|
|
Effect of controlled degradation on the structure of high-impact polypropylene
Pragerová, Barbora ; Kratochvíla,, Jan (referee) ; CSc, Zdeněk Buráň, (advisor)
This thesis deals with the effect of controlled degradation on the structure of ethylene-propylene copolymers. The studied samples were produced in reactor as a heterophase mixture of homopolymer PP and~E/P copolymer on Ziegler-Natta catalysts. Two samples were degraded to a higher melt flow index using peroxides. These materials were then compared with reactor-prepared samples of the same melt flow index. In total, six samples of E/P copolymers were investigated, i.e. two series of three comparison samples each. For all samples, the melt flow index and the soluble fraction in xylene were determined (using the standard method according to XS-ISO 16152 and also XS-FIPA). Furthermore, in order to obtain detailed information about the structure of these materials, the granular samples were first subjected to TREF (Temperature rising elution fractionation. Each sample was separated into three fractions for which the molecular weight distribution was then determined by gel permeation chromatography (GPC). Nuclear magnetic resonance C13 NMR provided additional information. Changes in the structure of the E/P copolymers after controlled degradation were evaluated, and these degraded materials were also compared with their reactor equivalents produced directly with a higher melt flow index.
|
|
|
Utilization of Diffusive Techniques in Study on Reactivity of Biocolloids
Kalina, Michal ; Maršálek, Roman (referee) ; Mráček, Aleš (referee) ; Klučáková, Martina (advisor)
The main aim of this thesis is the utilization of simple diffusion techniques for the study on transport properties of copper ions in the systems containing humic acids with respect to the other parameters, which can affect the process (the structure of diffusion environment, the interactions between transported specie and diffusion matrices, selective blocking of binding sites of humic acids). The first part of experimental works was focused on characterization of studied materials (humic acids, humic sol and humic hydrogel). The main part of the thesis was dealing with the optimization of simple diffusion techniques, which were suitable for the study on transport of copper ions in matrices containing humic acids, taking into account the mutual interactions between studied components in the system. The obtained diffusion characteristics were compared to the data determined using sorption experiments. Consequently, the minor goal of the experimental works of this thesis was also the assessment of the influence of basic physico-chemical parameters of studied materials on transport phenomenon.
|
|
|
Fractionation and molecular organization of humic acids
Chytilová, Aneta ; Enev, Vojtěch (referee) ; Klučáková, Martina (advisor)
Humic acids are part of the natural organic matter occurring all around us. The aim of this thesis is to study the molecular organization, conformation of humic acids in aqueous solutions, that always raise a number of questions. For a long time, the scientists all over the world argue, if humic acid are polymers, micelles or supramolecules. Over time, thanks to new technologies, their opinions are moving away from a polymer model and tend rather to supramolecular arrangement of humic acids. Studying humic complex systems is not easy, because they are polydisperse and heterogeneous, which significantly complicates any characterization. Moreover, its molecular organization is affected by many factors such as e.g. pH, ionic strength and etc. For the study of the conformation of humic acids, concentration series of IHSS (International humic substances asociation) Leonardite humic acids stamdards in four different mediums were prepared: 0,1 M NaOH, humic acids in water with pH modified to 12 (basic medium), 0,1 M NaOH + 0,1 M HCl, 0,1 M NaCl (neutral environment). Furthermore it has been performed the fractionation of humic acids for the purpose of simplifying the complicated structure. Prepared concentration series were characterized with several analytical methods such as ultraviolet and visible spectroscopy, dynamic light scattering, electrophoretic light scattering, microrheology, gel permeation chromatography, potentiometric pH determination and direct conductometry. Diploma thesis is built on the previous bachelor thesis in which different sample of humic acids was studied. The measured results indicate that the studied systems show supramolecular behavior and in some cases are subject to aggregation into larger units (micelles).
|
|
|
Qualitative analysis of selected glycosphingolipids subclasses isolated from human blood plasma using HILIC-ESI-MS/MS
ŠIKLOVÁ, Michaela
This bachelor thesis deals with the qualitative analysis of selected subclasses of glycosphingolipids isolated from human blood plasma using hydrophilic interaction liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HILIC-ESI-MS/MS). Glycosphingolipids are ubiquitous and structurally very diverse components of cell membranes involved in many cellular functions. It has been shown that changes in the structures of glycosphingolipids and their distinct expression can pose a key factor in the development of numerous diseases and different types of cancer.The theoretical part of this thesis is dedicated to a summary of fundamental knowledge about glycosphingolipids, their biosynthesis, classification, biological functions and their association with various types of diseases and cancers. Furthermore, methods of isolation, purification and analytical possibilities for the determination of glycosphingolipids in biological samples are described here.In the experimental part, blood samples were taken and processed together with the preparation of the necessary solutions, plasma samples, and standards. Moreover, a test analysis, optimization of mobile phase gradient and comparison of the most frequently used extraction methods according to Folch, Bligh and Dyer, Matyash, and Alshehry alongside fractionation of lipid extract is described in this part. An integral part of the experimental section was the identification and structural characterization of glycosphingolipids within selected subclasses, including the generation of GSL profiles in human blood plasma. In conclusion, the results of the work and answers to the stated research questions are summarized, including the evaluation of possible improvements in this field.
