National Repository of Grey Literature 27 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Hydration Process of Magnesium Oxide from Partly Calcined Dolomite
Tišnovský, Michal ; Bartoníčková, Eva (referee) ; Ptáček, Petr (advisor)
This bachelor thesis deals with the study of half-burnt dolomite, it‘s thermal decomposition (calcination) and preparation of a mixture of magnesium hydroxide and calcium carbonate by precipitation. At the beginning of the experimental part, the dolomite material sample is characterized. It‘s moisture content, double magnesium carbonate content and other carbonates are found. The second part deals with the study of the burning process in which a suitable interval of thermal treatment temperature was found. The investigation of the dissolution of dolomite in hydrochloric acid revealed the reaction kinetics. For precipitation, a method based on boiling a dolomite suspension in a hydrochloric acid solution under reflux, was used. The precipitation product in this case was magnesium carbonate in the modification of aragonite.
Study of interaction of HA / biosklo based composites in simulated body fluid
Riša, Juraj ; Švec, Jiří (referee) ; Bartoníčková, Eva (advisor)
This work deals with bioceramic materials based of hydroxyapatite, bioglass and their composites. These materials are commonly used in medicine, especially as hard tissue substituents. They can be prepared by different types of syntheses, from which the most common were picked for this work – precipitation of hydroxyapatite and sol-gel method for bioglass. Thermal analysis and X-ray diffraction were used for characterization of prepared powders. This thesis studies mostly their features within the composite materials, which were foamed for better bone stimulation. Properties and possibility in bio application of materials is firstly studied through their interaction in simulated body fluids, which mimics ionic concentration of human plasma. Experimental part covers synthesis of ceramic powders, their characterization, preparation of mixtures and scaffolds foamed through in situ foaming, their sintering at ideal temperatures, characterization of porosity and phase changes due to sintering. Basic tests of apatite formation ability were provided by incubation of prepared scaffolds in simulated body fluid for 3, 7, 14 and 21 days and their assay in scanning electron microscopy. Changes in concentration of Ca2+ a PO4 3- ions as well as in weight of the specimen were tracked within the incubation period.
Fabrication of dental glass-ceramics
Hasalíková, Tereza ; Dlabajová, Lucie (referee) ; Bartoníčková, Eva (advisor)
This bachelor´s thesis deals with the study of glass-ceramic materials and their use in dentistry. Nowadays, studies are placed on health harmless of the material, the biological ability to adapt to the host tissue, mechanical properties, affordability, easy and fast production, aesthetics and quick recovery of the patient. The theoretical part of the work deals with various materials from various input materials used for dental substitutes. Special attention is paid to glass-ceramic and ceramic biomaterials, their preparation, heat treatment and health testing. The experimental part deals with the preparation of powder materials by the sol-gel method. Of the larger number of samples, those were selected for gelation and showed good XRD and heat microscopy results. The selected samples were subsequently subjected to heat treatment to form a glass ceramic material. The products were characterized by XRD phase composition in terms of phase temperature behavior by TG-DTA analysis, heat microscopy and SEM morphology analysis of prepared particle.
Methodology for determining the chemical composition of water glasses
Flídrová, Michaela ; Bartoníčková, Eva (referee) ; Kalina, Lukáš (advisor)
The bachelor thesis deals with the methodology of determination of the chemical composition of water glasses. The aim was to find a more suitable method than the colorimetric analysis used by one of the domestic water glass manufacturers. The current procedure can be used to determine the content of Me2O (Na2O, K2O, Li2O), however, in the determination of SiO2 the method is inaccurate since the color change of the indicator during the second titration is very slow and therefore the equivalence point is ambiguous. The main aim of this work was to find a suitable method for the complex determination of the chemical composition of water glasses, which is compared with other methods used in the analytical chemistry of silicate materials. A very promising method is the conductometric titration with a volumetric hydrochloric acid solution, which provides an accurate, fast and instrumentally inexpensive method of chemical determination.
Possibilities of enhancement of kaolin whiteness
Krahulová, Veronika ; Bartoníčková, Eva (referee) ; Opravil, Tomáš (advisor)
This thesis focuses on problematics of increasing the kaolin whiteness index. The aim of the thesis is to verify possibilities and efficiency of the mechanical method of increasing whiteness of kaolin using sand of a defined fraction. This method cannot be considered as a whitening operation of kaolin but as a pre-treatment of the raw material or as one of the steps in increasing the whiteness. There have been tested diverse proportions of added sand with which the batch of kaolin material was intensively mixed for various times. Moreover, there has been tested influence of water and total batch volume. To characterize prepared samples there have been used several methods; XRF and XRD analysis was used to determine the elemental and phase composition of raw kaolin before and after mechanical sand action. The UV - VIS method with reflectance was used to assess the achieved whiteness.
