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Possibilities of usage of electronic signature
Tomo, Milan ; Stejskal, Jaroslav (referee) ; Smejkal, Vladimír (advisor)
The bachelor thesis „Possibilities of usage of electronic signature“ proposes to give complete information about technology, laws and possibilities of usage of electronic signature. It clarifies principles of digital signature like symmetric, asymmetric cryptography, HASH function. It explains used terminology like certificate, certification authority, etc. It compares laws concerning electronic signature in Czech republic and in Slovakia. It provides guide to acquisition certificate and its installation. At the end shows possibilities of usage of electronic signature in practice.
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Materials combining conducting polymers and noble metals
Bober, Patrycja Magdalena ; Stejskal, Jaroslav (advisor) ; Omastová, Mária (referee) ; Pron, Adam (referee)
Polyaniline-silver composites combine the electrical properties of metals and the material properties of polymers. Polyaniline is one of the most studied conducting polymers on account of high electrical conductivity (units S cm-1 ), environmental stability, ease of preparation from common chemicals, good processibility and low cost. Silver is well known because of its highest conductivity among metals (500 000 S cm−1 ), antibacterial properties, and low price compared to other noble metals. Aniline was oxidized with silver nitrate in acidic aqueous medium to polyaniline-silver composite. The presence of different organic acids was studied. The most promising became methanesulfonic acid solution, in which most problems (such as inhomogeneity of samples and limited solubility of silver salts) got solved. The oxidation of aniline with silver nitrate is slow and takes over several months to get a reasonable yield. An addition of a small amount of p-phenylenediamine, even 1 mol. % relative to aniline, shortens the reaction time to several hours or even to tens of minutes. Small amounts of ammonium peroxydisulfate had similar effect. The content of silver in composites is fixed by the stoichiometry of reaction, and composites always contain ≈70 wt.% of silver. By using mixed oxidants, silver nitrate and...
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Materials containing conducting polymers
Blinova, Natalia ; Stejskal, Jaroslav (advisor) ; Pfleger, Jiří (referee) ; Žigon, Majda (referee)
l. Aims of the Thesis The goal of the Thesis is ůeprlaaraiior ..f .'a:ious norpho|ogies produced by conductingpoly.rners, riz. polvaniline (P{\Ji. the.-onrol of ce.n,tu.-:rrrl. a.rC the understanding of the chemistrv of aniline oxidatton. In rhese studies. three ditTerenr drrectiors have been developed. The first pan of the Thesrs rs focused on the slnthesrs of p.{NI. The oprrmum conditions for preparation of all forms available: powders, thin films, and colloidal dispersrons with respect to the morphology' ýeld, and conductiúý have been described. A systematic study of PANI protonated with phosphoric acid as well as a comparative study of the preparation of PANI and polypynole (PPy) have been made. The oxidation of aniline with noble-merals compounds, such as silver nitrate, the effect of the medium acidity, concentration of reacunts and the possible effect of daylight have been invesrigated. A new approach for the synthesis of PANI with separated reactants, aniline and an oxidant, is described in the second part of the Thesis. Various studies have been presented here to investigate the mechanisms of such reactions. The concept of coupled PANl-assisted redox reaction by means oftransport ofelectrons and protons through conducting PANI membrane has been demonstrated. A possible electron-ion-coupled...
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Anticorrosive properties of silicotungstic acid and phosphotungstic heteropolyacid in the paint films
Nechvílová, K. ; Kalendová, A. ; Stejskal, Jaroslav
The aim of this work was to provide an initial characterisation of heteropolyacids and examine their behaviour and properties as pigments in paints using different concentrations of the pigment and filler. Solvent-based epoxy-ester resin served as the binder. The paints were applied to steel and glass panels for mechanical and corrosion resistance testing. The organic coatings were exposed to a corrosive atmosphere with NaCl. This test was completed with electrochemical measurement. The parameters examined included the paint film's mechanical and anticorrosion efficiency. The environments in which the new coatings are most efficient were also sought.
