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Department of Chemical Engineering

List of available PhD theses

Advanced formulation approaches for topical delivery

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Although skin appears to be a macroscopically homogeneous and biologically passive structure, it is exactly the opposite: it is incredibly heterogeneous both chemically and structurally, and it is host to a diversity of active cells such as macrophages and bacteria. Traditional approaches to topical delivery have relied on relatively simple systems such as passive diffusion from water- or oil-based solutions or creams/gels. The aim of this project is to investigate bioactive transport as a mechanism for topical delivery and find a solution to such molecules as therapeutic peptides, which are known to be extremely challenging to formulate and delivery to the body. This project will explore the use of drug delivery systems that are actively phagocytised for targeting macrophages residing in the skin. These drug delivery systems will include naturally sourced polysaccharide shells or lipidic vesicles obtained from single-cell organisms. Their mild immunogenicity, biocompatibility and ability to encapsulate a broad range of molecules will be utilized for the formulation of APIs that have proven to be challenging by traditional means.

Application of microreactors for study and optimization of reactions in field of fine chemicals and pharmaceuticals

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

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Microreactors presents devices with small internal dimensions providing unique features for precise chemical processes control. These features are often employed for continuous processes control in field of fine chemicals and pharmaceuticals, where high product quality is required. Despite the high potential for improvement by synthesis in flow, the batch processes still prevail in industry. This thesis proposal therefore aims at the microreactor technology application, adaptation an optimization for continuous synthesis of fine chemicals and pharmaceutical components. The candidate should have a good knowledge of chemical and reaction engineering, organic chemistry and has good relation to experimental laboratory work to become familiar with microreactor technology, as well as with data acquisition and evaluation systems. To complete the delegated tasks, the personal abilities such as independence, creativity, open mind and team work skills will be required.

Application of molecular modelling in the screening and characterization of new solid forms of drug substances

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Experimental screening of new solid forms of drug substances, i.e. polymorphs, salts, co-crystals or solvates, is very labor process requiring of testing various conditions. Once the new solid form is discovered it is analyzed by a combination of several techniques including XRD, NMR, Raman spectroscopy, SEM, DSC, solubility and stability. In this project we plan to utilize molecular simulations to support experimental screening procedure. This will increase our fundamental understanding of involved interactions between drug and excipient molecules. In particular, we plan to use molecular modelling in the calculation of the interaction energies of prepared drug solid form to rank relative thermodynamic stability and melting temperature. When possible, molecular dynamics simulation will be benchmarked to experimentally measured properties of drug solid forms, i.e. XRD data, or to interactions determined by NMR or FTIR. In the last part, we plan to apply molecular modelling in the description of solubility of newly discovered solid forms in the presence of various excipients (i.e. surfactants, polymers, partner molecules) in water media.

CO2 capture. Industrial process optimization.

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

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CO2 capture belongs to frequent industrial needs, both in the cases of low concentration CO2 removal from waste gases and in the cases of main process streams, e.g., in hydrogen production, when high amount/concentration is to be removed. Just the last example represents the process, which the PhD thesis will be focused to. In the premises of Unipetrol company, the CO2 capture unit is presumed to be permanently optimized. In accordance with the needs of the industrial partner, the experimental research goals will involve i) durability / degradability of the solution currently used in the process, ii)absorption efficiencies and selectivities (H2S/CO2) of new absorbents and iii)the influence of low concentration admixtures, e.g., Fe, Ni and V metals, on the CO2 capture efficiency. The PhD student will acquire valuable experience of industrial area life because he/she will be able independently act in the Unipetrol premises, will cooperate with industrial research department UniCRE and will find here both well-equipped laboratories and experienced consultants.

Characterization and modelling of dispersion systems with variable viscosity

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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The goal of this project is to characterize and model systems where viscosity of the dispersed phase is rising during the process. Typical examples are emulsification, suspension polymerization or spherical agglomeration. The student will start with simplified system composed of two liquid phases with various viscosities, which will be analyzed by on-line sensors providing information about the droplets sizes. Experimental activity will cover both batch as well as continuous operation modes. Collected data will be consequently used to develop engineering model based on computational fluid dynamic of the fluid flow coupled with population balances to describe coalescence and breakup of dispersed phase for various levels of dispersed phase viscosity. An extension of this activity will be process of spherical agglomeration where dispersed phase will contain particles (nanoparticles or crystals), which can undergo agglomeration and thus increasing the viscosity of the dispersed phase. Developed model will be validated against experimental data collected at various scales or operating conditions.

Characterization and modelling of dispersion systems with variable viscosity

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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The goal of this project is to characterize and model systems where viscosity of the dispersed phase is rising during the process. Typical examples are emulsification, suspension polymerization or spherical agglomeration. The student will start with simplified system composed of two liquid phases with various viscosities, which will be analyzed by on-line sensors providing information about the droplets sizes. Experimental activity will cover both batch as well as continuous operation modes. Collected data will be consequently used to develop engineering model based on computational fluid dynamic of the fluid flow coupled with population balances to describe coalescence and breakup of dispersed phase for various levels of dispersed phase viscosity. An extension of this activity will be process of spherical agglomeration where dispersed phase will contain particles (nanoparticles or crystals), which can undergo agglomeration and thus increasing the viscosity of the dispersed phase. Developed model will be validated against experimental data collected at various scales or operating conditions.

Continuous preparation of multicomponent drug solid forms

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Screening of new solid forms is typically done in small scale systems including shaken flasks, evaporating systems, ball mills etc., which by design operate in a batch model. Once new solid form is discovered scaling its production is often very complex task. In this project we plan to test capability to utilize the rotary extruder to prepare multicomponent solid forms of drug substances such as salts, co-crystals or co-amorphs. Initially we will use ball mill to prepare new solid forms of selected drug substance. Upon characterization we will upscale of the production process to the application of extrusion, where same form of the drug substance will be prepared in a continuous mode. Detailed investigation of the process parameters will be done to optimize the production process. Both products will be thoroughly characterized including XRD, NMR, Raman spectroscopy, DSC, SEM, particle characterization, measurement of dissolution and stability testing.

