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Processing of tomographic data by principal component analysis method for archaeological applications
Prokop, David ; Žídek, Jan (referee) ; Pořízka, Pavel (advisor)
Rentgenová počítačová tomografie je metoda sloužící ke 3D zobrazování vnitřní struktury objektů. Mikrostruktura objektů ukrývá důležité informace, které mohou být použity k jejich charakterizaci. Tato práce podává spojení mezi datasety získanými pomocí rentgenové počítačové mikrotomografie a oblastí statistického zpracování dat. Výstupem metody, pak bude klasifikace vzorků na základě informací o jejich mikrostruktuře. Z výsledků klasifikace vzorků, pak můžeme vyvodit různé hypotézy týkající se původu vzorků. Tato práce by mimo jiné mohla sloužit jako takový nový vhled do problematiky kombinace dat různého původu, pomocí metod statistické analýzy.
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Study of Relation between HDPE Internal Structure and Its Cut Growth Resistance SCG (Slow Crack Growth)
Chladil, Martin ; Žídek, Jan (referee) ; Petrůj, Jaroslav (advisor)
This thesis deals with the relation between structure and resistance to failure by the mechanism of slow crack growth (SCG) in HDPE. In the theoretical part there are summarized previously acquired knowledge about the production of PE and about the relation between structure and resistance to failure by the SCG mechanism. In the experimental part, three samples of HDPE with the same melt index MI and the same content of copolymer 1- hexene were synthesized by using three chromium catalysts commonly used for polymerization in industry. There samples were analyzed by GPC-IR-MALS and TREF in order to determine the distribution of side chain branches. The results were discussed with respect to the time to failure FNCT.
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Polymeric nanocomposites - preparation methods
Černý, Miroslav ; Žídek, Jan (referee) ; Kučera, František (advisor)
Literature search of bachelor thesis was focused to methods of CaCO3 nanoparticles preparation, surface modification and PS/CaCO3 nanocomposites processing. Experimental part was based on two methods of PS/CaCO3 nanocomposites preparation: emulsion and bulk technique of styrene radical polymerization in presence of CaCO3 and by compounding CaCO3 with PS in Brabender mixer at 220 °C. Prepared samples were observed using electron microscope.
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Analysis of mechanical properties of polymers and polymer compsites from video record of tensile test
Ščudlová, Jolana ; Nezbedová, Eva (referee) ; Žídek, Jan (advisor)
This thesis described mechanical tests with monitoring of camera. The aim of this work is to obtain additional information about material behavior during the test. The mechanical tests were monitored high-definition (HD) digital video-camera and camera with high resolution. The method was applied to the tensile test and Pennsylvania notch test (PENT test). The videorecordings were processed with the assistance image analysis method. The marks were placed on both of these specimens, mutual movement these marks were used to obtain following characteristics. It was Poisson’s ratio and true stress by tensile test. By PENT test it was rate growth crack. The investigated material was elastomeric polyurethane filled by biodegradable polyhydroxybutyrate for tensile test. Second material was polypropylene for PENT test. The camera is adding to the test gives extended information about the material and better interpretation results.
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Analysis of x-ray diphractograms of organic crystalline solids
Stejkora, Jakub ; Žídek, Jan (referee) ; Salyk, Ota (advisor)
Derivates of diketopyrrolopyrrole are colored pigments with potential use in field of organic semiconductor structures. Their electrical attributes such as conductivity, photocon¬¬ductivity and electroluminescence relate to their crystal structures that determine charge transport path through the compound. For crystallographic structure determination from RTG diffractometry it is needed to grow a measurable single crystal. Growing crystals of derivates of diketopyrrolopyrrols is very difficult due to their poor solubility in all solvents. Several relatively suitable – perhaps even measurable – samples were obtained throughout the testing of series of methods. One of these samples was measured with RTG diffractometry and on the ground of this measurement it was possible to find and solve the crystallographic structure.
