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List of available PhD theses

"Transparent ceramics for optical applications synthetized by pressure- or vacuum-assisted sintering methods

Department: Department of Inorganic Chemistry, Faculty of Chemical Technology

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Transparent ceramics can compete with single crystalline materials not only in the stage of research and development but also in the final application. The thesis will be focused on the synthesis of oxide ceramics applicable in the laser or LED field, or utilizable at the detection of ionizing radiation. Spark plasma sintering (SPS) or vacuum sintering will be used for the processing of precursor powders whose optimal crystallinity and microstructure will be also the task of the thesis.

Elucidating the origin of magnetoelectric coupling in Fe4M2O9 phases

Department: Department of Inorganic Chemistry, Faculty of Chemical Technology

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Multiferroic materials exhibiting at least two ferroic orders such as ferroelectricity and ferromagnetism are the focus of researchers attention. The magneto-electric coupling is very appealing for applications in devices, such as memories, where the magnetic information has to be controlled by an electric field. The thesis work will focus on the synthesis and the study of the structural/magnetic/dielectric/ ferroelectric properties of Fe4M2O9 mono- and poly-crystals. As these Fe2+ containing oxides exist only for M = Nb and Ta, the thermodynamic stability of these phases will be calculated in connection with their magneto-elastic coupling.

Exploration of the Fe-W-O system for magnetism and photo(electro) chemistry

Department: Department of Inorganic Chemistry, Faculty of Chemical Technology

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The aim of this study is to capitalize on the richness of the crystalline, magnetic and electronic structures and photocatalytic properties of W-based oxides by investigating the Fe-W-O system. It is proposed to focus on Fe2WO6 as it crystallizes in three different structures exhibiting different transport and magnetic properties. It is of interest to study the thermodynamic conditions in this area of the ternary diagram Fe-W-O to monitor and optimize precise composition and synthesis conditions. Structures and microstructures will be studied by suitable diffraction methods and microscopies. Compounds will be characterized by measuring their magnetic and electrical properties; those with suitable bandgap will also be tested for photocatalytic or photoelectrochemical properties relevant to catalytic degradation of organic pollutants, water splitting or photovoltaic cells.

Galvanic electrocatalytic layers in water alkali electrolysis

Department: Department of Inorganic Technology, Faculty of Chemical Technology
Theses supervisor: Ing. Jaromír Hnát, Ph.D.

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The aim of this project is development of an efficient electrocatlyst for cathodic hydrogen evolution reaction (HER) in an alkaline environement based on galvanic modification of the Ni substrate. After identification of the optimal coatings properties and deposition method the techniques will be transferred to the 3D porous electrodes to enhance process efficiency and tested in a laboratory and pilot scale alkaline water electrolysis cell.

Gas - Liquid Mass Transfer. Experimental comparison of various apparatuses performance.

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: prof. Dr. Ing. Tomáš Moucha

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The volumetric mass transfer coefficient (kLa) plays a crucial role in industrial design in the case of the process controlled by gas–liquid mass transfer. Prediction of kLa is nowadays mostly based on literature correlations. Our research goal is to establish suitable kLa correlations for different types of devices that would be based on the experimental dataset. The PhD thesis aim at the comparison of various gas-liquid contactor types from the viewpoint of their mass transfer efficiency. The suitable correlations will be developed that would be viable for mechanically agitated gas–liquid contactors and also for pneumatically agitated gas–liquid contactors such as airlift reactor.

High-entropy alloys prepared by powder metallurgy techniques

Department: Department of Metals and Corrosion Engineering, Faculty of Chemical Technology
Theses supervisor: Ing. Filip Průša, Ph.D.

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Since the year 2004, the materials research gained a new way of focusing on special alloys made initially of five elements with equiatomic compositions. The newly discovered group of materials has been since then known as high-entropy alloys (HEA) due to a high entropy of mixing which allows creating predominantly solid solutions instead of intermetallic phases. These materials are known to be exhibiting a variety of excellent properties that often combine high strengths while maintaining good ductility, good corrosion resistance and others.
The work will aim at the description of the microstructure-related properties of high-entropy alloys prepared by powder metallurgy techniques combining mechanical alloying and compaction via spark plasma sintering.

