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Influence of zinc loss during the sintering on permeability/inductance of ferrite ceramics
Kvapilová, Vendula ; Ptáček, Petr (referee) ; Šoukal, František (advisor)
The diploma thesis is focused on the investigation of the effect of zinc release during ferritic sintering on the permeability/inductance of ferrite ceramics. The theoretical part deals with the position of ferrites among other ceramic materials. It describes the basic characteristics of ferrites, their crystal structure and finally the problems that are directly related to their production and which fundamentally affect the magnetic properties of ferrites. In the second part of the work, the influence of the temperature and time of sintering and the position of the cores in the furnace during firing on the loss of zinc from the sample and subsequently on the electromagnetic properties of the prepared test specimens from industrial raw material mixtures was investigated. These are initial experiments, which will be followed by further research aimed at eliminating the problem of zinc loss in the production of Mn-Zn ferrites.
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Study of cholesterol depletion in human skin barrier
Jančálková, Pavla ; Vávrová, Kateřina (advisor) ; Nováková, Veronika (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Organic and Bioorganic Chemistry Pavla Audrlická Supervisor: prof. PharmDr. Kateřina Vávrová, Ph.D. Title of diploma thesis: Study of cholesterol depletion in human skin barrier Barrier function of human skin barrier dwells in intercellular lipid membranes of the uppermost skin layer, the stratum corneum (SC), composed of equimolar mixture of ceramides (Cer), free fatty acids (FFA) and cholesterol (Chol).1 Chol is required for proper lipid organization of SC, however, it stays unclear, why is it present in an amount so high that it separates from other lipids.2 Experiments using synthetic model membranes with decreased Chol content suggested that molar ratio of Cer:FFA:Chol 1:1:0,4 is sufficient for lipid barrier formation and its complex functionality.3 The aim of this work was to manipulate Chol content directly in human SC and to study the effects of decreased Chol content on the SC permeability and microstructure. Ex vivo SC obtained from healthy donors was extracted by methyl-β-cyclodextrin (MCD) to reduce natural Chol content. The extracted SC did not show significant changes in Cer or FFA whilst the amount of Chol was lowered to 78 %. SC barrier properties were evaluated by measurements of transepidermal water loss...
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Influence of high temperatures on concrete properties
Klobása, Jan ; Křížová, Klára (referee) ; Sedlmajer, Martin (advisor)
The aim of this bachelor thesis is to study the problem of the behavior of concrete under high temperatures. The theoretical part of the work summarizes the knowledge about the changes that take place in concrete when it is exposed to a high thermal load that simulates the effects of fire. It also summarizes the effect of high temperatures on the behavior of the individual components that make up concrete. Emphasis is placed on describing the possibilities of eliminating concrete damage at high temperatures. Furthermore, the principles of changes and events due to high temperatures simulating the effect of fire are described. The experimental part summarizes the knowledge related to the composition of concrete, the use of different types of fibers, and other measures in loading concrete at high temperatures. Steps influencing the negative impact on the properties and resistance of concrete to high temperatures are also described. Based on the summarized findings, conclusions are formulated.
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Study of cholesterol depletion in human skin barrier
Audrlická, Pavla ; Vávrová, Kateřina (advisor) ; Nováková, Veronika (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Organic and Bioorganic Chemistry Pavla Audrlická Supervisor: prof. PharmDr. Kateřina Vávrová, Ph.D. Title of diploma thesis: Study of cholesterol depletion in human skin barrier Barrier function of human skin barrier dwells in intercellular lipid membranes of the uppermost skin layer, the stratum corneum (SC), composed of equimolar mixture of ceramides (Cer), free fatty acids (FFA) and cholesterol (Chol).1 Chol is required for proper lipid organization of SC, however, it stays unclear, why is it present in an amount so high that it separates from other lipids.2 Experiments using synthetic model membranes with decreased Chol content suggested that molar ratio of Cer:FFA:Chol 1:1:0,4 is sufficient for lipid barrier formation and its complex functionality.3 The aim of this work was to manipulate Chol content directly in human SC and to study the effects of decreased Chol content on the SC permeability and microstructure. Ex vivo SC obtained from healthy donors was extracted by methyl-β-cyclodextrin (MCD) to reduce natural Chol content. The extracted SC did not show significant changes in Cer or FFA whilst the amount of Chol was lowered to 78 %. SC barrier properties were evaluated by measurements of transepidermal water loss...
