|
|
Production and characterization of biosurfactants
Kratochvílová, Olga ; Samek, Ota (referee) ; Obruča, Stanislav (advisor)
This diploma thesis deals with the microbial production of biosurfactants of selected bacterial strains. In order to test the biosurfactant production ability, screening methods were chosen to be able to review the potential of the selected strains to produce biosurfactants. With the scope of the work, 11 bacterial strains, which are used as polyhydroxyalkanoate (PHA) producers, have been tested. The ability to produce biosurfactants was tested in all strains both in complex inoculation and mineral production media. The presence of biosurfactants in Pseudomonas putida was detected on the basis of the results obtained after cultivation in inoculation and production media. The bacteria Pseudomonas fulva was put under more deep study to support their production by cultivation in different types of production media supplemented by different sources of carbon and nitrogen, and the effect of cultivation time was tested as well. Biosurfactants produced by these bacteria were subsequently identified by Fourier transform infrared spectroscopy (FTIR) on the basis of which the substances were identified as rhamnolipids. According to thin-layer chromatography result (TLC), Pseudomonas putida produces a mixture of mono- and dirhamnolipids, with monorhamnolipids being more dominant in our samples.
|
|
|
Morphology of Polyamide 12 and Polyamide 11 formed at overpressure and underpressure
Bělašková, Marie ; Tocháček, Jiří (referee) ; Bálková, Radka (advisor)
In this master thesis it was studied morphology of polyamide 12 (PA12), polyamide 11 (PA11) and their blends in the percent ratios 95/5, 75/25, 50/50, 25/75 and 5/95 formed at pressure 7 MPa in a calorimeter both after continual heating and cooling and after annealing and isothermal crystallization. Neat polyamides and blends were further characterized by thermogravimetric analysis, differential scanning calorimetry at atmospheric pressure, Fourier-transform infrared spectroscopy in attenuated total refection, and X-ray diffraction analysis. The increased pressure improved level of polyamide chains ordering in crystal lamellae. Thermal annealing improved especially ordering of PA12, isothermal crystallization led to considerable increase of crystallinity, whereas PA11-rich blends supported perfection of PA12 crystals. Partial transformation of - to -structure occurred in case of neat PA12 at high pressure, the change of the chain conformation into the closer one occurred in neat PA11 without transformation of the type of crystal structure.
|
|
|
Plasticizing of polyhydroxyalkanoates in microbial cells - inspiration for development of artificial controlled release systems
Liczka, Jan ; Obruča, Stanislav (referee) ; Sedláček, Petr (advisor)
The diploma thesis is focused on the study of the mechanism of plasticization of polyhydroxyalkanoates (PHA) in vivo, focusing mainly on methods of isolation native PHA granules and physical and chemical methods of initiation their phase transitions. The literature search prepared in this work deals with this microbial polyester and further focuses on individual methods of isolating PHA from bacterial cells. The main task of the experimental work was to optimize the isolation process of native PHA granules, as well as to design and test processes that initiate the PHA crystallization in isolated granules, as well as analytical procedures to correctly detect this phase transition. Isolation of PHA granules from Cupriavidus necator was performed by enzymes, centrifugation several times and sonication of the cells. Fourier transform infrared spectroscopy (FTIR) and an enzymatic method in which amorphous PHA is selectively degraded by PHA-depolymerase with turbidimetric detection of its loss in dispersion was used to detect PHA crystallization. Techniques based on fluorescence staining of granules (fluorescence spectroscopy and flow cytometry) were used in a more detailed study of the mechanism of PHA plasticization in granules. The results of the analyzes confirmed, among other things, that the optimized procedure makes it possible to isolate granules in the amorphous state, which remain amorphous even after drying and are comparable to native granules in their basic physicochemical properties.