Impact of the magnetism on the thermoelectric properties of oxides and sulfides

Department: Department of Inorganic Chemistry, Faculty of Chemical Technology

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Thermopower can be very sensitive to spins and magnetism, and its enhancement has already been observed in oxides, as exemplified in NaxCoO2 or in misfit cobaltites. Recently, the impact of magnetism has been evidenced in ferromagnetic and metallic CoS2 with an extra contribution to thermopower measured in the. In the insulating thiospinel CuCrTiS4, the transport properties are actually very similar to magnetoresistant oxides, with variable range hopping transport associated to a large negative magnetoresistance and magnetothermopower. The aim of this project is to investigate the influence of magnetism on the thermoelectric properties of these sulfides presenting different ground states, to tune and optimize this enhancement of thermopower. A detailed investigation of the thermal properties will also be realized.

Interpretation of Raman optical activity of nucleic acids

Department: Department of Analytical Chemistry, Faculty of Chemical Engineering
Study programme: Chemie (double degree)
Theses supervisor: prof. RNDr. Petr Bouř, CSc.

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Spectroscopy of vibrational Raman optical activity is a new and dynamically evolving analytical method providing important information, such as about biopolymer and enzyme structure. The applications are very dependent on spectral interpretations based on the molecular dynamics and quantum chemical computational methods. For nucleic acids, although experimentally very interesting systems can be approached, including viruses, the relation between the spectrum and the structure is not completely known. A big problem are computer demands required by these complex and big molecules. We will therefore focus on development of experimental and computational methodology for model system, suitable to describe specific nucleic acid properties, such as flexibility and polarity. Modern computational methods will be both used and developed, such as combination of classical and quantum mechanics or testing models of solvent and environment during molecular interactions.

KLa - shear stress coupling to design fermenters better

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: prof. Dr. Ing. Tomáš Moucha

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In fermentation technologies, mechanically agitated aerated vessels are frequently used. In cases of aerobic fermentations, the Oxygen Uptake Rate - OUR is frequently used as the important design parameter. This means that the gas-liquid mass transfer controlled process is considered and the volumetric mass transfer coefficient - kLa is taken as the most important parameter. The practice shows, however, that the impellers with lower Power number (which means lower turbulence intensity and lower kLa) often ensure higher bioprocess efficiency than those with high Power number (which means higher turbulence intensity and higher kLa). The explanation is brought by the fact that microorganisms/biomass might be damaged by the high turbulence intensity as explained further. The turbulence intensity is proportional to shear stresses occuring in the mechanically agitated fermentation batch. A high shear stress may "cut" the microorganisms, which stop producing their primary product then. The aim of the PhD thesis is to measure the quantities proportional to shear stress values at the process conditions of aerobic fermentations and couple them with the kLa values, which are already at disposal in the Mass Transfer Lab database at UCT Prague. This data coupling will enable to develope the highly efficient industrial fermenters design tool.

Mechanism of the formation of intermetallics in mechanical alloying

Department: Department of Metals and Corrosion Engineering, Faculty of Chemical Technology
Theses supervisor: doc. Ing. Pavel Novák, Ph.D.

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Mechanical alloying is a popular technology for the preparation of powders of alloys or intermediary compounds (e.g. intermetallics, carbides or borides) by high energy mechanical milling. The high popularity of the method is given by the fact that it usually leads to nanostructured materials and that even non-miscible elements can create solid solutions during mechanical alloying. Even though the result is known and there are many descriptions available, the mechanism of the formation of intermetallics in this process is not fully understood yet. The reasons are probably in a large variety of possible process parameters and by impossibility to measure the temperature inside the powder in the milling jar. This work proposes following concept: indirect determination of the dependence of the peak powder temperature on milling conditions (rpm, ball-to-powder ratio, ball size) by the use of thermally decomposing salts, comparison of phase composition of the mechanically alloyed powder with the reference powder mixture exposed in the furnace to the detected peak temperature and observation of the time development of the microstructure and phase composition by XRD and electron microscopy (SEM, TEM). The mechanism will be observed on several different systems containing brittle and ductile powders (e.g. Ti-Al, Ti-Si, Ti-Al-Si) and the general conclusion regarding the mechanical alloying mechanism will be formulated.