Controlling drug crystals properties during crystallization and their impact on consequent unit operations

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Active Pharmaceutical Ingredients (APIs) are commonly small molecules, which are prepared by chemical synthesis followed by crystallization process. Properties of prepared crystals (i.e. physico-chemical but also formulation properties) are strongly dependent on the used drug solid form, their size and crystal morphology. Therefore, the focus of this project is to study impact of crystallization process parameters and post-processing step on the prepared drug crystals with respect to size, morphology and polymorphism. Temperature modulated batch crystallization will be combined with wet-milling process to control the shape as well as flow properties of prepared drug crystals. Crystallization step will be combined with filtration and drying, to evaluate the impact of the crystal size and shape on the efficiency of these unit operations. In parallel, we will also study impact of washing step on the amount of remaining solvent and the polymorphic stability of the final product. While pharmaceutical industry is typically using batch operation, as a part of this project we will investigate the possibility to prepare same drug crystals as studied in batch mode in a continuous process. Process analytical technology capable to measure crystal size, shape and morphology combined will analysis of composition via Raman spectroscopy will be used to ensure constant product quality. On-line measurement will be supported by off-line measurement via SEM, IR spectroscopy, XRD and NMR. Student will be also involved in the scale up of developed process.

Design and application of supra-lipidic structures

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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The gastro-intestinal transit, emulsification, digestion and absorption of lipidic components from food is crucial not only from the nutritional point of view but also for the dissolution and absorption of many drugs, and therefore their bioavailability. An increasing number of active pharmaceutical ingredients (APIs) that enter the drug development process are highly lipophilic, which makes their bioavailability susceptible to patient-specific dietary habits and often leads to undesired phenomena such as positive food effect. For some APIs, the bioavailability can be up to five times higher when taken on a full stomach compared to bioavailability in the fasted state. The aim of this project is to develop a formulation platform that would make the dissolution, absorption and pharmacokinetics of lipophilic APIs independent of food intake, while not containing a large amount of lipids in the formulation itself. The idea is to create particles that “look like lipids” on the outside but their volume contains predominantly the API or other excipients. Such structures can include e.g. drug suspensions encapsulated in giant liposomes or their aggregates, drug nanocrystals coated by a phospholipid monolayer, or drug-loaded mesoporous silica particles encapsulated within a lipid bi-layer. These elementary structures can also be combined, carrying e.g. several different APIs, functional excipients for absorption enhancement, or pH modifiers that can further reduce patient-to-patient variability.

Design and optimization of 3D printed catalytic supports for gas-liquid flow conditions

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

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3D printing technology provides new possibilities for the design and fabrication of chemical reactors and catalyst supports. Principally it brings the possibility to tailor the device or catalyst support to the selected process. Therefore, this work’s objective is the design and 3D printing of an optimal structure of catalyst support that is tailored to a model heterogeneous reaction. The optimized design will result from an experimental study of single- and two-phase flow hydrodynamics through structured fillings and process modeling by CFD (OpenFOAM, ANSYS Fluent). The candidate should have a good knowledge of chemical and reaction engineering and have good computer skills to learn data acquisition and evaluation systems, mathematical modeling software and 3D printing process. To complete the delegated tasks, personal abilities such as independence, creativity, and teamwork will be required.

Development and application of a digital twin bioreactor model for modelling of production of biopharmaceuticals

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Production of biopharmaceuticals is typically done in a stirred and sparged bioreactors, which combine a fluid flow and microorganism metabolism to produce final product with desired amount and quality. However, often interplay between poor mixing, low dissolved oxygen concentrations, high amount of CO2 and hydrodynamic stress negatively affect the cell behavior resulting in a lower product amount and decreased product quality. In this project we will use recently development CFD model of stirred and sparged bioreactor capable to predict hydrodynamic stress and mixing time and extend it to descritpion of dissolved O2 and CO2 concentrations, uptake of nutrients and release of metabolic products. Information about the fluid flow will be combined with a hybrid model describing detailed microbial metabolism. Tuning of model parameters and its testing will be done against experimental data measured in fermenters of various sizes. Once validated, developed model will be used to test and propose modifications of existing fermenters to optimize the fermentation process.

Development of 3D cell cultures for the evaluation of drug delivery systems

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

Development of nanoparticles for drug delivery in wound healing

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Main focus of this project is to synthesize multifunctional vesicles loaded with hydrophilic and hydrophobic drugs to be used in wound healing. Since these particles can be used directly or as an intermediate during skin dressing their detailed characterization and colloidal stability will be essential. Student will study the impact of vesicle composition (primary system will be surfactant and cholesterol forming niosomes) and method of preparation on the size and properties of the formed nano carriers as well as drug encapsulation efficiency. Once drug will be loaded into vesicles the release kinetics will be measured as a function of molecular weight of used surfactants and ionic strength. Quality of the prepared samples will be characterized by combination of analytical techniques including 3D modulated DLS, Depolarized DLS, static light scattering, optical video microscopy combined with image analysis and cryo-TEM. While batch production mode is simple to realize, part of the project will be also preparation of multifunctional vesicles in microfluidic systems and compare their properties with batch production method.

