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Cereals - Active Substances, Biological Effects and Selected Applications in Food Industry
Lichnová, Andrea ; Tremlová, Bohuslava (referee) ; Vávrová, Milada (referee) ; Márová, Ivana (advisor)
The presented doctoral thesis is focused on the study of the biological effects of active compounds found in cereals, on the development of methods of analysis these effects, on the determination of the content of active substances and characterization of the relationship between composition and biological effects of cereals and cereal products. For the analysis several kinds of raw cereal samples (flakes, flour, germ, bran), flavored extruded cereal products and also samples of paddy and husked rice were chosen. To major types of analysed active compounds belong mainly phenolic compounds in the form of glycosides and aglycones, and also saccharides. Group parameters such as total polyphenols, flavonoids and total and reducing saccharides were determined spectrophotometrically, individual phenolics and saccharides were determined by high performance liquid chromatography (HPLC). TEAC, DPPH and CLAMS methods were used to determine the antioxidant activity. Indirect methods of determination of substances with antioxidant effect were used as well. Results of the total antioxidant activity were compared with values of antimutagenic/genotoxic activity obtained by several microbial test systems. Antimutagenic effect was expressed as a percentage of inhibition of effect of standard mutagen and could be considered as a potential preventive effect of cereals to DNA arising primarily by free radicals effect. The highest values of group and individual phenolics, antioxidant and antimutagenic activity were found in germs, bran, in buckwheat products and in coloured and raw rice. In flavoured cereal products addition of chocolate or fruit positively influences content of active phenolic substances as well as sugars, antixidant and antimutagenic activity. In a representative sample of Czech population, questionnairy study was performed to monitor interest in cereals and consumer preferences. The most of consumers consider cereals with chocolate flavour as less healthy than confirmed results of laboratory analyses. In this study some new food products were developed. Several types of model cereal products containing plant (fruit, vegetables) extracts were proposed. Extracts were added to cereals in freeze-dried and encapsulated form. The highest positive effect exhibited addition of local forrest fruit extract. Within preparation of encapsulated extracts several methods of preparing lipid or saccharides particles were also tested. The encapsulation efficiency of the methods and stability and size of particles were analysed. Optimal type of fortified cereal foods could be suggested based on the acquired results. Selected cereals were used as alternative carbon substrates (processed or raw) for the cultivation of microorganisms to produce enriched biomass usable in the feed industry. We can conclude that cereals in raw as well as processed form belong to universal foods and rich sources of biologically active substances. They can be processed by many ways. They can be used for direct consumption, as a part of new products and also undirectly as a substrate for feedstock.
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Self-cleaning Properties of Thin Printed Layers of Titanium Dioxide
Králová, Marcela ; Brezová, Vlasta (referee) ; Krýsa, Josef (referee) ; Veselý, Michal (advisor)
Tenké vrstvy oxidu titaničitého byly imobilizovány na sodnovápenatá skla a skelný uhlík použitím jak techniky materiálového tisku tak metodou chemického napařování. Pro přípravu titaničitých solů byly použity metody sol-gelu a nebo hydrotermální syntézy. Struktura připravených vrstev byla zkoumána rastrovací elektronovou mikroskopií a mikroskopií atomárních sil. Krystalická struktura připravených TiO2 byla analyzovány pomocí XRD metody. Fotoindukováná superhidrofility pripravených vzorků byla charakterizována měřením kontaktních úhlů. Fotokatalytická aktivity připravených vzorků byla testována na fotokatalytické oxidaci 2,6-dichlorindofenolu a kyseliny mravenčí. V případě sol-gel vrstev byl zkoumán vliv množství naneseného TiO2 a množství PEG, který byl do solu přidán jako praskliny potlačující činidlo. V případě hydrotermálních vrstev byl zkoumán vliv času a teploty syntézy a množství vrstev na výslednou účinnost vzorku. U chemicky napařených vzorků byl zjišťován vliv intenzity záření. Byla porovnána fotokatalitická aktivita vrstev připravených materiálovým tiskem a chemickým napařováním a byl vyhodnocen nejaktivnější vzorek.
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Nanoparticles preparation by green synthesis
Kortusová, Dominika ; Valušová,, Eva (referee) ; Šimšíková, Michaela (advisor)
This thesis deals with green synthesis of noble metals nanoparticles. The first part contains secondary literature research which maps both the traditional and newly developed techniques of nanoparticles preparation. Most attention is given to the various types of green synthesis, which constitute an environmentally friendly alternative to industrially applied methods. The second part deals with the preparation of noble metal nanoparticles using tea broths. The section describes the entire synthesis process and includes photographic documentation. A total of eight colloidal solutions were prepared, four of each metal. The nanoparticles were subsequently analyzed using UV-vis spectroscopy. A time-lapse spectroscopic description of each synthesis was also undertaken. Furthermore, the size distribution of the particles by volume was measured and compared with the pictures obtained by scanning electron microscopy. The results have showed that tea broths, especially those from black tea and rooibos, are suitable for the biosynthesis of stable noble metal nanoparticles.