Misfit cobaltites for high-temperature thermoelectric conversion – the role of phase composition and oxygen stoichiometry

Department: Department of Inorganic Chemistry, Faculty of Chemical Technology

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The aim of this work is the synthesis and characterization of cobalt mixed oxides, thermodynamic data measurement and assessments in the Bi-Ca-Co-O, Ca-Co-O and Bi-Sr-Co-O systems. Measurement of thermoelectric properties of the Bi1.8(Ca/Sr)2Co1.85Oz misfit phase including their dependence on variable oxygen stoichiometry as a function of temperature and oxygen activity will be also studied.

Nanostructured ferrited doped with magnetic elements to enhance their magnetocaloric effect

Department: Department of Inorganic Chemistry, Faculty of Chemical Technology
Theses supervisor: Ing. Ladislav Nádherný, Ph.D.

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Magnetic refrigeration is a modern and ecologic cooling technology based on the magnetocaloric effect (MCE). This technique can be used to attain extremely low temperatures, as well as the ranges used in common refrigerators. The main aim of this thesis is to enhance the magnetocaloric effect in FeCo ferrites by nanosizing and doping with magnetic ions, which both can affect magnetic phase transition near room temperature. Studied materials will be prepared by wet-chemistry methods (e.g. sol-gel, co-precipitation) and MCE will be characterized in PPMS in which the heat capacity will be measured in a strong magnetic field.

New effective separation membranes for water and wastewater treatment based on hybrid carbon-based materials

Department: Department of Physical Chemistry, Faculty of Chemical Engineering
Theses supervisor: doc. Ing. Karel Friess, Ph.D.

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Current membrane separation processes allow efficient purification and physical disinfection of water from undesirable components on the basis of a size-sieving mechanism without the need for chemical agents. The pore sizes and their distribution on the membrane surface is an important factor for the effective removal of contaminants and microorganisms. The thesis will study the possibilities of using newly prepared membrane materials based on carbon materials (carbon nanotubes, graphene derivatives, etc.) with targeted surface modifications (eg doping with antimicrobial agents, etc.) in order to effectively remove collected contaminants from water. In addition to the preparation, characterization and testing of materials, the work will also include modelling of the separation process. The result of this work will be, besides the preparation of an effective separation material and describing the model, an extension of knowledge in the given membrane field.

Non-Traditional Yeasts with Potential to Produce Special Fermented Beverages

Department: Department of Biotechnology, Faculty of Food and Biochemical Technology

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Today's beer market is very diverse and all producers are looking for ways to differentiate themselves. The aim of this work will be to find such yeasts that could be used for fermentation and at the same time provide an interesting and unique aroma of the final product in comparison with normal fermented beer. A secondary goal will be the search for a strain of microorganisms usable for the production of non-alcoholic beer.

Optimization of Electrochemical Ferrates(VI) Synthesis

Department: Department of Inorganic Technology, Faculty of Chemical Technology

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The aim of this project is characterization of chemical and electrochemical oxidation processes taking place at the surface of an anode made of iron based materials in strongly alkaline solutions. Deeper understanding of mechanism of these processes allows to enhance efficiency of synthesis of Ferrate (VI) making it economically viable.

Polymer-based membranes for highly selective removal of CO2 from biogas

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: doc. Ing. Petr Kočí, Ph.D.