Development of nanoparticles for drug delivery in wound healing

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Main focus of this project is to synthesize multifunctional vesicles loaded with hydrophilic and hydrophobic drugs to be used in wound healing. Since these particles can be used directly or as an intermediate during skin dressing their detailed characterization and colloidal stability will be essential. Student will study the impact of vesicle composition (primary system will be surfactant and cholesterol forming niosomes) and method of preparation on the size and properties of the formed nano carriers as well as drug encapsulation efficiency. Once drug will be loaded into vesicles the release kinetics will be measured as a function of molecular weight of used surfactants and ionic strength. Quality of the prepared samples will be characterized by combination of analytical techniques including 3D modulated DLS, Depolarized DLS, static light scattering, optical video microscopy combined with image analysis and cryo-TEM. While batch production mode is simple to realize, part of the project will be also preparation of multifunctional vesicles in microfluidic systems and compare their properties with batch production method.

Development of scaling-up methods of industrial mechanically agitated reactors

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

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Fermenters or, in general, mechanically agitated aerated vessels are frequently used in industry for the intensification of gas-liquid mass transfer, especially in the case of a low gas to liquid volume ratio. Industrial processes as aerobic fermentations, hydrogenations and chlorinations can serve as examples of their application. In many processes the gas-liquid interfacial mass transfer becomes the rate determining step, so the volumetric mass transfer coefficient becomes the key parameter in the design. Mass transfer laboratory pays many year effort to gas-liquid mass transfer measurement in mechanically agitated gas-liquid dispersions with the aim to formulate the scaling-up rules for industrial vessels design. In the frame of this research an extensive experimental work has been done using various batch types (coalescent, non-coalescent, viscous) and for various impeller types (from purely axially pumping to purely radially pumping ones) and their combinations. After collecting large data series in laboratory scale vessels, experimental work continues using pilot-plant vessel equipped with a modern computer controlled regulation and data acquisition system in the form used also in industry. The aim of the PhD work is to collect the transport characteristics (impeller power, gas hold-up and volumetric mass transfer coefficient, kLa) measured in the pilot-plant vessel using various types of impellers (e.g., Rushton Turbine, Lightnin, Techmix, Pitched Blade impellers). The experimental research will be now focused to the transport characteristics in viscous batch and in the presence of solid particles. Both high viscosity and solid particles presence are typical features of industrial fermentation broths. Based both on the laboratory data and on the pilot-plant data the scaling-up rules will be formulated, which will be employable for industrial gas-liquid contactors design. A PhD student will get acquainted with the design methods of other gas-liquid and vapour-liquid processes as well, because he/she will work in the team dealing also with the absorption columns, distillation columns and ejector bubble columns design. More info: Tomáš Moucha, UCT building B, ground floor, room No. T02a, phone: 220 443 299, e-mail: mouchat@vscht.cz

Dynamics of multi-phase systems: gas-liquid-solid

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Multiphase systems are all around us, in nature and in industry technologies and applications (sedimentation, fluidization, bubble columns, flotation apparatuses, etc.). Due to the complexity and applicability of these systems, it is seriously worth to study their hydrodynamic aspects. The present PhD research will focus on the experimental and theoretical description of processes controlling multiphase dispersions at microscale level (like bubble coalescence, bubble-particle collision) and their consequences on the flow regimes at the macroscale level (bubble columns, flotation apparatus, etc.). The obtained results will be valuable in many industrial applications (chemical and oil industry, food processing, metallurgy, pharmaceutical and environmental industry). Requirements
• Master degree in chemical or mechanical engineering, or physics and mathematics
• ability and willingness to study
• creative approach and team-work

Effect of liquid physical properties on the mass transfer in various types of bioreactors

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: Ing. Mária Zedníková, Ph.D.

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The production of new products in the field of biotechnology and pharmacy is often associated with a continuous change in the physical properties of liquids during the fermentation process. The physical properties of the batch mainly affect the mass transfer between gas and liquid and therefore they play a key role in the design of the bioreactor. The aim of the doctoral thesis is to study the mass transfer depending on the physical properties of used liquid media (viscosity, presence of various salts and surfactants) in the three types of the most commonly used bioreactors.
The work is intended as the cooperation of ICPF of the CAS (supervisor's workplace) and UCT Prague (consultant's workplace) appropriately complementing the second PhD topic offered by the consultant. Both cooperating workplaces are well equipped by necessary facilities i) stirred tank reactor, ii) bubble column and iii) air-lift reactor. All bioreactors are adapted to measure the volumetric mass transfer coefficient by the same methods, therefore the results will be comparable.
Requirements for an applicant: master degree in chemical or mechanical engineering, organic technology, biotechnology etc.; ability for teamwork; systematic and creative approach to scientific problems; interest in experimental work.

Erosion-controlled drug release from super-placebo tablets

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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The rate of drug release from a pharmaceutical tablet is one of its most important quality attributes. As an ever-increasing number of Active Pharmaceutical Ingredients (APIs) are developed in alternative solid-state forms such as metastable polymorphs, co-crystals or amorphs, it is desirable to control the rate of drug release by the properties of the tablet matrix rather than by the properties of the API itself. The aim of this project is to explore the so-called “super-placebo” concept, i.e. tablets that erode in a defined way which is independent of the API they contain. The project will systematically explore the relationship between the rate of tablet erosion, the proportion of soluble and insoluble excipients (e.g. mannitol, microcrystalline cellulose), and the manufacturing process parameters (e.g. compaction pressure). The ability to control drug release rate will be demonstrated using several real-world APIs. Advanced instrumental methods such as Magnetic Resonance Imaging, x-ray micro CT and high-speed video-imaging will be used in order to gain a deep understanding of the underlying tablet erosion mechanisms.

Formation of Microstructured Materials through Self-Assembly

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: RNDr. Ivan Řehoř, Ph.D.