The influence of simulated body fluids on the apatite production
Horváthová, Lenka ; Beranová, Denisa (referee) ; Bartoníčková, Eva (advisor)
This bachelor thesis deals with the interaction of various simulated body fluids with ceramic biomaterials. It includes fluid preparation, sample preparation and subsequent analysis of their interaction. Individual samples of biomaterials were exposed to a simulated body fluid for a certain amount of time. After this time, a change in the calcium and phosphorus content of the solutions was determined. At the same time, an electron microscope analysis of sample surface was performed where the dependence of calcium and phosphorus changes was demonstrated. Electron microscopy analysis revealed the formation of new phases on the surface of the studied materials.
Kaoline whitness improvement by mechano-chemical treatment
Uher, Samuel ; Bartoníčková, Eva (referee) ; Šoukal, František (advisor)
The thesis deals with the issue of increasing the whiteness of kaolin by acid leaching simultaneously with milling. Kaolin was prepared from kaolin raw material from the Otovice quarry (Sedlecký kaolin a.s.), which was subsequently grined in suspension with oxalic acid, tartaric acid or citric acid in a ball planetary mill. We had been observing the influence of the type and concentration of acid and grinding time on many aspects, such as: the whiteness index, the amount of leached Fe and Ti, the distribution of Fe and Ti in kaolin, and the kaolin structure order.
Hydroxyapatite based ceramic composites
Vojtíšek, Jan ; Ptáček, Petr (referee) ; Bartoníčková, Eva (advisor)
This work was focused on the study of hydroxyapatite based bioceramic materials. These materials are generally very important for medical purposes, especially in the reconstruction and replacement of bone material. For medical applications, inert, bioactive or bioresorbable materials can be used. One of the common "bioactive" materials is hydroxyapatite, which forms a large part of human bone. Hydroxyapatite can be prepared by a wide variety of procedures, one of the most common methods is the precipitation reaction used in this work. To improve the biocompatibility of the bone replacement, porous structures with adequate mechanical stability are used. For the initial study of simulation of the behavior of biomaterials in the human body, called in vitro tests are used in solutions based on synthetic body fluids or cell media. The experimental part deals with the synthesis of hydroxyapatite powder and CA phase composite compounds. The reactions between the individual components were studied by thermal analysis and heat microscopy. The resulting products were analyzed for phase composition by X-ray diffraction. The prepared powders were further processed on foam structures by in situ foaming and sintering at a suitable temperature. In vitro tests, following the behavior of the prepared porous products in the synthetic body fluid, were performed for 7, 14 and 28 days. The monitored composites were then studied for biocompatibility by scanning electron microscopy. At the same time, the change in the concentration of Ca2+ and PO43- ions in the body fluids tested was monitored.
Synthesis of ceramic materials based on Ca-Co-O system
Žáková, Kateřina ; Švec, Jiří (referee) ; Bartoníčková, Eva (advisor)
In this work synthesis of structure cobaltites based on Ca-Co-O system is discussed. As major way of synthesis was chosen citric acid method. The document is devided into theoretical and experimental part and also into discussion of observed results. Main focus of literary research is general utilization and function of thermoelectric materials, related thermoeletric effects according to structural defects in crystals. Also topic of cobaltite ceramics is described. Due to the fact that calcium-cobalt oxides are conductive, their use is point of interest in high-temperature and energy applications. During experiments differential thermal and thermogravimetric analysis (TG-DTA), X-Ray diffraction, heat microscopy and scanning electron microscopy were used.
Synthesis of bioactive glass for medical application
Wiederová, Kristýna ; Galvánková, Lucie (referee) ; Bartoníčková, Eva (advisor)
In this bachelor’s thesis, the 45S5 bioactive glass was synthesized via sol-gel method. Alternative precursors as colloidal silicas as a silicon source and phosphorous acid, ammonium hydrogenphosphate and ALUFOS were used. Three dierent gel ageing procedures were tested. The nine dierent samples were synthesized and analyzed. The dependence of the fnal properties of the products on the type of precursors has been confrmed. The dependence on the preparation process has not been confrmed within this thesis.

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