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Bioceramic Materials for Advanced Medical Applications
Novotná, Lenka ; Lapčík,, Lubomír (referee) ; Drdlíková, Katarina (referee) ; Cihlář, Jaroslav (advisor)
Cílem disertační práce bylo připravit trojrozměrné biokeramické podpůrné systémy („skafoldy“), které by v budoucnu mohly pomoci při rekonstrukci a regeneraci poškozených kostních tkání. Porézní keramické pěny byly připraveny dvěma způsoby – replikační technikou a polymerizací in situ. Co se složení týče, byly studovány keramické materiály zejména na bázi oxidu hlinitého, zirkoničitého a kalcium fosfátů. Byl studován jednak vliv procesních parametrů jako je složení suspenzí a jejich viskozit, dále pak vliv tepelného zpracování na strukturu a výsledné vlastnosti připravených materiálů. U slinutých pěn byla pomocí rastrovací elektronové mikroskopie hodnocena zejména morfologie – velikost pórů, jejich propojenost a celková porozita, charakterizace mikrostruktury nebyla opomenuta. Dále bylo stanoveno fázové složení a pevnost v tlaku. Z biologických vlastností byla testována a diskutována bioaktivita a cytotoxicita materiálů. Disertační práce je členěna do několika částí. V literární rešerši je popsána stavba a vlastnosti kosti, požadavky kladené na kostní náhrady, výhody a nevýhody současně používaných materiálů a způsoby přípravy keramických pěn. Následuje experimentální část, kde byly nejprve studovány pěny připravené replikační technikou. Všechny takto vyrobené pěny měly propojené póry o velikostech 300 až 2000 m, celková porozita se pohybovala v rozmezí 50 – 99 %. Pevnost pěn na bázi kalcium fosfátů – 0,3 MPa (při celkové porozitě 80%) byla nedostatečná pro kostní náhrady, kde je požadována pevnost větší než 2 MPa. Kalcium fosfátové keramiky byly tedy zpevněny buďto inertním jádrem na bázi oxidu hlinitého nebo ATZ (oxidem zirkoničitým zhouževnatělým oxidem hlinitým). Dále byl přípraven částicový kompozit, ve kterým byl hydroxyapatit pojený oxidem křemičitým. Pevnost pěn se podařilo zvýšit až na více než 20 MPa. V poslední kapitole experimentální části byly studovány keramické pěny pěněné in situ, kde byly póry vytvářeny oxidem uhličitým unikajícím během reakce mezi diisokyanátem a polyalkoholem. Po vypálení polymerního pojiva měly pěny propojené póry o průměrné velikosti 80 až 550 m. Celková porozita se pohybovala v rozmezí 76 – 99%. Výhodou oproti replikační technice byly plné trámečky bez velké středové dutiny vznikající vypálením polymerní předlohy. Žádný ze studovaných materiálů nebyl pro buňky toxický, navíc všechny studované pěny vykazovaly bioaktivní chování. Z hlediska kostního tkáňového inženýrství se jako nejslibnější jeví kompozitní materiál zpevněný oxidem křemičitým.
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Tailoring of cooling procedure during freeze-casting for bone replacement applications.
Šantavý, Tomáš ; Novotná, Lenka (referee) ; Salamon, David (advisor)
Bachelor thesis focuses on preparation of hydroxyapatite ceramics by freeze-casting. Hydroxyapatite is an important ceramic material, due to its biocompatibility, biodegradability and bioactivity it has a wide range of use in medicinal applications especially in replacement of bone material. The chosen method, freeze-casting, is flexible, eco-friendly and we are able to achieve a high level of porosity. The method includes freezing, freeze drying and sintering which creates a porous structure of the prepared material. Objective of this bachelor thesis was to find out the impact on the created porosity and mechanical properties of the final material. Freezing rates were applied 3, 4, 5, 6, 7 and 26 m/s. During the experimental part it was established that the freezing rate has a significant influence on the newly formed inner microstructure, it directly influences the interlamellar distances and mechanical property which is compressive strength. With liquid nitrogen with a speed of 26 m/s the achieved compressive strength was of 15 MPa as well as the shortest interlamellar distances of 14-22 µm. With slower freezing rate the average interlamellar distances were 40-150 µm and compressive strength of 2-4 MPa with comparable porosity.
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Statistical Methods for Description of Running a Restaurant
Novotná, Lenka ; Doubravský, Karel (referee) ; Kropáč, Jiří (advisor)
The diploma thesis is written with a view to illustrate application of statistical methods describing progress of economical processes in company. The thesis is divided into two separated parts. First part focuses on theoretical pieces of knowledge about control charts and time series. Second part is composed from chapters that are focused on its practical usage. As simple application for control chart making is enclosed.
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Impact of the company's allocation to optimize its operation using the principles of facility management
Novotná, Lenka ; Fellow, Ondřej Štrup, IFMA (referee) ; Hromádka, Vít (referee) ; Somorová,, Viera (referee) ; Tichá, Alena (advisor)
A number of partial restructuring measures are offered to optimize business operation to improve its efficiency and performance. The structure inside the company is one of the most important tools for managing its performance and its correct definition, and a proper and meaningful distribution can play a key role in the competitive environment. In many cases, the requirement for optimization of operation will arise from the requirements of facility management, and therefore restructuring measures relating to organizational changes should be implemented with respect to the principles of facility management or should be based on its optimization. This thesis presents the impact of restructuring measures by centralizing of divisions on optimizing its operation with respect to the facility management. The aim of the dissertation is to evaluate the organizational change in the company with several divisions, taking into account the principles of facility management. The result of this thesis are the methodical recommendations during the establishment and evaluation of the division´s centralization in the company. It is based on the findings from the literature review and the real change in the building company.