|
|
|
Solubility analysis of lignocellulosic substances with antioxidative efficiency
Hrušková, Lucie ; Kalina, Michal (referee) ; Kovalčík, Adriána (advisor)
One of the main obstacles to efficiently valorise lignin is its heterogeneous solubility, which varies depending on the biological origin and the method of isolation. The theoretical part of the bachelor thesis is devoted to a basic description of lignin from its structure to its specific properties, which has led to a wide range of studies on lignin. The experimental part of the thesis deals with the determination of the solubility of commercially available lignin in selected organic solvents Solubility was determined in a total of 15 pure or mixed solvents. The highest solubility of lignin was achieved in water, in which a solubility of 99.16 % was measured. For the eight best solvents, the size and stability of the dissolved particles were further analyzed. It was found that nanoparticles can be prepared using water and DMSO. Further, the antioxidant activity (expressed by TEAC parameter) and its structure (by FTIR) were determined for the dissolved lignin and its change was recorded. Based on the solubility results, two and three step fractionations were performed. Size, stability, and antioxidant activity were determined for the final fractions. The results obtained showed that during each fractionation step, characteristic functional groups were removed, thus decreasing the antioxidant activity of the resulting fractions.
|
|
|
Effect of controlled degradation on the structure of high-impact polypropylene
Pragerová, Barbora ; Kratochvíla,, Jan (referee) ; CSc, Zdeněk Buráň, (advisor)
This thesis deals with the effect of controlled degradation on the structure of ethylene-propylene copolymers. The studied samples were produced in reactor as a heterophase mixture of homopolymer PP and~E/P copolymer on Ziegler-Natta catalysts. Two samples were degraded to a higher melt flow index using peroxides. These materials were then compared with reactor-prepared samples of the same melt flow index. In total, six samples of E/P copolymers were investigated, i.e. two series of three comparison samples each. For all samples, the melt flow index and the soluble fraction in xylene were determined (using the standard method according to XS-ISO 16152 and also XS-FIPA). Furthermore, in order to obtain detailed information about the structure of these materials, the granular samples were first subjected to TREF (Temperature rising elution fractionation. Each sample was separated into three fractions for which the molecular weight distribution was then determined by gel permeation chromatography (GPC). Nuclear magnetic resonance C13 NMR provided additional information. Changes in the structure of the E/P copolymers after controlled degradation were evaluated, and these degraded materials were also compared with their reactor equivalents produced directly with a higher melt flow index.
|
|
|
Use of thin layer chromatography for fractionation of humic substances isolated from oxyhumolite
Hegrová, Nela ; Doskočil, Leoš (referee) ; Enev, Vojtěch (advisor)
The main goal of this thesis was to optimize the fractionation of humic substances (HS) using the method of Thin-layer chromatography, so that it can be used for physico-chemical characterization of the obtained individual organic fractions. Due to the high content of HS in the natural oxyhumolite matrix this oxidized brown coal was selected as a source of these biocolloid compounds which were isolated according to the international IHSS procedure. The sample of native oxyhumolite and oxyhumolite after extraction was characterized by thermal techniques such as thermogravimetric (TGA) and elemental analysis (EA). The above-mentioned oxyhumolite samples were further analyzed by Fourier transform infrared spectroscopy, mainly for deeper understanding of their structure in terms of an organic matrix containing HS. Characterization of isolated HSs was performed by the following thermochemical and spectrometric techniques, elemental analysis, thermogravimetry, ultraviolet and visible electromagnetic absorption (UV/Vis) molecular spectroscopy, Fourier transform infrared spectroscopy and steady-state fluorescence spectroscopy. Molecular absorption spectroscopy (UV/Vis) and steady-state fluorescence spectroscopy were used for physicochemical characterization of individual organic fractions.
|
|
|
Formulation and testing of rifampicin-loaded branched polyesters nanoparticles
Balciarová, Andrea ; Dittrich, Milan (advisor) ; Šnejdrová, Eva (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Consultant: doc. RNDr. Milan Dittrich, CSc. Student: Andrea Balciarová Title of Thesis: Formulation and testing of rifampicin-loaded branched polyesters nanoparticles In presented thesis, the main attention in theoretical part is focused on nanoparticles for targeted drug delivery, their types, structure and carriers used for their preparation. Moreover, in this part there is an overview of physicochemical characteristics and preparation methods of polymeric nanoparticles applicable in formulation of pharmaceutical products. The experimental part is concerned on studying the influence of the concentration of biodegradable polymers, the presence of cationic surfactants and rifampicin as model drug substance on nanoparticles΄ size and zeta-potential. The main attention is given to nanoparticles decoration with anionic biopolymers, hyaluronic acid and xanthan gum. The simple method of preparation which is usable in nanosystems formulation that influence biological functions purposefully was tried and tested in different contexts.
|
|
|
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.
|
|
|
Application of thin layer chromatography (TLC) for fractionation of humic substances.
Hegrová, Nela ; Doskočil, Leoš (referee) ; Enev, Vojtěch (advisor)
The main aim of this Bachelor thesis was to suggest and optimize a method of fractionation of organic matter of humic substances using thin-layer chromatography (TLC). HS Pahokee Peat standards have been characterized by thermochemical and spectrometric techniques such as thermogravimetry, elemental analysis, UV-Vis and Fourier-transform infrared spectrometry. Molecular absorption spectrometry in the ultraviolet and visible range of electromagnetic radiation and steady-state fluorescence spectrometry were used for physicochemical characterization of organic fractions. Using fluorescence spectrometry, humic substances were found to be composed of fluorophores of humic and non-humic (protein) character. Organic fractions corresponding to the humic fluorphores were characterized by a higher aromaticity, average molecular weight and higher content of oxygen substituents on the aromatic nucleus. In contrast, the organic fractions corresponding to the protein constitutional units were distinguished by low values of the humification index. These tell us about microbial origin of these organic substances during the genesis of HS Pahokee Peat.
|
guest ::