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Self-assembly is a spontaneous arrangement of individual units - building blocks - into an ordered structure. The ordered structure has the lowest energy from all accessible building block arrangements, which drives the assembly process. The arrangement of the ordered structure is defined by the properties of the building blocks, such as their shape, material anisotropy or magnetic interaction with external field. Tailoring these properties to achieve desired structure can be considered 'programming' and may represent viable alternative to other ways of constructing micro and nanostructured materials. The question of lengthscales is crucial in self-assembly. When building blocks are small enough (We recently demonstrated, that we can assemble anisotropic hydrogel microparticles on solid liquid interface to form ordered 2D structures. We introduced novel mechanisms to control orientation of the building blocks during the self-assembly process and, thus, to not freeze in the disorderedd state. Ordered microparticles can be subsequently covalently bound together. The resulting structure - sheet - has complex mechanical properties i.e. ability to buckle in a preprogrammed way determined by the shape, size and material composition of the building blocks. The goal of the project is to find new approaches to the self-assembly of hydrogel microparticles and combine them with directed asembly methods using mobile microrobots developed in our team (https://www.youtube.com/watch?v=PQOXS7f9rDg). Resulting structures will find application in the preparation of metamaterials, microrobotics or tissue engineering.

Formation of microparticles from natural extracts using supercritical CO2

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: Ing. Marie Sajfrtová, Ph.D.

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Natural extracts are marketed in the form of liquid, viscous preparations or as powders resulting from the drying of the liquid extract. Formation of powdered extracts helps to decrease the storage costs and increase the concentration and stability of active substances. However, conventional drying methods (spray drying, lyophilization etc.) have several disadvantages, such as the degradation of the product, contamination with organic solvents, and the production of large sized particles. More gentle technic for precipitation and particle formation is a supercritical antisolvent process (SAS). In the SAS process, a liquid solution of a solvent and a bioactive substance is injected into a supercritical fluid, which acts as antisolvent. This leads to supersaturation of the solute, which is compensated by nucleation and particle growth. The aim of the thesis is to evaluate the effects of pressure, temperature, solute concentration etc., on the properties of the particles produced by SAS from particular plant extract. Requirements:
• University degree in food chemistry and technology, natural substances, chemical engineering or organic technology.
• Positive and systematic approach to work duties, motivated, reliable.

Formulation and bioavailability of natural poly-actives

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Current paradigm in pharmaceutical drug development and its regulatory environment is based on the concept of Active Pharmaceutical Ingredient (API) as a well-defined single molecular entity that is contained in the dosage form at a precise quantity and chemical purity. Although rational in many ways, this approach is rather different from evolution-proof substances found in Nature. The main drawback is single-API medicines is the development of drug resistance over historically extremely short time periods (only a few decades), which is problematic not only in the area of antibiotics but also in cancer treatment, anti-fungal and various anti-parasitic drugs that gradually lose their effectiveness. In contrast, there are examples of natural systems that maintain their efficacy for many millennia. Perhaps the most prominent example of such material is bee propolis. Chemically, propolis is a mixture of several hundred chemical species with location- and season-dependent composition, which would completely disqualify it as a registered medicinal substance. However, it is exactly this variable multi-component character that makes is so robust and durable, not giving pathogens a chance to develop resistance. Propolis contains both water-soluble and water-insoluble components and is typically applied as ethanol dispersion only for surface treatment. The aim of this project is to explore formulation approaches that could enable oral administration of propolis and ensure its safety and bioavailability. The project is multidisciplinary and will include not only formulation and analytical work, but also in vitro and in vivo testing of biological efficacy.

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.

Green, greener, greenest: thermodynamic properties of aqueous solutions of bio-based ionic liquids

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: Ing. Magdalena Bendová, Ph.D.

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The aim of this project is to gain a better understanding of the structure-property relationships in aqueous mixtures of choline-based ionic liquids (ILs) with various anions. Thermophysical and thermodynamic characterization of new ILs and their aqueous mixtures will be performed. Ionic liquids in general show a pronounced application potential e.g. in energy storage or separation processes. Furthermore, the relation between their structure and properties remains to a large extent unclarified, due to a very large number of structures that could be synthesized. Understanding these relationships in bio-based ionic liquids are particularly interesting in this regard. Water as one of the most ubiquitous and possibly greenest solvent is then a substance of choice when it comes to understanding the properties of mixtures. Required education and skills
• Master degree in physical chemistry, organic technology, chemical physics, chemical engineering;
• willingness to do experimental work and learn new things;
• team work ability.

High-throughput development and continuous manufacturing of SMEDD systems

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Self micro-emulsifying drug delivery systems (SMEDDS) are formulations that spontaneously form a mini- or micro-emulsion upon contact with water. They typically contain the active pharmaceutical ingredient (API), a mixture of oils or low-melting lipids in which the API is soluble, and one or more surfactants and co-surfactants. SMEDDS are complex ternary or higher-order mixtures whose phase behaviour and properties are notoriously difficult to predict at present. Therefore, the development of SMEDDS is to a large extent an empirical process. Due to a large number of formulation components and their possible ratios, it is rarely possible to completely cover the entire design space, which may lead to sub-optimum formulations or even a false rejection of a particular API as non-formulatable. The aim of this project is to construct a device and develop a methodology for automatic combinatorial screening of SMEDDS formulations and their continuous manufacturing based on the so-called liquid marbles. The project will build on a recently developed patented device called “Marblemat” and extend its capabilities towards combinatorial mixing of formulation components and serial production of liquid marbles with systematically varying composition. Simultaneously, capability for high-throughput testing of the formulation properties such as mechanical strength, temperature stability and dissolution properties will be implemented and demonstrated on several industry-relevant APIs.

Hydrogels and their nanocomposites

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: Ing. Jaroslav Tihon, CSc.

