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Proposal of Part of Company Information System
Březina, Václav ; Strýčková, Jitka (referee) ; Luhan, Jan (advisor)
This bachelor thesis solves the design of section of information system for company ABB s. r. o. In the first part of thesis, I will deal with theoretical formulation of basic concepts. Next part objective is analysis of current state of the company and creation of information system. The goal of the thesis is to create database and web interface of the IS.
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Investigation of the Properties of Novel Contrast Agents for Magnetic Resonance Imaging
Plšek, Martin ; Římal, Václav (advisor) ; Březina, Václav (referee)
Abstract: Contrast agents for magnetic resonance imaging frequently employ organic com- plexes of paramagnetic ions. The present work studies rotation of phoshonate group in LnIII complexes of monoethylester-P of 1,4,7,10-tetraazacyclododecane-4,7,10-tris(karboxyme- thyl)-1-methylphosphonic acid (Lndo3apOEt ), specifically Lado3apOEt and Cedo3apOEt . 31 P and 1 H NMR spectra were measured in a wide temperature range. Transverse relaxation times and chemical shifts of the two 31 P spectral lines which undergo mutual chemical exchange were estimated. The phosphorus spectra were then subjected to line-shape analysis, thus cha- racterizing the chemical exchange connected to phosphonate rotation. This process yielded temperature dependence of both rate coefficients and relative populations between the two di- astereoisomers for both studied molecules. The termodynamic parameters were obtained and compared with similar complexes with phosphonate rotation. The knowledge of the detailed kinetics can later lead to improvements of the efficiency of the contrast agents. Keywords: nuclear magnetic resonance, MRI contrast agent, kinetics of conformational ex- change
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Supramolecular complexes of oxoporphyrinogens with organic molecules
Březina, Václav ; Hanyková, Lenka (advisor) ; Mojzeš, Peter (referee) ; Tošner, Zdeněk (referee)
Title: Supramolecular complexes of oxoporphyrinogens with organic molecules Author: Václav Březina Department: Department of Macromolecular Physics Supervisor: doc. RNDr. Lenka Hanyková, Dr., Department of Macromolecular Physics Abstract: Oxoporphyrinogens are flat macrocyclic molecules possessing binding and protonation sites, and capable of light absorption in the visible region. These properties are prerequisites for a colori- metric molecular sensor, i.e. a specific detector of other molecules in the sample. In this work, we studied chromic properties of three oxoporphyrinogens, OxP and its partially (Bz2OxP) and fully (Bz4OxP) N-benzylated derivatives. Their colorimetric response to organic acids is caused by protonation and subsequent formation of supramolecular host-guest complex. We have shown that colorimetric sensitivity is highest for OxP and gradually weakens for Bz2OxP and Bz4OxP since the N-benzylation blocks the central binding sites, decreasing binding affinity of the ox- oporphyrinogens. Furthermore, solvatochromic response of the oxoporphyrinogens to varying solvent polarity showed similar sensitivity decrease in Bz2OxP and Bz4OxP. The chromic and binding properties were studied by UV/vis and NMR spectroscopy, host-guest binding models were applied to describe the formation of...
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A contrastive description of English and Czech using the methodology of n-gram extraction
Šebestová, Denisa ; Malá, Markéta (advisor) ; Březina, Václav (referee) ; Kopřivová, Marie (referee)
This dissertation examines phraseological patterns in three registers (parliamentary debates, newspaper reporting, children's fiction) in English and Czech. It identifies and analyses recurrent word sequences through n-gram extraction, aiming to characterise the phraseology of each register and compare them cross- linguistically, while observing how the n-gram method can be adapted to accommodate for the typological properties of each language. Czech is particularly challenging in this respect due to its morphological and positional variability. The dissertation comprises three case studies, each focussed on a different register. The first case study explores different n-gram lengths using a small corpus of a specialised register - parliamentary debates, suggesting that for a comprehensive register characterisation, different lengths should be combined. It notes the importance of discourse-structuring patterns and the problem of overlaps between n-grams. In the newspaper study, I extract n-grams containing prepositions - a convenient starting point given their frequency and involvement in text- structuring. N-grams are complemented with collocation analysis, revealing some evaluative prosodies and semantic preferences of patterns and suggesting that the newspaper register is not purely...
