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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Matematické transformace v dielektrické relaxační spektroskopii / Mathematical transformation in dielectric relaxation spectroscopy

Brida, Marek January 2011 (has links)
This labor treats the problem of dielectric relaxation spectroscopy in time domain, measurement of the absorption characteristics and their conversion to the frequency domain by creating a frequency depends of loss factor. Paper reports an overview of the most common mathematical transformation and approximation, which are used for this conversion and they also compare some of them. Mathematical methods used in this paper are Fourier transformation and Hamon approximation. Measured dielectric insulation is slot insulation type Isonom NKN 2039 and Isonom NMN 0967.
12

Studium defektů v kvazikrystalech metodou pozitronové anihilační spektroskopie / Studium defektů v kvazikrystalech metodou pozitronové anihilační spektroskopie

Vlček, Marián January 2011 (has links)
In the present work positron lifetime spectroscopy and coincidence spectroscopy of Doppler broadening of annihilation radiation were employed for investigations of defects in Mg alloys with icosahedral phase. Samples of WE43 alloy and WE43 alloy modified by addition of zinc were investigated. Positron trapping at vacancy-like defects associated with interface between the icosahedral phase Mg3Zn6Y1 and Mg matrix was observed. Investigations of MgZnAl-based alloys were performed as well. Vacancy-like defects were not detected in MgZnAl- based alloys by positron lifetime spectroscopy. However, coincidence spectroscopy of Doppler broadening of annihilation radiation revealed that positron trapping in the vincinity of icosahedral Mg44Zn41Al15 phase occurs. Several hypotheses ex- plaining different nature of positron trapping in WE43-based and MgZnAl-based alloys were proposed. Keywords: quasicrystals; positron annihilation spectroscopy; positron trapping; open-volume defects
13

Ramanova spektroskopie kapkově nanášených povlaků biologicky významných molekul / Drop coating deposition Raman spectroscopy of biologically important molecules

Kuižová, Alžbeta January 2019 (has links)
Drop coating deposition Raman (DCDR) spectroscopy is a special method of Raman spectroscopy, which is based on the evaporation of solvent from a drop of solution or suspension on a hydrophobic surface. This typically leads to the formation of ring-shaped drying pattern, often called as "coffee ring". As a result a preconcentration of a material and higher intensity of Raman signal in comparison with Raman scattering from solution is obtained. In this work several hydrophobic surfaces with different roughness and hydrophobicity were compared: a smooth substrate with polytetrafluorethylen (pPTFE) coating and nanorough substrates where surface hydrophobicity was formed by deposited cupper or argent nanoparticles with different concentration. It was shown that for DPPC liposome suspension stronger preconcentration is obtained by means of a nanorough substrate. When different nanorough substrate compared, no better improvement was acquired. As for the drying of drops at different temperatures (from 15řC to 60řC) deposited on the smooth pPTFE substrate and the substrate with argent nanoparticles, it was observed that Raman spectra did not reveal any spectral changes corresponding to phase transition of lipid. In case of drying at temperatures higher than a temperature of the phase transition, non-homogeneities...
14

Vlastnosti grafenoidových vrstev / Properties of graphenoid layers

Mach, Radoslav January 2018 (has links)
Master thesis “Properties of graphenoid layers” deals with materials of graphenoid nature such as graphene, graphene oxide and its reduced state. The paper effectively summarize basic theoretical knowledge in the first half of its range. In the second half the project deals with practical part consisted of experiments with application of graphene oxide solvents, its analysis and especially comparing properties of non-reduced graphene oxide with its chemically reduced form. Material is examined in a form of applied thin layers on different substrates.
15

Elektrochemické charakteristiky hořčíkových slitin AZ31 a AZ61 v Hankových roztocích / Electrochemical characteristics of AZ31 and AZ61 magnesium alloys in Hanks‘ solutions

Minda, Jozef January 2015 (has links)
This thesis deals with the characterization of electrochemical corrosion properties of magnesium alloys as promising materials for biomedical applications. The wrought alloys AZ31 and AZ61 were used and exposed to corrosive environments of Hanks solutions (SBF) to simulate environmental conditions in living organisms. For the evaluation of the surfaces was used scanning electron microscopy (SEM) with elemental analysis measured by energy-dispersive spectroscopy (EDS). Short-term (5 min) and long-term (72 h) corrosion tests were conducted in order to optimize the measurement methodology and obtain corrosion parameters - especially corrosion potential (Ekor), corrosion current density (ikor) and polarisation resistance (RP). To evaluation of the short-term tests were by potentiodynamic tests, namely the linear polarization (LP) test. Long-term tests were measured by electrochemical impedance spectroscopy (EIS). Effects of the composition of the alloys (AZ31 and AZ61), surface treatment (grinding and polishing) and the composition of the solution (SBF without Ca, Mg, and with Ca, Mg) were compared. Complex corrosion behaviour in time was characterized and corrosion mechanisms were discussed.
16