|
|
|
Fabrication and characterisation of plasmonic antennas on selected thin film with aim to get enhanced absorption due to presence of strong coupling
Vodička, Martin ; Kepič, Peter (referee) ; Liška, Jiří (advisor)
Strong coupling systems offer many important applications in various fields such as photonics, chemistry, nonlinear optics and others. This Bachelor's thesis focuses on the fabrication of metal plasmonic structures suitable for the formation of strong coupling between localized surface plasmon antennas and hexagonal boron nitride (hBN) thin film phonons in the infrared region. In the case of inducing a strong coupling, an increase in absorption should occur, which makes it possible to use this system to fabricate an infrared detector, the so-called microbolometer. The thesis summarizes important findings from electromagnetic field theory, describes the formation of strong coupling from the perspective of classical physics and gives examples of systems with strong coupling. Furthermore, the formation of surface plasmon polaritons and localized surface plasmons (LSPs) is theoretically described. Plasmonic antennas, their fabrication, applications and physical properties of hBN are described. In the practical part of the thesis, fabrication of plasmonic antennas under or on hBN thin film has been realized. The fabricated samples were characterized by scanning electron microscopy and the spectral response was measured by Fourier transform infrared spectroscopy. In the spectra, the absorption of hBN at 7.3 m was confirmed and additional transmittance minima corresponding to the presence of antennas were detected. The presence of a strong coupling between the LSPs antennas and the phonons of the native SiO2 layer was probably observed. Whether there was a strong coupling between the LSPs antennas and the hBN phonons cannot be inferred from the the obtained results.
|
|
|
CHARACTERIZATION OF WRAPPAGING FILMS BASED ON POLYETHYLENE AND POLYPROPYLENE
Bělašková, Marie ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
By seven kinds of coextruded and blown packing polyethylene and polypropylene based films, which are supplied by Granitol were characterized in this bachelor thesis. The following methods were used for characterization: thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, confocal laser scanning microscopy , and scanning electron microscopy. The methods made possible to determine the composition of the films and to evaluate the degree of crystallinity.
|
|
|
Study of the interaction of selected pharmaceuticals with microplastics
Ioani, Aldina ; Řezáčová, Veronika (referee) ; Doležalová Weissmannová, Helena (advisor)
The bachelor thesis aims to study the interaction of selected pharmaceuticals from the group of analgesics and antibiotics with microplastics. The analysis was conducted in the mid-infrared region, which is used to identify chemical structure of the substances. Fourier transform infrared spectroscopy was used as an analytical method. The samples were subjected to technique attenuated total reflection. Ibuprofen and trimethoprim were chosen as analytes due to their common usage in the population. Sorption of pharmaceuticals was undergoing on polyhydroxybutyrate, which is a kind of biodegradable plastics and polyethene terephthalate, which is synthetic. Measured results showed that for the study of interaction with pharmaceuticals, it is more suitable to use biodegradable plastic polyhydroxybutyrate than polyethene terephthalate because of its better results. Infrared spectra output is very influenced by a selection of a solvent.
|
|
|
Microplastics in solid matrices of the environment
Pospíchalová, Eliška ; Cajthaml, Tomáš (advisor) ; Innemanová, Petra (referee)
Microplastics, plastic particles of 5 mm-1 nm in size, are now widespread across different ecosystems. The increasing amount of microplastic contamination of aquatic and terrestrial environments requires the development of standardized methods for their separation and analysis. One of the main vectors of microplastic input to terrestrial ecosystems is through sewage sludge. The sludge is recycled for fertilization and reclamation due to its high organic matter content. Scientists have already been able to quantify and identify a range of microplastics in sewage sludge of different sizes, polymer types, shapes, etc. This thesis focuses on the optimization of existing methodologies to extract microplastics from solid environmental samples and their subsequent qualitative and quantitative analysis. The steps required for sample pre-treatment prior to analysis, namely reduction in organic matter content by the Fenton reaction process and density-based separation of microplastics by flotation in saturated NaI solution (1.8 g/cm3 ) using centrifugation, were optimized. Microplastics in size fractions of 20-40 μm and 150-300 μm were fabricated and introduced into flotation and total recovery experiments of the methodology to determine the recovery. Fluorescence microscopy was chosen for quantitative...