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Materials combining conducting polymers and noble metals
Bober, Patrycja Magdalena ; Stejskal, Jaroslav (advisor) ; Omastová, Mária (referee) ; Pron, Adam (referee)
Polyaniline-silver composites combine the electrical properties of metals and the material properties of polymers. Polyaniline is one of the most studied conducting polymers on account of high electrical conductivity (units S cm-1 ), environmental stability, ease of preparation from common chemicals, good processibility and low cost. Silver is well known because of its highest conductivity among metals (500 000 S cm−1 ), antibacterial properties, and low price compared to other noble metals. Aniline was oxidized with silver nitrate in acidic aqueous medium to polyaniline-silver composite. The presence of different organic acids was studied. The most promising became methanesulfonic acid solution, in which most problems (such as inhomogeneity of samples and limited solubility of silver salts) got solved. The oxidation of aniline with silver nitrate is slow and takes over several months to get a reasonable yield. An addition of a small amount of p-phenylenediamine, even 1 mol. % relative to aniline, shortens the reaction time to several hours or even to tens of minutes. Small amounts of ammonium peroxydisulfate had similar effect. The content of silver in composites is fixed by the stoichiometry of reaction, and composites always contain ≈70 wt.% of silver. By using mixed oxidants, silver nitrate and...
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Materials containing conducting polymers
Blinova, Natalia ; Stejskal, Jaroslav (advisor) ; Pfleger, Jiří (referee) ; Žigon, Majda (referee)
l. Aims of the Thesis The goal of the Thesis is ůeprlaaraiior ..f .'a:ious norpho|ogies produced by conductingpoly.rners, riz. polvaniline (P{\Ji. the.-onrol of ce.n,tu.-:rrrl. a.rC the understanding of the chemistrv of aniline oxidatton. In rhese studies. three ditTerenr drrectiors have been developed. The first pan of the Thesrs rs focused on the slnthesrs of p.{NI. The oprrmum conditions for preparation of all forms available: powders, thin films, and colloidal dispersrons with respect to the morphology' ýeld, and conductiúý have been described. A systematic study of PANI protonated with phosphoric acid as well as a comparative study of the preparation of PANI and polypynole (PPy) have been made. The oxidation of aniline with noble-merals compounds, such as silver nitrate, the effect of the medium acidity, concentration of reacunts and the possible effect of daylight have been invesrigated. A new approach for the synthesis of PANI with separated reactants, aniline and an oxidant, is described in the second part of the Thesis. Various studies have been presented here to investigate the mechanisms of such reactions. The concept of coupled PANl-assisted redox reaction by means oftransport ofelectrons and protons through conducting PANI membrane has been demonstrated. A possible electron-ion-coupled...
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Nanostructures produced by conducting polymer, polyaniline
Konyushenko, Elena ; Stejskal, Jaroslav (advisor) ; Vohlídal, Jiří (referee) ; Žigon, Majda (referee)
Charles University in Prague Faculty of Science Department of Physical and Macromolecular Chemistry Institute of Macromolecular Chemistry Academy of Sciences of the Czech Republic Nanostructures produced by conducting polymer, polyaniline Abstract of the Doctoral Thesis Elena Konyushenko Supervisor: Jaroslav Stejskal, PhD. Prague 2008 Univerzita Karlova v Praze Přírodovědecká fakulta Katedra fyzikální a makromolekulární chemie Ústav makromolekulární chemie Akademie věd České republiky, v.v.i. Nanostruktury vytvářené vodivým polymerem, polyanilinem Autoreferát disertační práce Ing. Elena Konyushenko Školitel: RNDr. Jaroslav Stejskal, CSc. Praha 2008 Contents 1. The aims of the Thesis 5 2. Preparation of polyaniline 6 3. Polymerization of aniline in the solutions of weak acids 7 4. Oxidation of aniline in alkaline media 8 5. Supramolecular morphology of polyaniline 9 6. Preparation of composites of carbon nanotubes and polyaniline 15 6.1. Carbon nanotubes coated by polyaniline 15 6.2. Properties of the composites 15 7. Carbon nanotubes with nickel catalyst nanoparticles coated by polyaniline 16 Abstract (in Czech) 18 References 19 List of papers 21 4 List of papers 1. Konyushenko EN, Stejskal J, Šeděnková I, Trchová M, Sapurina I, Cieslar M, Proke J, Polyaniline nanotubes: conditions of formation, POLYMER...
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Possibilities of usage of electronic signature
Tomo, Milan ; Stejskal, Jaroslav (referee) ; Smejkal, Vladimír (advisor)
The bachelor thesis „Possibilities of usage of electronic signature“ proposes to give complete information about technology, laws and possibilities of usage of electronic signature. It clarifies principles of digital signature like symmetric, asymmetric cryptography, HASH function. It explains used terminology like certificate, certification authority, etc. It compares laws concerning electronic signature in Czech republic and in Slovakia. It provides guide to acquisition certificate and its installation. At the end shows possibilities of usage of electronic signature in practice.
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