Regulace produkce lipidů a lipidických metabolitů u kvasinek / Regulation of production of lipids and lipid compounds in yeasts

Rapta, Marek January 2015 (has links)
Oleogenic yeasts under appropriate conditions produce and accumulate lipids and lipid-soluble metabolites in high amounts. This attribute is characteristic also for red yeasts that except lipids accumulate also carotenoids – natural pigments used in food industry and dietary supplements. The aim of this diploma thesis was designed as a comparative screening study of production properties of strains Cystofilobasidium capitatum, Rhodotorula glutinis, Sporobolomyces roseus and Sporobolomyces shibatanus. Choosen carbon sources were glucose and glycerol as waste by-product in biofuel industry. The best production properties were found in Cystofilobasidium capitatum and Rhodotorula glutinis. These two strains produced increased amounts of lipids as well as higher amounts of carotenoids. Strains were tested by FTIR spectroscopy that enables high-throughput, uncomplicated and accurate analysis.
17

Tenké vrstvy připravené v RF doutnavém výboji a jejich fyzikálně-chemické vlastnosti / Thin films prepared in RF glow discharge and their physico-chemical properties

Bránecký, Martin January 2015 (has links)
Theoretical part of this master thesis was focused on literature recherché dealing with the formation of thin films, plasma, plasma analyses using mass spectrometry and plasma polymerization. Further, this section describes the analysis of thin films using optical methods such as spectroscopic ellipsometry and FT-IR spectrometry. Experimental part describes the materials which are used for the preparation of thin films as well as a description of the equipment for preparation of thin films using a technology of plasma-enhanced chemical vapor deposition (PE-CVD). Control of deposition conditions and monitoring of plasma with its products result in high reproducibility of thin films. The last part of the thesis describes the results of measurement of the first group of samples and their ellipsometric, mass spectrometry and FT-IR evaluation with respect to the deposition conditions.
18

Optický systém pro torzně detekovanou elektronovou spinovou rezonanční spektroskopii / Optical setup for torque detected electron spin resonance spectroscopy

Kern, Michal January 2015 (has links)
Táto diplomová práca sa venuje vylepšeniu spektroskopu Torzne Detegovanej Elektrónovej Spinovej Rezonancie (TDESR) výmenou aktuálnej kapacitnej detekcie výchylky ohybného ramienka za optické metódy. Práca popisuje základy Elektrónovej Spinovej Rezonančnej (ESR) spektroskopie s dôrazom na TDESR a tému magnetizmu jednomolekulových magnetov. Následne je vysvetlená detekcia výchylky ramienka pomocou odrazu laserového zväzku a interferometrie. Všetky kroky nutné k skonštruovaniu spektrometra a jeho uvedenia do prevádzky sú podrobne popísané. Pomocou detekcie odrazu laserového zväzku sme úspešne získali vysoko kvalitné TDESR spektrá kryštálu jednomolekulového magnetu Fe4. Týmto meraním sme dokázali vhodnosť použitia tejto metódy a jej výraznú prevahu nad pôvodnou kapacitnou detekciou, najmä v oblasti kvality, rozlíšenia a rýchlosti. Zároveň sme na ďaľšie vylepšenie TDESR spektrometra navrhli a zostrojili zostavu využívajúcu na detekciu výchylky interferometer.
19

Studium rekombinace molekulárních iontů s elektrony v nízkoteplotním plazmatu pomocí Cavity Ring-Down Spektroskopie / Study of electron - molecular ion recombination in low temperature plasma using Cavity Ring-Down Spectroscopy

Kassayová, Miroslava January 2021 (has links)
The interactions of electrons with ions and ions with neutrals are among the most important processes in the chemical evolution of molecules, allowing us to gain a deeper understanding of chemical processes in low-temperature environments in space such as interstellar gas clouds and to obtain feedback for quantum-mechanical calculations. Vari- ous plasma parameters such as kinetic and rotational temperature of ions, their concen- tration, etc. can vary by several orders of magnitude and different diagnostic techniques are used to determine them. Diagnostics such as SA-CRDS and Cryo-CRDS were used in this work. The subject of the study were two molecular ions: N2H+ and N+ 2 from the temperature range of 80-350 K, where we examined their recombination and absorption rate coefficients utilizing the absorption line involving the most populated states. 1
20

Aprotické gelové elektrolyty s tetraalkylamonnými solemi / Gel aprotic electrolytes with tetraalkylamonium salts

Michalec, Juraj January 2019 (has links)
The essence of this graduate thesis is to summarize knowledge about the aprotic gel electrolytes. In the graduate thesis, there are explained methods for mensuration electrochemical properties of the aprotic gel electrolytes. In the theoretical part, I focus on the knowledge related to gel polymeric electrolytes, their history, properties, mechanisms and application. In the experimental part, I describe the preparation of the samples of the gel polymeric electrolytes, in which I evaluate their properties, electrical conductivity and potencial window.

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