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Biocrystallization as a new concept in development of piezoelectronics for use in biomaterials
Dobešová, Kateřina ; Plichta, Tomáš (referee) ; Sedláček, Petr (advisor)
This thesis focuses on biofilament methods and biocrystallization of bacterial cells producing polyhydroxyalkanoates, specifically the bacterium Cupriavidus necator H16. The main techniques used for cell orientation include spin-coating and acoustic waves. Biocrystallization was induced by temperature, osmotic, and acid stress. The degree of cell orientation was monitored by an atomic force microscope, and crystallization was determined by FTIR. Among other parameters, the thickness of the layers was evaluated using a profilometer. The amount of PHA in the bacterial cells was determined by gas chromatography. The preparation of crystalline ordered layers of biomaterials represents a route to piezoelectric biomaterials.
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Involvement of vibrational spectroscopy in the in-situ analysis of PHA in bacterial biomass.
Kevélyová, Barbora ; Samek, Ota (referee) ; Sedláček, Petr (advisor)
The aim of this thesis was the study of polyhydroxyalkanoates in bacterial biomass using the ATR-FTIR method. Furthermore, the PCA method was chosen to evaluate the measured data and observe correlations or differences among the spectra of various biomass samples. The bacterial producents were Aneurinibacillus thermoaerophilus H1, AH30 and AFn2, Cupriavidus malaysiensis DSM 25816, DSM 19416 and DSM 19379 and three strains of Schlegelella thermodepolymerans M 15344, DSM 15264 and LMG 21645. Various heteropolymers with different monomer content and total PHA content were investigated. The monomers in the samples were 3-hydroxybutyrate, 4-hydroxybutyrate, 3-hydroxyvalerate, 4-hydroxyvalerate, 5-hydroxyvalerate and 4-hydroxyhexanoate. As the reference method for accurate quantitative and qualitative determination of polyhydroxyalkanoates in the samples, gas chromatography was performed. The spectra obtained by the FTIR method were compared and significant peaks related to the qualitative properties of PHA, namely monomer composition and crystallinity, were searched for. The PCA statistical method was successfully applied to the collected data from FTIR, with the help of which the qualitative differences between the samples were monitored. The most significant differences were observed in the presence of monomers 4-hydroxybutyrate and 4-hydroxyhexanoate, and they were related to the crystallinity of the samples. The analysis did not show potential for semi-quantitative determination of PHA in biomass. Differences between microorganisms were not observed. The procedure for evaluating FTIR spectra using PCA could in the future be used in the study of biomass containing various monomeric units, especially hydroxyvalerates in case of their higher content within the sample.
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The influence of admixtures on the hydration of Calcium Aluminate phases
Skalík, Martin ; Másilko, Jiří (referee) ; Koplík, Jan (advisor)
This thesis focuses on the effect of admixtures on the hydration time and on the formation of hydration products of calcium aluminate cement and its phases. Three main calcium aluminate phases, CA, CA2 and C12A7, were prepared to study using a high temperature sintering method that was optimised to be as fast as possible. The admixtures used were LiCl, NaCl, sodium tetraborate and citric acid. Prior to the actual hydration, the optimization of the admixture dosage was performed by Vicat test on two commercial aluminate cements, Secar 71 and Secar 80. The hydration with the right amnout of admixtures was monitored by heat flow calorimetry. Hydration products were investigated by X-ray diffraction analysis, Fourier transform infrared spectroscopy and electron microscopy.
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Preparation and characterization of lignin modified by laccase enzyme
Hrušková, Lucie ; Obruča, Stanislav (referee) ; Kalina, Michal (advisor)
This master’s thesis focuses on the enzymatic modification of commercially available lignin using laccase enzyme and monitoring its impact on selected physical and chemical properties. Lignin is an attractive material for the production of renewable chemicals, materials, and energy, but its complex chemical structure poses a major obstacle to its effective utilization. Enzymatic modification appears to be a promising solution for its processing. Experiments were conducted under various conditions, such as pH, enzyme dosage, and reaction time. In the subsequent part of the experiment, the modified lignins were characterized and their results compared with those of the raw kraft lignin before modification. Molecular weight was determined using SEC-MALS, and the concentration of phenolic groups and antioxidant activity were measured. Structural changes were also monitored using FTIR. The results indicate that the enzymatic modification of lignin using laccase led to an increase in the molecular weight of the modified lignins, along with a decrease in the content of phenolic groups and a reduction in antioxidant activity. Based on the obtained results, it can be concluded that the action of the laccase enzyme resulted in lignin polymerization and the formation of new chemical bonds, leading to further aggregation.
