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Preparation of Ag/Co/Ag Trilayers
Burda, Pavel ; Kolíbal, Miroslav (referee) ; Čechal, Jan (advisor)
The Bachelor's thesis is aimed to the preparation of silver and cobalt ultrathin films. The films are formed on modified surfaces of crystalline silicon substrates (SiO2/Si(111), Si(111) ?H, Si(111) 7×7) and amorphous SiO2 in a form of a quartz glass. Thin films are grown using an effusion cell for Molecular Beam Epitaxy (MBE). Surface modified surfaces are covered subsequently by a silver, cobalt and silver thin layer. The individual film thickness is 6 nm. Consequently the samples are studied by the X-ray Photoelectron Spectroscopy (XPS) and the Atomic Force Microscopy (AFM). The morphology of thin films and growth modes are compared among the substrates. Growth modes change with the surface modification type. Complete trilayer system Ag/Co/Ag was prepared on SiO2/Si(111) and Si(111) 7×7. Such system can be employed in plasmonics in order to allow the control of surface plasmon polariton properties by an external magnetic field.
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Biocompatible titanium and cobalt alloys and their aplications
Volná, Kateřina ; Kohout, Jan (referee) ; Věchet, Stanislav (advisor)
This work is written in the form of literary research and deals with titanium and cobalt alloys and their application in dental medicine. Production of the individual metals, their mechanic, physical as well as chemical characteristics and various alloys which these elements can form are described in the first part. Furthermore, biocompatibility and basic division of biocompatible materials are explicated here. The work also deals with the basic requirements placed upon the materials used in dental medicine. Subsequently, five particular alloys are introduced: Ti-6Al-4V, Nitinol, Oralium, Oralium Ceramic and Ceramill Sintron and their characteristics and usage are described. In conclusion, the individual metals and their alloys are evaluated.
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Microdetermination of cobalt by methods of molecular and atomic absorption spectrometry
Charuza, Martin ; Řezáčová, Veronika (referee) ; Sommer, Lumír (advisor)
This diploma thesis is focused on microdetermination of cobalt by UV-VIS spectrophotometry with organic agents and comparison with atomic absorption spectrometry. In the first part properties, occurance and importance of cobalt in the environment are desribed, complete with as a part of vitamine B12. Attention is also given to cobalt compounds, especially in the oxidative states +II and +III. Methods of preconcentration and preparation cobalt determination in real samples are adduced. In this thesis are described some optical analytical methods with accept on spectrophotometric agents for determination of cobalt. The experimental part of this thesis icludes optimalization of the spectrophotometric determination of cobalt with choosen organic agents 4-(2-pyridylazo)resorcin and 2-(5-Brom-2-pyridylazo)-5-diethylaminophenol and optimalization of atomic absorption spectrometry for cobalt determination. All of real samples of water (surface, underground, mineral and waste) were measured by both 4-(2-pyridylazo)resorcin and 2-(5-Brom-2-pyridylazo)-5-diethylaminophenol via UV-VIS and via atomic absorption spectrometry. Results of determinations were compared. A sample of vitamine B12 was measured too by all techniques.
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Structure and Properties of Sintered Tungsten Carbides
Novotná, Hana ; Klakurková, Lenka (referee) ; Čelko, Ladislav (advisor)
This bachelor thesis deals with the structure and properties of sintered tungsten carbides. The literature review section concerns the development of sintered carbides, their composi-tion and structure, different types of carbides, the steps of the production of sintered car-bides, sintering technology and alternative materials for cutting tools. The experimental section deals with composition of WC-Co and is ascertained by the dependency coercivity on WC grain size and also on cobalt content. This work describes the measurement of WC grain size and measurement of the coercivity, one of the fundamental properties of sintered carbides.
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Selective growth of metallic materials.
Šimíková, Michaela ; Schneeweiss, Oldřich (referee) ; Čechal, Jan (advisor)
The diploma thesis deals with selective growth of cobalt thin films on lattices created by focused ion beam on Si(111) substrates with thin film of silicon dioxide. Further, the growth and morphology of iron thin films growing on Si/SiO2 substrate without modification was studied. In the last part, thin film of a-C:H, influence of preparation parameters on their growth and ratio of sp2 and sp3 bonds, was investigated. For analysis of those films XPS, AFM, and SEM metods were used.