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Synthesis of bioceramic materials based on hydroxyapatite
Kočicová, Pavla ; Králová, Marcela (referee) ; Částková, Klára (advisor)
The thesis deals with the precipitation synthesis of nanoparticle hydroxyapatite with goal to study the influence of reaction conditions on the morphology of the particles. The theoretical part is focused on biomaterials, bioceramics and phosphates characterization. Further the work is focused on hydroxyapatite, its characteristics and possible synthesis in particular. The synthesis of hydroxyapatite precipitation is described in the experimental part. Syntheses were performed at a reaction temperature of 0-80 °C at pH = 8-11, at the aging time of 0-24 h, in the presence of surfactant and the chelating agent and with the post-precipitation hydrothermal or ultrasonic treatment. For characterization of the prepared powders, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), laser diffraction (LD) and the analysis of the specific surface area (BET) were used. Pure hydroxyapatite powders or a mixture of hydroxyapatite and tricalcium phosphate were prepared by precipitation syntheses. HA particle morphology was strongly affected by the reaction temperature – with increasing temperature the larger particles with a clearer morphology were formed, mostly in the rod shape. Postprecipitation hydrothermal treatment had a significant influence on the morphology of HA particles – it caused the formation of spherical or slightly elongated particles. The reaction medium of water/ethanol significantly affected the particle morphology – it inhibited the particle growth.
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Surface Plasmon Resonances on Colloidal Nanoparticles
Beránek, Jiří ; Brzobohatý,, Oto (referee) ; Šikola, Tomáš (advisor)
The presented diploma thesis is focused on the Localized Surface Plasmons (LSP). The far-field optical response of the colloidal solutions of gold nanoparticles caused by LSP was investigated and compared with the numerical calculations. For the simulations, the Discrete Dipole Approximation (DDA) and Finite-Difference Time Domain (FDTD) techniques were employed. In particular, the shape and size effects of spherical particles and nanorods were studied. The simulations performed by both methods are in a good agreement for the spheres. For the nanorods, the resonance was found to be affected markedly by their geometry. Also, broader resonance peaks were found. This effect was assigned to the sample size distribution and its influence is discussed by comparing the simulations with experiments. In addition, synthesis of nanorods was carried out as well. Finally, the results on the study of optical properties of silver clusters formed under equilibrium conditions are presented.
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Preparation and properties of ferroelectric ceramic materials
Vykoukalová, Tereza ; Maca, Karel (referee) ; Částková, Klára (advisor)
The aim of the work was a processing of ceramic material based on BST for ferroelectric application. Wet chemical techniques based on precipitations and sol-gel methods with ultrasound, hydrothermal or mechanochemical treatment supporting deaglomeration and reducing particle growth were used for BST ceramic powder synthesis. Suitable powders were selected by the evaluation of particle morphology, size and agglomeration, from these powders BST bulk ceramic with defined phase composition and morphology applicable for ferroelectric applications was prepared. It was found, that the most suitable method for preparation of phase pure and nanosized BST powder was sol-gel synthesis with solvothermal treatment (200 °C/48 h). Ceramic with relative density of 85 % TD and with the average grain size of about 1, 22 µm was prepared by pressing and sintering of the powder synthesized by the sol-gel method.
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Mechanical properties of gel polymer electrolytes
Bárta, Vladimír ; Vondrák, Jiří (referee) ; Sedlaříková, Marie (advisor)
This work deals with the measurement of electrical conductivity and mechanical properties of gel polymer electrolyte containing Lithium ion. Their preparation and performance depends on the concentration of nanoparticles Al2O3 contained therein. The theoretical part deals with the development of gel polymer electrolyte, their use and methods of measurement of electrical conductivity and mechanical properties. In the experimental part describes the preparation of gel electrolyte, the measurement of electrical conductivity, temperature dependence and the measurement of mechanical properties.
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Application of Conductive Inks and Low Temperature Sintered Pastes in PCB Production
Kolek, Andrej ; Špinka, Jiří (referee) ; Starý, Jiří (advisor)
The present masters's thesis informs about the development and application of low-temperature sintering pastes in the manufacture and assembly of PCB components of the enclosing lead-free using nanoparticles of metals and their compounds. Lead-free brazing technology which s using in the present time, which has its drawbacks, however, and thus gaining other appropriate alternatives that seek to replace or further refined lead brazing. The introduction of the theoretical part inform about retrieval method of the type, composition and properties of low-temperature sintering pastes consisting of metal nanoparticles and their compounds. This section describes and explains the reaction mechanisms taking place during the sintering process. The end of the first chapter is dedicated to nanotechnology and production of nanoparticles and their compounds for the needs of the low-temperature sintering and possible related problems. Folowing section is devoted to examples of practitioners of the application and use of low-temperature sintering pastes and tests with which to assess the characteristics and quality of the related sintering conection. At the end of the thesis is a summary perspective and the use of low-temperature sintering technology nanoparticle past into the future. The experimental part is devoted to the application of conductive ink on the base of graphite for the production of 1V, 2V and 4V structures and their electroplated by the copper. There were created technological processes of 2V and 4V structures and test proposed methodologies resistance conductive theme to environmental influences. Filling pasta was tested in implementing 4V structure. There were made microsections various technological applications and their results were processed and evaluated.
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