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Micro-turning applications in high precision manufacturing performed by diamond tools
Švorc, Josef ; Dvořák, Jaromír (referee) ; Žídek, Jan (advisor)
Bachelor thesis is focused on micro-turning. The work takes the form of a literary research, which aims to make an overview of the production technology. First, it deals with the definition of the topic itself and with the physical properties and phenomena that occur during micro-machining. Then it discusses the construction of micro lathes and their division into categories and compares them to each other. It also deals with the cutting tools suitable for this machining process and their production and shaping. The last part of the thesis is focused on the application and utilization of micro-turning in industry and on the creation of non-rotational components and micro-structures.
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Evaluation of the quality of collagen samples in solid phase using circular dichroism
Ďubašák, Matej ; Žídek, Jan (referee) ; Vojtová, Lucy (advisor)
Diplomová práca sa zaoberá novou kvalitatívnou analýzou kolagénových vrstiev pomocou cirkulárneho dichroizmu v pevnej fáze. Teoretická časť opisuje kolagén a jeho sekundárnu štruktúru, spektroskopické metódy cirkulárneho dichroizmu (CD) a zoslabenej úplnej reflektancie (ATR). Experimentálna časť sa zaoberá prípravou homogénnych a transparentných kolagénových filmov a optimalizáciou objemu, koncentrácie a sušenia. Následne sa zmerala a vyhodnotila kalibračná krivka s rôznymi pomermi kolagénu a želatíny. Získaná rovnica lineárnej regresie sa použila na stanovenie obsahu kolagénu v modifikovaných vzorkách. Výsledky hodnotených modifikovaných vzoriek boli porovnané s meraniami ATR spektroskopie. Merania ATR ukázali vyšší obsah kolagénu ako CD merania. Vzorky s najnižším a najvyšším obsahom kolagénu sú pre obe metódy rovnaké. Dokazuje to, že môžme porovnávať vzorky s rôznym obsahom kolagénu navzájom, ale nemôžeme určiť presný obsah kolagénu pripojením týchto dvoch metód. Optimalizovaná metóda CD sa môže použiť na prípravu a meranie presného obsahu kolagénu vo vzorkách, najmä v rámci výroby kolagénu, aby sa dosiahla konštantná kvalita kolagénu v každom kroku výroby.
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Influence of Solvent on Deformation Behavior of Hydrogels
Kulovaná, Eva ; Bartlová, Milada (referee) ; Mráček, Aleš (referee) ; Žídek, Jan (advisor)
The thesis deals with molecular dynamic simulation of the influence of water on the deformation of hydrogels. Hydrogels are model materials formed from macromolecular networks solvated with water. It was found that water can form bridges between macromolecules that take the form of temporary ionic crosslinks. These bridges affect the behavior of the network during deformation. Water bridges are water molecules that have a limited radius of motion in the space between two macromolecules. The concentration of the water bridges was regulated by a partial charge on the macromolecular chain in the organic network. Bridges are a type of interaction that is relatively strong but significantly delocalized. It is not possible to dissociate the water bridge, after dissociation it will be re-created in another place in a short time. The influence of water bridges was compared with other types of network crosslinks, especially covalent and physical bonds. Covalent crosslinks are modeled as a simple binding interaction between two macromolecules. They are undissociable and are local throughout the simulation. Physical bonds are modeled as micelles, where hydrophobic groups form the core and hydrophilic groups form the micelle shell. Physical bonds have the nature of dissociable bonds that are local. Different types of crosslinks have different effects on deformation properties. The deformation of a network containing a combination of two types of crosslinks was simulated: (i) physically-covalent, (ii) ionically-covalent, and (iii) physically-ionic networks and (iv) ternary physically-covalent-ion networks. For individual and combined networks, the behavior depending on simple networks was verified. The number of water bridges was fundamentally affected by the primary structure of the chains. When the PEG chain was replaced with hydrophobic polyoxymethylene (POM) or polyoxytrimethylene (POTM), their solvation and mechanical behavior deteriorated.
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