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Hydrogels are cross-linked polymers containing a large amount of water. They can be used, for instance, in medicine (contact lens, wound dressing materials, tissue engineering), and in vaste water treatment (they exhibit high adsorption ability for organic dyes). When suitable nanoparticles (mostly anorganic) are incorporated into a hydrogel structure, hydrogel nanocomposites are formed. They often exhibit even better physicaly-chemical properties than original hydrogels – typically their rigidity increases, and water swelling, pollutants adsorption or drug releasing ability changes. In this project, the preparation of novel hydrogel nanocomposites, their physicaly-chemical properties and potential using in the field of medicine and environmental engineering will be studied. The candidate should have a M.Sc. degree in chemical engineering, physical chemistry, or in a similar applied science field. Some experimental skill is appreciated. However, the enthusiasm for scientific work is only the principal requirement.

Influence of composite particle structure for targeted drug delivery

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: Ing. Viola Tokárová, Ph.D.

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The encapsulation of active substances in microscopic carriers finds its practical application in the food industry, cosmetics and pharmacy. The active substance is thus protected from the environment and can be delivered to the target site of action (eg: damaged tissue, tumour cells). The aim of this work is to prepare particles with diverse architecture and topography (eg: core-shell, particles with microtopography, fibrous structure) and to investigate the influence of particle architecture on release kinetics of encapsulated active ingredient. Methods of spray drying, encapsulation and microfluidics will be used for the preparation of composite particle systems in this work. The active ingredient will be selected with respect to the biomedical application.

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.

KLa - shear stress coupling to design fermenters better

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

Annotation

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.

Liquid-gas ejector as compact and economic reactor

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: Ing. Jan Haidl, Ph.D.

Mathematical modeling of microfluidic devices for separation of racemic

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Microfluidic devices are characterized by a large ratio of interfacial area to internal volume. This can be used in chemical separations by extraction or membrane processes. Separation of optically active substances, often important pharmaceutical or food products, at membranes or sorbents with anchored chiral selectors represents a great challenge for chemical engineers. Mathematical modeling can lead to a better understanding of complex processes in such devices and consequently to the design of efficient microfluidic separators. The main objectives of the PhD project are: Based on preliminary and available experimental data, a mathematical-physical description of mass and momentum transport in microfluidic devices with anchored chiral selectors will be developed. Mathematical models of processes on different spatial scales will be created. They will include description of transport of the separated chemicals by diffusion, convection and electromigration. Models will be analyzed numerically. Parameter values that ensure high separation efficiency and high productivity of the microfluidic system will be searched in the parameter space. The lab is equipped with modern computers. The participation of the doctoral student in grant projects and active participation in international scientific conferences is expected.

Membrane separation of fermentation primary products

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

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In biotechnologies, batch processes are often used, in which living cultures/biomass are used. Metabolites produced by culture are often poisonous and can damage the culture itself, as an example of which can serve ethanol fermentation. In periodic processes, the initial periods including sterilizing, nutrient dosing, etc., used to be time consuming, financially burdening. Therefore, it is desirable to dedicate an effort to develope continuous performance of such processes. One of the operations ensuring the process continualization can be membrane separation. This case brings the necessity of two membranes modules: i) microfiltration to separate solid particles-biomass and ii) pervaporation to separate primary product of fermentation, e.g., ethanol, as mentioned above. The goal of this work is to experimentally develop two step membarne separation technique, including microfiltration and pervaporation, to be prepared for an interconnection with a fermenter. THe development will be conducted from the viewpoint of chemical engineering. The reached separation parameters (selectivity, permeability) will be investigated in dependency on the process parameters (pressure, flowrate, temperature, feed composition). Chemical engineering quantities (membrain polarization module, mass transfer coefficient,...) will be used to describe these dependencies. At the workplace the new membrane modules are available, which were purchased for the purpose of this development. The PhD student will get familier both with industrial membrane module and with the custom made one. In addition to being familiar with modern technologies introduced in industry, the PhD student will also work in the team of students and academic staff who are experienced in industrial cooperation. PhD study will prepare the student to obtain either qualified working position in industry or to be able systematically conduct further research from the viewpoint of qualified chemical engineer. Further information Assoc. Prof. Tomáš Moucha, UCT Prague, building B, room T02, email: tomas.mooucha@vscht.cz

Micro-scale mathematical modeling of gas-liquid transport in catalyst pores

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

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The work focuses on the development of advanced mathematical models for simulations of mass transport in multiphase systems gas-liquid indide pores of a solid catalyst, including phase change (evaporation, condensation). The models are developed in the CFD environment OpenFOAM and utilize 3D-reconstructed structures of porous materials obtained from X-ray tomography (XRT) and electron microscopy. The model results are further verified with the available experimental data from lab reactor.

Microfluidic systems for the synthesis and separation of optically active

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Microfluidic reactors and separators are modern devices that represent an alternative to conventional batch and flow systems used in biotechnology. The small spatial scale ensures reproducible reaction conditions and intensive mass and heat transfer. Microfluidic devices generally lack moving parts and allow easy combination of many unit operations such as mixers, separators, reactors. The main objectives of the PhD project are: Study of kinetics of selected enzymatic reactions, which lead to production of optically active chemicals that are used in pharmacy, food industry or synthesis of chemical specialties. Design and fabrication of microfluidic separators with embedded membrane or sorbents with attached chiral selectors for separation of racemic mixtures. Testing of manufactured microfluidic devices for selective separation of selected optically active compounds. Evaluation of the possibility of accelerated transport of optically active substances through membranes by means of an imposed electric field. The lab is equipped with technologies for the production of microfluidic systems, modern measuring instruments and powerful computers. The participation of the doctoral student in grant projects and active participation in international scientific conferences is expected.