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Membrane-based gas separation technology has contributed significantly to the development of energy-efficient systems for natural gas purification. Also CO2 removal from biogas, with CO2 contents exceeding 40% has more recently known rapid growth and development. Major challenge of polymer membranes for gas separation is related to their susceptibility to plasticization at high CO2 partial pressures. CO2 excessively swells the polymer and eases the permeation of CH4, thus reducing the selectivity. Membrane crosslinking is one of the best ways to prevent the plasticization. Mixed matrix membranes (MMMs), consisting of fillers homogeneously dispersed in a polymeric matrix aim at combining the processibility of polymers and the superior separation properties of the porous fillers. Metal-organic frameworks (MOFs) are such materials which have attracted considerable attention due to their tailorable functionality, well-defined pore size, pore tunability and breathing effects. MMMs for biogas upgrading will be prepared with increased permeabilities by choosing proper MOF/polymer combinations and modifying the thermal treatment, employing core-shell MOF materials with high bulk porosity and a selective shell layer.

Preparation of olefin block copolymers

Department: Department of Polymers, Faculty of Chemical Technology
Theses supervisor: doc. Ing. Jan Merna, Ph.D.

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The thesis will be focused on the preparation of block copolymers based on olefin and diene monomers by coordination copolymerizations. The focus will be on copolymers with blocks of different properties, e.g. hard and soft blocks. Principles of coordination chain transfer polymerization and chain-shuttling polymerization will be applied. Introduction of polar functional groups will also be of interest. The work will include organometallic synthesis of catalysts, polymerization experiments in presence of various transfer agents and full characterization of obtained polymers.

Production of antibacterial peptides from marine organisms and evaluation of their biological activity

Department: Department of Biochemistry and Microbiology, Faculty of Food and Biochemical Technology
Theses supervisor: prof. Ing. Tomáš Ruml, CSc.

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Design of bacterial expression system for production of existing antibacterial peptides identified in the laboratory of prof. Stensvåg at University in Tromso. Firstly, it is necessary to overcome the toxicity issues either by fusion with bulky protein or secretion achieved by fusion of the peptides to export sequence. Next step is upscale to massive production and purification for functional studies (pull down assay with bacterial cell lysate). Isolated products will be used for analysis of biological activity targeted against bacterial and yeast cells, including biofilms and determination of immunomodulatory effects. Subsequently it is planned a study of mechanisms leading to inhibition.

Příprava slitin na bázi Al se slitinami z hlubokomořských přírodních zdrojů a jejich korozní odolnost

Department: Department of Metals and Corrosion Engineering, Faculty of Chemical Technology

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Deep sea manganese nodules are formed by Mn and Fe oxide/hydroxides with minor amounts of critical elements like transition metals (TM) and rare earth metals (RE). The traditional way of processing this natural source is to separate the individual metals. This work is focused on innovative strategy of deep sea nodules utilization: a rough metallic alloy will be obtained by their reduction of natural mineral sources and it can be used for production of Al-based alloys. These alloys will be prepared by casting and extrusion with subsequent processing by rapid solidification and mechanical alloying, followed by spark plasma sintering compaction. Their microstructure and chemical-physics properties will be characterized and compared to commercial Al-alloys, which are widely used for different technological and industrial applications, due to their lightness, good mechanical properties and their low cost. Furthermore, considering all these applications, these metallic materials have a great interest in terms of corrosion performances in critical exposure conditions, therefore these studies will be performed as well.

Solvent and pH stable membranes with ultra-sharp molecular weight cut-off values

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: doc. Ing. Petr Kočí, Ph.D.

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Membrane-based separations currently offer the best strategy to decrease energy requirements and environmental footprint through newly developed solvent resistant nanofiltration (SRNF) or solvent-tolerant nanofiltration (STNF). So-called solvent activation of polymeric membranes involves treatment of an existing membrane by contacting it with solvents or solvent mixtures, which is hypothesized to restructure the membrane polymer through solvatation, increase polymer chain flexibility and organization into suitable structures. This will be verified by systematically treating membranes with different solvents and testing them for the separation of synthetic liquid streams. A high-throughput set-up will be used. Fundamental physico-chemical characterisations of the membranes before and after the treatments will provide insight in the changes at molecular level. The characterization techniques include gas and liquid uptake experiments (diffusivity), PALS (positron annihilation lifetime spectroscopy, to determine free volume element distributions), ERD (elastic recoil scattering, providing elemental analysis in membrane depth profiles), solid state NMR (nuclear magnetic resonance), TGA (thermogravimetric analysis) and DSC (differential scanning calorimetry).