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Material design problems of plasma-chemical reactors for disposal perfluorinated compounds
Brožek, Vlastimil ; Březina, Václav ; Mastný, L. ; Kubatík, Tomáš František ; Živný, Oldřich
Reduction of perfluorinated gases emissions from semiconductor industry has recently introduced a serious problem from both technological and economic side. With respect to chemistry of the decomposition reactions the most effective abatement techniques developed up to now consists in the interaction of those gaseous pollutants with several types of plasmas. In the framework of Czech-Taiwanese bilateral project No. 17-10246J 'Decomposition of Perfluorinated Compounds and Fluorinated Ozone Depleting Substances' a new plasmochemical reactor design is to be solved. In this reactor the plasma abatement process consisting of interaction of the plasma generated by unique watter stabilized H-WSP plasma torch at temperatures ranging\nfrom 2000 K up to 25,000 K with the treated gases will be carried out. However, the main product generated in the reactor during the steam plasma abatement process is hydrogen fluoride which causes corrosion of almost every construction material. The aim pursued by the work presented is to search for the materials resistant to exposition of HF even at high temperatures. To investigate corrosion resistance of construction materials with thermal stability within temperature interval 2700-3000 °C titan nitride, boron nitride, and silicon carbide have been selected. The samples of those materials have been prepared by spark plasma sintering method and exposed to concentrated solution of hydrofluoric acid for which corrosion rates have been measured
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Spektroskopické a teoretické studium supramolekulárních komplexů symetrických porfyrinů s chirálními guesty
Březina, Václav ; Hanyková, Lenka (advisor) ; Šoltésová, Mária (referee)
Certain types of porphyrins can be used as achiral agent for determination of enantiomeric excess (ee) of chiral molecules. Particular organic chiral molecule (guest) and porphyrin (host) form host-guest complex while inducing nonequiv- alency of particular proton resonances in symmetrical host. It causes splitting of NMR signals linearly dependent on ee of guest. In this work we investigated com- plexation of di-brombenzylated oxoporphyrin with chiral camphorsulfonic acid. NMR titration revealed that they form complex with 1:1 stoichiometry with as- sociation constant K ≈ 5 × 104 l/mol. We confirmed linear dependence of split- ting of host β-protons on ee of guest. Low temperature measurements revealed two conformations of host-guest complex with population around 0.7:0.3 (at −60 ◦ C). DFT quantum mechanical computations at BLYP/3-21G* level revealed also two conformations with population 0.79:0.21. NMR shifts were computed on this geometries with method GIAO/PBE1PBE/6-31G(2df,2pd) and compared to experimental values. 1
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Photocatalytic Decomposition of Wastewater from the Production of Explosives
Brom, Petr ; Brožek, Vlastimil ; Březina, Václav ; Hlína, Michal ; Mastný, L. ; Novák, M.
Water stabilized plasma generator WSP® H-500, operating on the principle of Gerdien arc was used for the photocatalytic decomposition of furazan- and picraminate-based explosives. The generator emits intensive radiation in the range of 300-660 nm, which allows not only to activate photocatalysts based on TiO2, but also other semiconductor oxides with a narrower band gap, such as tungsten oxide. The photocatalytic decomposition of sewage and slurries containing the potassium salt of 4-hydroxy-4,6-dihydro-5,7- dinitrobenzofurazane-3-oxide (KDNBF) or sodium picraminate (NaC6H4N3O5) was performed using the anatase paste and newly developed photocatalyst produced by the company Precheza a.s. The photocatalytic reactor was built using a quartz tube coil with an internal volume of 650 ml, with a nominal size of the irradiated area of 7.5 dm2 (value reduced by the area of the gaps between coil turns) to enable the flow the processing solution or suspension of up to 10 l / min. The centre of the coil is exposed to the plasma jet with the intensity\nof 80 kW; of which 15 kW is transformed into the light radiation. 11% of the radiation output was used for the presented experiments. The time of exposition was 45 mins and 20 l of solution were treated. In the case of KDNBF, 90% of the compound was decomposed. Moreover, 100% of sodium picraminate were decomposed after 15 minutes into low-molecular inorganic compounds. Advantage of the assembly is the ability to treat highly dangerous chemical compounds in a closed cycle and test selective catalyst
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Black Chromia Plating for the Solar Radiation Absorbers
Brožek, Vlastimil ; Březina, Václav ; Brom, Petr ; Kubatík, Tomáš František ; Vilémová, Monika ; Mastný, L. ; Novák, M.
Black chromia layers were produced on copper, zirconium and aluminium substrates. These layers are aimed to serve as solar collectors. Efficiency of the layers during UV-VIS, UV radiation and WSP® plasma torch radiation is described. The chromia layers were prepared by a new procedure, i.e. deposition of ammonium dichromate solution using plasma torch or so called Liquid Precursor Plasma Spraying (LPPS). Solution of ammonium dichromate is fed into plasma stream, where dissociation takes place under temperatures of 4000 K – 25000 K. Up to nanometric oxide particles can be produced; the resulting size is dependent on solution concentration and feeding nozzle diameter. The particles impact on substrate and form coating. Using 2 wt.% to 5 wt.% solution of ammonium dichromate and feeding nozzle of 0.2 mm in diameter is the size of produced chromia particles about 6 µm which results in formation of 2 µm to 3 µm thick coating, i.e. according to the theory an optimal thickness 2.5 um for absorption layers, necessary condition for formation energy traps for IR radiation emitters up to 100°C. Moreover, black chromia coating is a suitable corrosion barrier of metallic substrates. \n\n
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