto the surface of the sperm controlled by Langmuir isotherm. The kinetic study was also used to study the effects of fluorides and aluminium fluoride complexes on the capacitation of mouse sperm. The experimental points were in very good agreement with the shape of the theoretical curves and this fact verifies the mechanism of the mouse sperm capacitation kinetics. In the second part of this work, two...
584

Charakterizace chirálních a achirálních chromatografických separačních systémů / Chromatograhic characterization of chiral and achiral separation systems

Kučerová, Gabriela January 2018 (has links)
Dissertation thesis is a 5-publications' collection concerning characterization and application potential of cyclodextrins, polysaccharides and macrocyclic antibiotics based chiral stationary phases. The effects of stationary phase and mobile phase are studied. This approach ensures the complex insight into separation systems studied. Systems with different nature of chiral selector were studied by HPLC. Namely, macrocyclic antibiotics and derivatized polysaccharides were used for experiments. Former ones provided better results for enantioseparation of non-coded amino acids than latter ones. Dynamic coating procedure was used for preparation of a new chiral stationary phase. Characterization of new cationic cyclodextrin based chiral stationary phase was performed. Linear free energy relationship method was used for characterization of two different separation systems, i.e. newly prepared stationary phase and commercially available stationary phase. Based on results obtained, newly prepared stationary phase showed better results for separation of different achiral groups of analysts. New stationary phase prepared by dynamic coating was compared with chromatographic system, in which the chiral selector was used as a mobile phase additive. The chiral selector used for the two different approaches was...
585

Využití hmotnostní spektrometrie pro analýzu biologicky aktivních látek / Utilization of mass spectrometry for analysis of biologically active compounds

Kaliba, David January 2018 (has links)
This PhD thesis provides a commented set of four publications. These publications are focused on capillary electrophoresis, liquid chromatography, and UV/Vis spectrometry used to study complexes of rhenium with aromatic ligands. The methods of mass spectrometry with soft ionization techniques, 1 H and 13 C nuclear magnetic resonance, and infrared spectrometry were used for structural characterization of the individual complexes. The complexes were synthetized in reactions of the rhenium precursor tetrabutylammonium tetrachlorooxorhenate with the corresponding ligand under both aerobic and anaerobic conditions. In the course of the research, it was revealed that the prepared complexes (with Re in the oxidation number +V and +VI) are unstable and their oxidation numbers change to another more stable form (Re+VII ). Sub-projects which were successfully implemented during the research were as follows:  Design and successful realization of the process of synthesis of selected rhenium complexes with aromatic ligands 1,2-dihydroxybenzene, 1,2,3-trihydroxybenzene, and 2,3-dihydroxynaphthalene in reactions with and without air access, and their structural characterization by ESI-MS, APPI- MS, LDI-MS, ESI-MS/MS, NMR, and IR.  ESI-MS SRM and UV/Vis time studies of the behaviour of primary rhenium complexes...
586

Stanovení léčiv pomocí HPLC s různými typy detektorů / Determination of drugs by HPLC with different detectors

Benešová, Markéta January 2011 (has links)
This diploma thesis deals with the determination of macrolide antibiotics in wastewater, especially with erythromycin, clarithromycin and roxithromycin. In this time are these pharmaceuticals prescribed quite frequently. Solid phase extraction (SPE) was used for the isolation and the purification of selected analytes from an aqueous matrix; as the suitable procedure was found the using Oasis HLB cartridges. High performance liquid chromatography with mass spectrometry detection (HPLC-MS) was optimized for its analysis of selected pharmaceuticals. The optimized method was used for the determination of pharmaceuticals in real water samples, which was taken at the inflow and the outflow of the urban wastewater treatment plant in Brno-Modřice.
587

Hodnocení zátěže životního prostředí perfluorovanými sloučeninami / Evaluation of environmental load by perfluorinated compounds

Šima, Aleš January 2011 (has links)
The most important substances of the group of perfluorinated compounds are perfluorooctyl sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorooctane sulphonamide (FOSA). Perfluorinated compounds have special physical and chemical properties, which make them valuable for usage in different industrial branches. These properties, which make them so useful are also the reason, why they are so harmful for the environment. The target of theoretical part of the diploma thesis was processing of literature searche on the topic: Evaluation of environmental load by perfluorinated compounds. In the experimental part was developed and optimized a method that was used for the identification and quantification of selected pollutants contained in real soil samples.
588

Stanovení přítomnosti inhibitorů fosfodiesterázy v komunálních odpadních vodách / Determination of the presence of phosphodiesterase inhibitors in municipal wastewater

Smutná, Michaela January 2014 (has links)
This diploma thesis is focused on the determination of phosphodiesterase 5 selective inhibitors in communal waste waters. In this study phosphodiesterase inhibitors levels in municipal waste waters from sewage treatment plants with different numbers of equivalent inhabitants were analyzed. Namely it was sewage treatment plants in Brno – Modřice, Luhačovice and Hodonín. In each of the above mentioned facilities 24 - hour cumulated samples of the influent and effluent waste water were collected. On the Brno - Modřice sewage treatment plant also weekly monitoring of the concentration of phosphodiesterase inhibitors was realized.
589

Organic residue analysis of Red Lustrous Wheelmade Ware vessels traded across the eastern Mediterranean during the Late Bronze Age

Steele, Valerie J. January 2008 (has links)
Red Lustrous Wheelmade Ware (RLWm ware) transport and storage vessels have been excavated from Late Bronze Age (LBA) sites across the eastern Mediterranean. These distinctive vessels were traded for the valuable commodity they contained so far unidentified. Seventy-three sherds (61 RLWm ware, 12 in local fabrics) and two visible residues were analysed for organic residues using standard lipid extraction techniques. Seven residues from a previous study were re-examined. Gas chromatography-mass spectrometry identified four materials ¿ beeswax, bitumen, fat/oil and resin. Beeswax, found only in vessels from Hittite sites in Turkey, was probably used as a post-firing treatment. Fat/oil, present in some sherds from every site, represents the contents of the vessels and showed many of the characteristics of degraded plant oil. Two examples contained a plant sterol and three yielded ricinoleic acid, a biomarker for castor oil. Gas-chromatography compound-specific isotope ratio mass spectrometry of selected residues excluded dairy products, ruminant animal fats and fish oils as source materials for the fats/oils, while comparison with a small database of modern oils created during this study does not exclude plant oils. Selected samples analysed by high performance liquid chromatography-tandem mass spectrometry did not reveal wine residues. Data on the elemental composition of the fabric collected during another study was re-analysed and compared with data from a further published study, confirming the remarkable consistency of RLWm ware fabric. Volume calculations were also attempted to give an estimate of the capacity of the main vessel forms. / Arts and Humanities Research Council / Extensive folders of data and appendices which accompany this thesis are not presently available online.
590

Positron Emission Tomography Imaging of Hepatocellular Carcinoma with Radiolabeled Choline

Kuang, Yu 03 April 2009 (has links)
No description available.

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