Structural, Magnetic and Thermoelectric Properties of TM in ZnO / ZnS: Effects of Nano-sizing

Department: Department of Inorganic Chemistry, Faculty of Chemical Technology
Theses supervisor: Ing. Ladislav Nádherný, Ph.D.

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In the past ten years, the interest in zinc oxide research in the field of magnetic semiconductors has significantly increased. According to the Zener model, manganese-doped ZnO is one of the systems in which ferromagnetic behavior could be achieved even at room temperature. Since the solubility of magnetic Mn in bulk ZnO is very limited, new approaches to prepare thin films and nanoparticles with higher dopant concentration are used. The aim of this dissertation thesis is to prepare nanopowders based on ZnO with the highest concentration of Mn as possible. Prepared powders will be characterized by means of XRD, TEM, DSC, DLS, PPMS, and the nanosizing effect on the Mn solubility in ZnO or ZnS will be described.

Supramolecular assemblies and gels from helicene-polypeptide conjugates: synthesis and chiroptical properties

Department: Department of Analytical Chemistry, Faculty of Chemical Engineering
Study programme: Chemie (double degree)

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This work will be focused on the preparation and characterization of new supramolecular systems based on helicene-polypeptide conjugates. The polypeptide moiety will be systematically modified to produce highly ordered supramolecular aggregates stabilized by hydrogen and other interactions. Common methods of structural analysis including highly sensitive methods of chiroptical spectroscopy (electronic circular dichroism ECD, vibrational circular dichroism VCD and Raman optical activity ROA) will be used for the characterization.

System for remote monitoring of grey water reuse

Department: Department of Water Technology and Environmental Engineering, Faculty of Environmental Technology
Theses supervisor: doc. Ing. Jan Bartáček, Ph.D.

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One of the main obstacles to the use of treated gray water (i.e. water from bathrooms or washing machines) is the missing method for automatic detection of contamination in the treated waste water. As a result, it is not possible to use recycled water where there is a higher risk of end users exposure to the water contaminated with pathogens (e.g. washing machines, cleaning floors etc.).
In this project, we will develop an early warning system that will automatically detect disturbances in gray water treatment technology and especially the penetration of pathogenic organisms into the recovered water.

Tailoring of nanostructure in mixed matrix membranes for selective removal of CO2 from biogas

Department: Department of Physical Chemistry, Faculty of Chemical Engineering
Theses supervisor: doc. Ing. Karel Friess, Ph.D.

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Membrane separation processes belong to modern technologically important separation methods, which are less demanding (economically and ecologically) in comparison with classical separation methods. For the gas separation applications, mainly polymer membranes are used. Their performance (permeability or separation effect) can be additionally adjusted by the targeted embedding of liquid or solid additives into the polymer matrix. The dissertation thesis will focus on the preparation, characterization, and testing of the so-called mixed matrix membranes for the separation of gases based on glassy polymers and functional nano-additives with a purposefully prepared structure. In addition, modeling of the separation process will be part of the work. The result of this work will be prepared and tested membrane material for the effective removal of CO2 from biogas and extension of knowledge in the given membrane field.

Transparent ceramics for optical applications synthetized by pressure- or vacuum-assisted sintering methods

Department: Department of Inorganic Chemistry, Faculty of Chemical Technology
Study programme: Chemistry (double degree)

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Transparent ceramics can compete with single crystalline materials not only in the stage of research and development but also in the final application. The thesis will be focused on the synthesis of oxide ceramics applicable in the laser or LED field, or utilizable at the detection of ionizing radiation. Spark plasma sintering (SPS) or vacuum sintering will be used for the processing of precursor powders whose optimal crystallinity and microstructure will be also the task of the thesis.

Updated: 18.2.2020 13:59, Author: Jan Kříž

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