Mixing and segregation of granular materials

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Unlike liquids, the issue of segregation must also be addressed when mixing granular systems. Granular systems contain a large number of particles. However, the individual grains are not identical but may differ in size, density, hardness, shape, or other physical-chemical properties. This type of difference during particle motions often ultimately leads to the segregation of material with different properties. Although the segregation is a ubiquitous phenomenon that causes different dynamic behavior of granular particles, the reasons for its formation, intensity, and prediction of the resulting system behavior are not always completely clear. This work investigates the mechanisms of segregation during the mixing process and its effect on the dynamics of granular materials. The research will be carried out mainly using numerical simulations using the discrete element method. Required education and skills
• Master degree in chemical engineering, mathematical modeling, computer science;
• high motivation, willingness to learn new things;
• team spirit.

Modeling of particles adhesion and breakage during processing of powder materials

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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During the processing of powder materials, intense force interactions occur between the particles, resulting in the particles' adhesion to larger agglomerates or, conversely, their destruction and subsequent breaking. The adhesion of particles due to attractive interparticle interactions connected with particle's deformation is controlled by combining the grains' surface properties and the forces acting on the interacting particles. Particle breakage results from the interaction between the particle's internal strength and the forces acting on the particle. This work aims to describe the influence of adhesion and particle breakage on the powder materials' dynamics and transport properties. The research will be carried out mainly using numerical simulations using the discrete element method. It is assumed that adhesion's origin will be described by the theory of Johnson, Kendall, and Roberts. Models describing elastic bonds based on the definition of stiffness and bond damping will be used for particle breaking. Required education and skills
• Master degree in chemical engineering, physics, mathematical modeling, computer science;
• high motivation, willingness to learn new things, team spirit.

Modular Hydrogel Microrobots

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: RNDr. Ivan Řehoř, Ph.D.

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Miniturization of robots to the sizes of tens of microns will allow their application in new, currently inacccesible areas, such as controlled drug delivery or microsurgery. In order to simplify the mechatronic design of such microrobots, novel approaches have been adopted for their operation and control, exploiting soft materials, actuating through deformation, such as responsive polymers. These advanced materials, together with development of their processing in microscales gave rise to soft microrobots capable of independent untethered motion or manipulation with other objects . In our group, we have recently developed hydrogel microrobots, crawling over surfaces, powered by light (https://www.youtube.com/watch?v=PQOXS7f9rDg). Many of the visionary real-life applications of microrobots foresee their ability to autonomously cooperate and connect into greater structures, that will perform tasks, inaccessible to the individual robots. Modular connectivity of macroscopic locomotive robots has been tackled experimentaly, demonstrating the extended application of such robot assemblies, compared to the individual robots. The connective mechanisms and the organization of the individual robots into the assembly however remains a complex and challenging task. This project aims to probe potential pathways for the connection of crawling hydrogel microrobots into actuating millimeter-sized structures, capable of performing mechanical work.

Nanostructured biomimetic surfaces with antibacterial effect

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: Ing. Viola Tokárová, Ph.D.

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Biomimetic materials developed thanks to new technologies have a unique function inspired by the biomaterials and their structure occurring in nature. One of the areas of biomimetics is topographic surfaces with antibacterial property. The subject of the work is the mapping of the topography of natural materials, such as the wings of selected representatives of dragonflies or rose petals and replication of the structures into suitable material that can be applied in biomedicine (e.g., implants). The aim is to focus on nanostructured topography and to characterize both surfaces, natural and replicated, and to test the antibacterial property of replicas against different bacterial strains (e.g. infections associated with postoperative medical care).

Naturally sourced particles for drug encapsulation and delivery

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Drug encapsulation into a suitable carrier particle is a common method used in situations where it is possible to either modify the surface properties (e.g. powder flowability or dispersibility in water), to protect the encapsulated component from the environment (e.g. enzymatic digestion in the GI tract) or to control the rate of drug release. Several man-made encapsulation processes are known. However, there are also many natural systems that rely on encapsulation – the cell walls of single cell organisms or their spores, natural particles such as pollen, extra-cellular vesicles, or sub-cellular structures such as vacuoles or other organelles. Some of these structures are highly specific in terms of drug diffusion and its selectivity, or in terms of recognition by cells of the immune system e.g. due to specific shape of the presence of immunomodulatory functional groups on the surface. Yeast glucan particles can serve as a prime example. The aim of this inter-disciplinary project is to investigate the potential of several different types of naturally sourced particles in drug formulation and drug delivery. Both cell-wall derived particles and organelle-based particles will be considered. Special attention will be paid to the process of particle extraction and isolation, as well to the drug encapsulation methodology.

Oleogels for drug delivery

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Oleogels, like hydrogels, are semi-solid materials that can contain up to 99 % of a liquid, which is solidified by a three-dimensional polymer network. While hydrogels contain as the liquid and the polymers are hydrophilic, oleogels contain oil and an oleophilic polymer network. Many APIs that are poorly soluble in water could potentially be formulated using oleogels and be either directly dissolved in the oil phase or form a particle depot that would dissolve in the oil gradually and act as a longer-lasting reservoir. The aim of this project is to evaluate the suitablitity of selected oleogel formulations for drug delivery applications from the point of view of manufacturability, drug release kinetics, drug stability, and biological compatibility. The application of oleogels will be demonstrated using several selected APIs both in vitro and in vivo.

On-line measurement and control of continuous pharmaceutical manufacturing

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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The manufacturing of pharmaceutical products is typically carried out batch-wise. While this makes sense for products that are manufactured only occasionally in small quantities, batch processes also have several drawbacks. These include excessive dead-times, need for cleaning to avoid cross-contamination, and generally poorer control over the product quality. By switching pharmaceutical manufacturing to a continuous mode, equipment utilisation can be increased theoretically to 100 %, the footprint of the facilities can be substantially reduced, and standard feed-back and feed-forward control schemes applied. A crucial component of continuous manufacturing processes is on-line measurement of key quality attributes such as particle size distribution, composition uniformity of granular blends, or moisture content. Advanced analytical instruments such as Near-Infrared probes can be used for this purpose. The aim of this project is to explore the on-line measurement and control methods for continuous pharmaceutical manufacturing in an industrial setting and combine them with computer simulation tools in order to optimize the overall process robustness and operability.