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The evaluation of the effect of crystallization additives on durability cement composites
Roubal, David ; Bydžovský, Jiří (referee) ; Dufka, Amos (advisor)
This bachelor´s thesis deals with the study of crystalline materials and their effects on the durability of concrete. The theoretical part of this thesis focuses on the detailed analysis of the characteristics of crystalline materials, including their division and use. It also particularizes the main factors influencing the durability of concrete and provides an overall research of crystalline materials testing. Based on the findings, the experimantal part focuses on the examination of crystalline materials applied to self-compacting concrete. The examination included, among other things, testing in aggresive environment and strength and permeability test carried out on set SCC.
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Design and Realization of Metamaterial
Kovaľová, Soňa ; Drexler, Petr (referee) ; Nešpor, Dušan (advisor)
The thesis discusses the design of periodic resonant structures, studying of their impact to surrounding electromagnetic field and realisation of magnetoinductive lens with potential application in nuclear magnetic resonance imaging. Frequency tuning of structure by variation of different parameters is described. The finite element method in Ansys HFSS was used to analyse the properties of designed structures.
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Measurement of Dialyser-Membrane Diffusion Coefficient
Kašák, Pavel ; Bartoš, Michal (referee) ; Jiřík, Radovan (advisor)
This thesis focuses on the measurement of diffusion coefficient of dialysis membrane. The first part describes possibilities of membrane modelling. Basic models, which allow us to determine the basic characteristics of dialysis membranes like permeability and diffusion coefficient, are described. Next chapter deals with basic types and properties of membranes. The main part focuses on making the experimental installation, which is used to simulate permeance of contrast agent, used in DCE-MRI, through dialysis membrane. The last theoretical chapter describes calculations used to estimate diffusion coefficient. Practical part of this thesis uses a designed experimental installation for estimation of diffusion coefficient for two contrast agents Gadovist® and Multihance®.
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Model of synchronous PM machine based on equivalent reluctance network
Sporni, Peter ; Lapčík, Josef (referee) ; Ondrůšek, Čestmír (advisor)
Táto práca pojednáva o problematike vytvárania a simulácie reluktančnej sieti synchrónneho stroja s V tvarovanými permanentnými magnetmi v programe PSpice. Na začiatku sa oboznámime s konštrukciou a parametrami stroja a potom vyvodíme základné rovnice na výpočet každého prvku siete. Vypočítame každý prvok tohto stroja a potom vytvoríme túto sieť v PSpice. Na začiatku je simulovaná sieť statická a všetky magnetické odpory sú lineárne. Neskôr nahradíme lineárne odpory reprezentujúce plechy nelineárnymi a počítame s precovnou teplotou permanentných magnetov. Potom porovnáme naše výsledky s FEM metódou počítanými hodnotami a vypočítame indukované napätie v jednej cievke stroja. Na záver vypočítame výkonovú a momentovú charakteristiku stroja.
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Porous elements based on granular materials and inorganic binders
Bulejko, Pavel ; Dohnal, Mirko (referee) ; Svěrák, Tomáš (advisor)
Tato diplomová práce zkoumá možnosti tvorby porézních struktur za použití partikulárních materiálů pojených anorganickými pojivy bez dodatečné tepelné úpravy vypalováním. Jako základní pojiva byly použity portlandský a hlinitanový cement a pojiva na bázi alkalicky aktivovaného metakaolinu (geopolymeru). Jako základní kamenivo byl použit karbid křemíku v různých frakcích podle velikosti částic. Byly taktéž použity další zrnité materiály, např. křemenný písek anebo odpadních materiálů (mleté sklo a porcelán) roztříděných do frakcí podle velikosti částic. Byl sledován vliv složení a množství kameniva na vytváření porézní struktury a tím i na mechanické vlastnosti, které byly testovány pomocí mechanických zkoušek. Pevnostní zkoušky byly provedeny na trámečcích 20 × 20 × 100 mm připravených z testovacích směsí. Granulometrické a fázové složení vstupních surovin bylo studováno metodou laserové granulometrie resp. RTG difrakce. Porézní struktura byla studována metodami rtuťové porozimetrie, dále pomocí světelné a rastrovací elektronové mikroskopie a taktéž pyknometrickou metodou. V rámci charakterizace přepážek (terčíky o průměru 90 mm) připravených z jednotlivých materiálů bylo provedeno stanovení efektivní permeability průtokem vzduchu. Dále byly provedeny testy vzlínavosti kapaliny v připravených materiálech. V závěru práce byly provedeny pokusy o filtraci jemných suspenzí přes uvedené přepážky.
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