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Shaping of bioceramic hydroxyapatite scaffolds on micro level
Pejchalová, Lucie ; Novotná, Lenka (referee) ; Salamon, David (advisor)
Due to increasing average age of population around the world, there are more patients who need surgery of musculoskeletal system. In some cases, it is even necessary to implant new bone scaffold or replace joints. Hydroxyapatite is the most frequently used material for its biocompatibility and bioactivity. On the other hand, mechanical properties constraints its use in porous scaffolds. The method providing both good mechanical stability and high porosity is freeze – casting. This method utilises controlled freezing to form lamellar structure. During freezing of slurry, ice crystals grow in direction of temperature gradient. In next step, ice crystals are removed by lyophilisation and lamellar structure is revealed. This structure is relatively unstable and needs to be reinforced by sintering. There are many aspects affecting resulting structure – freezing schedule, slurry concentration etc. We used water/ceramic slurries in various concentrations of hydroxyapatite (7,5 % vol., 10 % vol., 15 % vol. and 20 % vol.). These slurries were used for preparation of porous bone scaffolds. We tried to add 3D mash to form net of channels and we observed favourable changes in porosity. 3D mash was removed during sintering. Resulting bioceramics structure was highly porous (up to 90 %). These scaffolds had an acceptable ration between porosity and mechanical stability, too. We considered, adding of 3D mash, as good way to form channels of desired properties.
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3D Printing of Ceramic Bone Grafts with Different Internal Architecture
Novotná, Lenka ; Sekora, Jiří (referee) ; Provazník, Ivo (advisor)
Bioceramics in the form of scaffolds hold great promise in bone tissue regeneration. While the scaffold composition is important for biocompatibility, the internal architecture plays a key role in allowing proper cell penetration, nutrient diffusion, bone ingrowth, vascularization as well as mechanical properties. A solid freeform fabrication is a promising processing technique, allowing to study structural parameters independently. This bachelor thesis is focused on ceramic bone replacements with different internal structure. The thesis is divided into 8 chapters. The first four chapters briefly summarize the current state of the art in the following fields: bone structure, requirements for synthetic bone replacements, scaffold architecture, and fabrication methods with an emphasis on 3D printing. The next chapters deal with experimental part. The image analysis of mouse skeleton was performed. On the basis of the measured pore size (50 200 m) and according to the literature search, 16 structures with various shape, curvature and pore size were designed. The CAD models were printed by a stereolithography from a tricalcium phosphate dispersion. Sintered ceramic scaffolds exhibited an ideal structure for application in bone tissue engineering. Scaffolds contained both interconnected macro- and micropores of optimal sizes up to 500 m and about 3 m, respectively. The results confirm that stereolithography is suitable, and compared to others, precise method for preparing scaffolds having different internal structures. The individual structural characteristics influencing the scaffold behaviour will be possible to study independently to each other. And thus improve the scientific knowledge in the field of treatment of large segmental bone defects.
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Bioceramic materials bioactivity testing via simulated body fluid
Holbusová, Eva ; Novotná, Lenka (referee) ; Salamon, David (advisor)
These days, there is a possibility of joint replacement implantation, more common dental implants, or regeneration of bone fractures using bone graft replacements is more accessible than in history. Bioceramic materials are used for these purposes. Bioceramics is a non-toxic ceramic material. It is characterized by its bioactivity and biocompatibility. Bioactivity testing of bioceramics is performed using simulated body fluid (SBF). In addition, the change in the concentration of calcium ions was investigated during the testing. The aim of the work was to determine whether the concentration of calcium ions changes between bioceramics and SBF. Bioceramic samples were prepared by two methods, namely freeze-casting and cold isostatic pressing. What was soaked in c-SBF was prepared according to Kokubo. The analysis of SBF was performed using a colorimetric method with a reagent of Murexide solution and reagent KIT. The concentration of calcium ions in the SBF after soaking samples in a testing cycle 0, 3, 7, 14, and 21 days was measured using a UV/VIS spectrophotometer. In addition, X-ray diffractometry was used to determine the phase composition of the material before soaking in SBF. The change in calcium ion concentration during the test cycle in the bioceramic – SBF system was confirmed with UV/VIS spectrophotometry. The most significant increase in concentration was recorded on the third day of soaking. The assumption of an apatite layer formation on the soaked bioceramic samples was supported by a change in the concentration of calcium ions SBF and the change in weight of the material after soaking. It was found that using indirect colorimetric determination delivered better results when the Murexide indicator was used instead of KIT.
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Processing and properties of porous bioceramic materials
David, Jakub ; Ručková, Jana (referee) ; Novotná, Lenka (advisor)
Bachelor thesis is focused on the study of bioceramic porous materials. The theoretical part is divided into three parts. The first part describes biomaterials, their division and use in bone tissue engineering. The second part deals with the requirements of bioceramic support systems (scaffolds). The third section describes methods for the porous structures production. The effort of the practical part was to prepare by method of direct foaming bioceramic porous materials based on calcium phosphate. It studied mainly the affect of the suspension composition on the final properties of the synthesized material. Morphology of materials was also evaluated using scanning electron microscopy. Degradability of materials in simulated body fluid was tested in terms of biological properties.
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