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Study of the interaction of hazardous metal – microplastic
Sinčáková, Lenka ; Řezáčová, Veronika (referee) ; Doležalová Weissmannová, Helena (advisor)
Mikroplasty, široko zastúpené vo vodnom prostredí, slúžia ako vektor širokej škály kontaminantov, vrátane ťažkých kovov. Táto práca sa zaoberá adsorpciou piatich ťažkých kovov (Pb, Hg, Zn, Cu and Cd) na polyetylén tereftalát (PET), rozšírený polutant riek a morí. Pokiaľ ide o vplyv veľkosti mikroplastov na proces adsorpcie, nebol zistený jasný trend. Salinita prostredia má značný vplyv na adsorpčný proces s pozorovateľným poklesom adsorbovaných množstiev v prostredí s vysokou iónovou silou. Analyzované ťažké kovy boli zoradené vzostupne podľa ich schopnosti adsorpcie na PET nasledovne: Hg
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FTIR and NIR applications for soil analysis
Mešková, Michala ; Kučerík, Jiří (referee) ; Doležalová Weissmannová, Helena (advisor)
This diploma thesis focuses on the use of infrared spectrometry methods for the analysis of soil samples. The aim of this work was to compare and analyze the soil using the ATR (Attenuated Total Reflectance) and DRIFTS (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) methods and to evaluate the effectiveness of these methods for soil analysis. The results showed that the ATR method is not sufficiently effective and the DRIFT method was used for soil analysis, which proved to be more suitable for the analysis of soil samples.
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Characterization of PVDF material in nanoscale resolution
Pisarenko, Tatiana ; Dallaev, Rashid (referee) ; Sobola, Dinara (advisor)
Tato práce se zabývá charakterizací nanovláken na bázi polyvinylidenfluoridu. Zaměření práce je na piezoelektrické vlastnosti vlákna, které jsou studovány metodou piezoelektrické silové mikroskopie. Takto byly měřeny dva typy odlišných vzorků, které se lišily v parametrech výroby. Odlišnosti vláken v jejich fázovém složení byly také zkoumány za využití Ramanovy spektroskopie a infračervené spektroskopie s Fourierovou transformací. Chemická analýza povrchu a jeho stavu proběhla pomocí rentgenové fotoelektronové spektroskopie. Různé uspořádání nanovláken spolu s jejich průřezem bylo pozorováno rastrovacím elektronovým mikroskopem za využití fokusovaného iontového svazku. Rovněž byla zkoumána smáčivost a kontaktní úhel povrchu vzorků s demineralizovanou vodou. Bylo zjištěno, že vyšší rychlost otáček válce během procesu elektrostatického zvlákňování má velmi významný vliv na jejich uspořádání a tím i na parametry ovlivňující tvorbu piezoelektrického jevu a dalších materiálových vlastností.
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Electrospun fibers based on PVDF and nylon
Černohorský, Petr ; Sobola, Dinara (referee) ; Papež, Nikola (advisor)
Polymer nanofibers used for the construction of triboelectric nanogenerator (TENG) and piezoelectric nanogenerator (PENG) are new and promising technologies for energy recovery. Thanks to the generation of electrical energy based on mechanical movement (deformation), these fibers can find application in the field of self-powered electronic devices. In this work, three nanofibrous structures of materials were prepared by electrostatic spinning: pure polyvinylidene fluoride (PVDF), pure polyamide-6 (PA6) and their mixed combination PVDF / PA6. Non-destructive analyzes such as Raman spectroscopy, FTIR, XPS and electron microscopy were used to study the properties of nanofibers. Analyzes confirmed the positive effect of electrostatic spinning of polymers on the support of the formation of highly polar crystalline -phase in PVDF and , -phase in PA6. The structure arrangement of the nanofibrous material and their defects were observed by scanning electron microscopy (SEM). Furthermore, the contact angle of the wettability of the liquid on the surface was measured for the materials, and the permittivity was measured to monitor the dielectric properties. The described results make the mixed material PVDF / PA6 very promising for further research in the field of nanogenerators and functional textiles.
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Fabrication and characterization of plasmonic nanostructures
Bačo, Ondřej ; Kvapil, Michal (referee) ; Dvořák, Petr (advisor)
This bachelor thesis deals with fabrication and characterization of plasmonic nanostructures. Graphene on a doped silicon substrate with a 285 nm thick layer of silicon dioxide was used for fabrication of these structures. Graphene ribbons with width in the order of hundreds of nanometers were prepared using electron beam lithography (EBL) and reactive ion etching (RIE). Steps in fabrication process were monitored utilizing optical and atomic force microscopy (AFM). Prepared graphene nanostructures were characterized with scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR).
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