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

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: prof. 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.

Porous catalytic layers in structured reactors

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

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The work focuses on preparation and coating of porous catalytic layers in structured reactors such as honeycomb monoliths, filters, porous membranes and open foams. The aim is to intensify the reactor operation with respect to utilization of the catalytic material and mass and heat tranfer. Industrially relevant processes such as exhaust gas conversion, partial oxidation and reforming of methane will be studied. Morphology of the samples will be analyzed by electron microscopy (SEM, TEM) and X-ray tomography (XRT). Impact of the microstructure on the overall performance of the device will be tested in a lab reactor. The topic is supported by the leading catalyst manufacturer Johnson Matthey.

Preparation of drug delivery carriers for treatment of rheumatoid arthritis

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Rheumatoid arthritis (RA) is a chronic autoimmune disorder, mainly affecting joints that are identified by inflammation and swelling of the synovium of the joint. Today, apart from the conventional synthetic disease-modifying antirheumatic drugs (DMARDs), a number of biological DMARDs have been approved. Recently the first targeted synthetic DMARD has also been approved, while other targeted compounds are in the development phase. Particularly interesting is group of drugs which are based on gold complexes. Despite their promising properties, these drugs has low solubility in water and thus low bioavailability. Therefore, within this project we plan to investigate possibility to prepare more soluble compounds of gold complexes using crystal engineering approach as well as formulate these drugs into various nanocarriers. Combination of various preparation and analytical techniques will be used to investigate stability of gold complexes. In the next step we will investigate the impact of encapsulation matrix or complexation partner on the dissolution characteristics of gold complexes.

Preparation of porous materials for enzyme immobilization and their application in biocatalysis

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Application of enzymes for preparation of various biomolecules is ever growing field. This is due to low energy demand and high specificity of the catalyzed reactions. Significant disadvantage of this technology is loss of enzyme activity and removal of the enzyme from the reaction system. Possible solution for these problems is enzyme immobilization onto a suitable support. In this project we will use recently developed technology of reactive gelation suitable for synthesis of 3D porous material with tunable porosity and pore size distribution combined with covalent attachment of enzymes to the surface of prepare material. To understand impact of enzyme-surface interactions we plan to use various building blocks made out of polymers or silica combined with different spacer molecules placed between porous material and enzyme. In this way we will be able to study impact of these interactions on the enzyme activity and yield of biocatalytic reaction. Once the system will be established, we will further investigate effect of process conditions (dispersed porous aggregates vs. packed bed), effect of ionic strength, pH, substrate concentration etc., on the yield and selectivity of the performed enzymatic reaction. In the last part of the project, the system will be extended towards multiple consequent enzymatically catalyzed reactions. Student will be involved in the preparation of porous material and its characterization as well as in the surface functionalization with suitable enzyme anchoring moieties. Consequently, student will be responsible for enzyme attachment and testing of its activity and yield. Combination of several analytical techniques including SEM, light scattering, BET measurement, Hg porosimetry, XPS, HPLC etc., will be used to characterize material properties and test behavior of immobilized enzymes.

Process scale-up of pharmaceutical spray drying

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Spray drying is versatile method for converting solutions, suspensions or pastes into dry, free-flowing powders in the pharmaceutical, food and nutraceutical industries. During product development, the formulation and process variables are typically optimised using a laboratory-scale spray dryer, and the process is then transferred to a pilot or full manufacturing scale. However, it is notoriously difficult to maintain the same particle properties using spray dryers at different scales, which often necessitated long and expensive trials to be carried out at the large scale. The aim of this project is to develop a robust methodology for spray drying process scale-up in an industrial pharmaceutical setting. The main focus will on the transferability of particle size and particle morphology, as these two parameters are known to be the most sensitive to parameters that vary between the laboratory and the manufacturing scale spray-dryers: the initial droplet size and the drying conditions (temperature, gas flowrate, and residence time in the drying chamber).

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

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: prof. 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).

Strength and fluidity of granular media

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Mechanics of granular media (sand, clay, silt, debris, etc.) is central to many problems in geology and technology. Natural hazards such as earthquakes or landslides are triggered by mechanical instability of embedded granular gauges. On the other hand, conditions leading to good fluidity of granular media are often sought in civil engineering, pharmacy, and chemical technology. Therefore, understanding of mechanisms controlling the strength of granular media is of high importance. The student will run computer simulations of a shearing granular layer and will study conditions leading to flow. The resulting theoretical picture should enlighten mechanisms that are most effective in degrading mechanical strength. In particular, the effect of pore fluid and oscillations of boundaries will be studied in detail. Required education and skills
• Master degree in chemical engineering, physics, geology, mathematical modeling, computer science;
• high motivation, willingness to learn new things;
• team spirit.

Study and preparation of nanoparticles in controlled conditions of microfluidic arrangement

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: Ing. Viola Tokárová, Ph.D.

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Properties of nanoparticles (e.g., optical, electromagnetic or mechanical) depend on particle size, morphology and structure and there is an increasing demand for particles having low polydispersity and thus near-identical properties. Batch-wise particle preparation is one of the most employed techniques due to its straightforward character and feasibility of instrumentation. However, the use of batch-wise synthesis is not ideal for rapid precipitation reaction given by non-ideal mixing of reactants. Mixing efficiency plays a significant role since the nucleation process triggered upon reactant mixing occurs within few milliseconds. Continuous microfluidic reactors are promising technology allowing thanks to their small dimensions, high surface to volume ratio and mixing intensification lowering of the final particle polydispersity and produce particles with superior properties compared to those produced by means of batch-wise preparation. The aim of this work will be to optimize the architecture of microfluidic channels and its effect on the mixing of the reactants with respect to the synthesis of nanoparticles of the required size.