|
|
|
Fabrication and characterisation of plasmonic antennas on selected thin film with aim to get enhanced absorption due to presence of strong coupling
Vodička, Martin ; Kepič, Peter (referee) ; Liška, Jiří (advisor)
Strong coupling systems offer many important applications in various fields such as photonics, chemistry, nonlinear optics and others. This Bachelor's thesis focuses on the fabrication of metal plasmonic structures suitable for the formation of strong coupling between localized surface plasmon antennas and hexagonal boron nitride (hBN) thin film phonons in the infrared region. In the case of inducing a strong coupling, an increase in absorption should occur, which makes it possible to use this system to fabricate an infrared detector, the so-called microbolometer. The thesis summarizes important findings from electromagnetic field theory, describes the formation of strong coupling from the perspective of classical physics and gives examples of systems with strong coupling. Furthermore, the formation of surface plasmon polaritons and localized surface plasmons (LSPs) is theoretically described. Plasmonic antennas, their fabrication, applications and physical properties of hBN are described. In the practical part of the thesis, fabrication of plasmonic antennas under or on hBN thin film has been realized. The fabricated samples were characterized by scanning electron microscopy and the spectral response was measured by Fourier transform infrared spectroscopy. In the spectra, the absorption of hBN at 7.3 m was confirmed and additional transmittance minima corresponding to the presence of antennas were detected. The presence of a strong coupling between the LSPs antennas and the phonons of the native SiO2 layer was probably observed. Whether there was a strong coupling between the LSPs antennas and the hBN phonons cannot be inferred from the the obtained results.
|
|
|
Plasticizing of polyhydroxyalkanoates in microbial cells - inspiration for development of artificial controlled release systems
Liczka, Jan ; Obruča, Stanislav (referee) ; Sedláček, Petr (advisor)
The diploma thesis is focused on the study of the mechanism of plasticization of polyhydroxyalkanoates (PHA) in vivo, focusing mainly on methods of isolation native PHA granules and physical and chemical methods of initiation their phase transitions. The literature search prepared in this work deals with this microbial polyester and further focuses on individual methods of isolating PHA from bacterial cells. The main task of the experimental work was to optimize the isolation process of native PHA granules, as well as to design and test processes that initiate the PHA crystallization in isolated granules, as well as analytical procedures to correctly detect this phase transition. Isolation of PHA granules from Cupriavidus necator was performed by enzymes, centrifugation several times and sonication of the cells. Fourier transform infrared spectroscopy (FTIR) and an enzymatic method in which amorphous PHA is selectively degraded by PHA-depolymerase with turbidimetric detection of its loss in dispersion was used to detect PHA crystallization. Techniques based on fluorescence staining of granules (fluorescence spectroscopy and flow cytometry) were used in a more detailed study of the mechanism of PHA plasticization in granules. The results of the analyzes confirmed, among other things, that the optimized procedure makes it possible to isolate granules in the amorphous state, which remain amorphous even after drying and are comparable to native granules in their basic physicochemical properties.
|
|
|
Study of the interaction of selected pharmaceuticals with microplastics
Ioani, Aldina ; Řezáčová, Veronika (referee) ; Doležalová Weissmannová, Helena (advisor)
The bachelor thesis aims to study the interaction of selected pharmaceuticals from the group of analgesics and antibiotics with microplastics. The analysis was conducted in the mid-infrared region, which is used to identify chemical structure of the substances. Fourier transform infrared spectroscopy was used as an analytical method. The samples were subjected to technique attenuated total reflection. Ibuprofen and trimethoprim were chosen as analytes due to their common usage in the population. Sorption of pharmaceuticals was undergoing on polyhydroxybutyrate, which is a kind of biodegradable plastics and polyethene terephthalate, which is synthetic. Measured results showed that for the study of interaction with pharmaceuticals, it is more suitable to use biodegradable plastic polyhydroxybutyrate than polyethene terephthalate because of its better results. Infrared spectra output is very influenced by a selection of a solvent.
|
guest ::