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The influence of cobalt additive on parameters of positive electrode for Ni-Cd accumulators
Svoboda, Michal ; Svoboda, Vít (referee) ; Špičák, Petr (advisor)
The Master´s thesis deals with description of the influence of cobalt additive on positive electrode parameters for Ni-Cd accumulators. Trough the use of Electrochemical Quartz Crystal Microbalance are analysed the effects which decline effective life of positive electrode during accelerated cycling. Theoretical part describes important characteristics of Ni-Cd accumulators, the working principle and effects which are in progress on positive electrode during cycling. The next part deals with description of system EQCM and the pricnciples of doping active mass with cobalt additive. Practical part consists of EQCM system calibration and electrochemical measurements. The principal aim is detection of the influence of cobalt additve on active mass during cycling in different electrolytes. From the results of measurements is set the optimal amount of cobalt additive.
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The evaluation of senescence markers in the H9c2 cell line after cobalt exposure
Rottenbornová, Lucie ; Jirkovský, Eduard (advisor) ; Hrubša, Marcel (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology and Toxicology Student: Lucie Rottenbornová Supervisor: PharmDr. Eduard Jirkovský, Ph.D. Title of diploma thesis: The evaluation of senescence markers in the H9c2 cell line after cobalt exposure Introduction and aim: Cellular senescence is the response of a cell to a physiological or stressful stimulus. Cobalt is an element that simulates hypoxia under normoxic conditions through hypoxia-inducible factors. One of the factors that can induce cellular senescence is hypoxia. The aim of the work was to evaluate p16INK4a and Ki67 proteins as markers of cell senescence in an H9c2 cell line after exposure to CoCl2. Methods: Cytotoxicity was measured using the MTT assay on the H9c2 cell line after 24 and 48 hours of exposure to CoCl2. Subsequently, relative gene expression of genes associated with hypoxia (HIF1α and BNIP3) and senescence (p16INK4a and Ki67) in H9c2 after exposure to cobalt was investigated using the RT-PCR method. Results: Exposure of H9c2 cells to CoCl2 induced dose- and time-dependent toxicity. After a 24-hour exposure, CoCl2 toxicity was not observed up to a concentration of 100 μM, the IC50 value was 500.5 μM. After 48 hours of exposure, higher toxicity was observed already at 100 μM concentration and...
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Searching for natural cobalt chelators
Kadlecová, Kateřina ; Karlíčková, Jana (advisor) ; Carazo Fernández, Alejandro (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacognosy and Pharmaceutical Botany Student: Kateřina Kadlecová Supervisor: PharmDr. Jana Karlíčková, Ph.D. Title of diploma: Searching for natural cobalt chelators Cobalt, as a trace element, is mostly found in the human body as the central atom of vitamin B12. Its deficiency is manifested by psychological impairment, memory loss, dementia or megaloblastic anemia. In excess amount, it is toxic to the body, which has been most described in patients with MoM hip replacement surgery. Cobalt causes damage to surrounding tissue until it is destroyed, or also cardiotoxicity, thyroid hypofunction, memory and hearing loss. Flavonoids are natural polyphenolic compounds with the ability to bind metals, scavenge free radicals and hence protect against oxidative stress. The aim of the work was to determine the cobalt chelating activity of a row of flavonoids using spectrofotometric measurements in vitro at 4 pathophysiologically relevant pH conditions (pH 4.5, 5.5, 6.8 and 7.5). Of the test substances, only 3-hydroxyflavon and baicalein showed chelation activity. 3-hydroxyflavon in a 1:1 ratio achieved 100 % chelation at pH 7.5 and about 60 % at pH 6.8. Baicalein was reactive at pH 7.5 and 6.8, when at 10:1 it was able to bind about 50...
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Search for an efficient cobalt chelator
Nosková, Karolína ; Mladěnka, Přemysl (advisor) ; Smutný, Tomáš (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Karolína Nosková Supervisor: prof. Přemysl Mladěnka, PharmD., Ph.D. Consultant: Monika Moravcová, MSc. Title of diploma thesis: Search for an efficient cobalt chelator Cobalt, as part of vitamin B12, is an essential trace element for human organism. However, long-term exposure to high doses leads to toxicity. Chronic cobalt intoxication is currently most commonly observed after the implantation of cobalt-containing prostheses, which in some cases do not work properly and cobalt is released from them by mechanical friction or corrosion. That not only leads to a local reaction, but cobalt ions also enter the blood and lymphatic circulation and thus cause a systemic reaction. The intoxication is then manifested by neurological, cardiovascular and endocrine symptoms, which can lead to irreversible changes or even to the death. However, a chelator that would be able to effectively and selectively bind cobalt and thus effectively treat intoxication is not available in clinical practice. The aim of this thesis was a search for an efficient cobalt chelator among known metal chelators. Chelation was measured in vitro by a method based on spectrophotometric detection of unchelated cobalt ions at...
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