Study of bubble and drop interactions with a vortex structure

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: Ing. Mária Zedníková, Ph.D.

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Gas-liquid or liquid-liquid dispersions are encountered in numerous technological and biotechnological processes. The fluid particles (bubbles or droplets) break in the turbulent liquid flow and form a complex multiphase system. Understanding the particle breakup mechanism at turbulent flow conditions is important because theoretical models describing this mechanism are essential for the numerical modeling of complex multiphase systems. The postgraduate project will be focused on the experimental study of dynamic behavior of bubbles and drops after their interaction with a turbulent vortex in order to determine the breakup rate of original particles and the size distribution of newly formed particles. The breakage mechanism will be studied in dependence on various hydrodynamic and physico-chemical conditions of the studied system. Department is well equipped for the study of bubble/drop breakup in turbulent flow. Cells for controlled generation of bubble, toroidal vortices and intense turbulent flow are available, as well as all the control and evaluation software. Requirements for the applicant: master degree in chemical or mechanical engineering; ability to teamwork; systematic and creative approach to scientific problems; interest in experimental work.

Study of transport characteristics in various types of bioreactors

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

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The production of new biotechnology and pharmaceutical products is based on a bioreactor design. The choice of a suitable type of bioreactor is crucial with respect to maximum yield, but it is also limited by the lifetime of the microorganisms present. The aim of the doctoral study is to compare design parameters (transport characteristics) of three types of the most commonly used bioreactors. The results will be used to characterize the differences and similarities of specific types of bioreactors in terms of gas distribution, mass transfer and mixing depending on the total energy supplied to the system. Transport characteristics will be obtained experimentally for model batches, which will be designed based on physical properties of real broths. Both cooperating departments are well equipped and have all the three types of bioreactors i) mechanically stirred reactor, ii) bubbled column and iii) air-lift reactor. All bioreactors are adapted to measure transport characteristics by the same methods, therefore the results will be comparable. Requirements for applicant: master degree in chemical or mechanical engineering, organic technology, biotechnology etc.; ability for teamwork; systematic and creative approach to scientific problems; interest in experimental work Further information: Assoc. Prof. Tomáš Moucha, building B of UCT Prague, room T02, e-mail: tomas.moucha@vscht.cz

Synthesis and characterisation of particles with immuno-adhesive properties

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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The specificity of adhesion to the target cells or tissues in a physiological envirionment is a key requisite for the successful implementation of drug delivery systems (DDS). The aim of this work is to explore DDS based on immunoliposomes and their composites (e.g. with magnetic nanoparticles) using surface modification by antibody fragments and other suitable targeting moieties. The immunoliposomes will be tested both in vitro and in vivo in terms of specificity of adhesion, pharmacokinetics, and ability do encapsulate and delivery drugs or pro-drugs.

Synthesis and characterization of nanoparticle system for transfection of cells

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Delivery of gene vectors during cell transfection is commonly done by positively charged poly ions. When coupled with DNA, this method is capable to deliver the genetic information into the host cell’s nucleus resulting in the production of the protein of interest. Even though this procedure is commonly used, toxicity of polycations results in low cell viability and loss of the culture. In this project we plan to develop a transfection system based on the biodegradable polymers with low toxicity using recently developed aggregation process. Student will be involved in the selection, synthesis and modification of the biodegradable polymer followed by the preparation of polymeric nanoparticles as a DNA carriers. Properties of the prepared polymer will be characterized via various methods include light scattering or GPC. Formed nanoparticles will be characterized by DLS, SEM/TEM, measurement of zeta potential and their colloidal stability. Consequent complexation of produced NPs with DNA and their size will be tested as well. In the last part of the project, process of complexation will be scaled up to the necessary amount to be tested with living cells.

Synthesis and characterization of nanoparticle system for transfection of cells

Department: Department of Chemical Engineering, Faculty of Chemical Engineering

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Delivery of gene vectors during cell transfection is commonly done by positively charged poly ions. When coupled with DNA, this method is capable to deliver the genetic information into the host cell’s nucleus resulting in the production of the protein of interest. Even though this procedure is commonly used, toxicity of polycations results in low cell viability and loss of the culture. In this project we plan to develop a transfection system based on the biodegradable polymers with low toxicity using recently developed aggregation process. Student will be involved in the selection, synthesis and modification of the biodegradable polymer followed by the preparation of polymeric nanoparticles as a DNA carriers. Properties of the prepared polymer will be characterized via various methods include light scattering or GPC. Formed nanoparticles will be characterized by DLS, SEM/TEM, measurement of zeta potential and their colloidal stability. Consequent complexation of produced NPs with DNA and their size will be tested as well. In the last part of the project, process of complexation will be scaled up to the necessary amount to be tested with living cells.

Transformations of aerosol particles due to changes in gaseous environment

Department: Department of Chemical Engineering, Faculty of Chemical Engineering
Theses supervisor: Ing. Vladimír Ždímal, Dr.

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The aerosol particles are omnipresent in the atmosphere, influencing many processes on the Earth starting from the global warming to health effects. They tend to be both in physical and chemical equilibrium with their gaseous environment, but due to dynamic changes in the atmosphere or during their transport to human lungs, the particles change during their lifetime. Therefore, it is necessary to study their answers to these changes to be able to predict their fate and effects after their release to or formation in the atmosphere. The study will be carried out using a newly developed system of laminar flow reactors enabling to control ambient conditions of particle neighborhood. The doctoral student is supposed to study these phenomena using advanced methods of aerosol instrumentation including on-line chemical and physical characterization of particles by aerosol mass spectrometry. Required education and skills
• Master degree in chemical engineering, physical chemistry, organic technology, chemical physics, meteorology ... ;
• willingness to do experimental work and learn new things;
• team work ability.


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