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8:30
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Bc.
Zina
Briki
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M1
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Ing. Mária Zedníková, Ph.D.
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Effect of surfactant on bubble column hydrodynamics
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detail
Effect of surfactant on bubble column hydrodynamics
Pneumatic mixing is used in various types of reactors. Surfactants can be found in the liquid phase of many bubble systems, occurring as reaction products or as additives. To understand better the effect of surfactants on these systems, research was conducted in a model bubble column system with α- terpineol as the model surfactant. It is known that the presence of surfactants alters the properties and behaviour of single bubbles (e.g., reduction of bubble velocity and size or inhibition of bubble coalescence), which ultimately results in changes in several aspects of bubble column hydrodynamics.
In this study, the hydrodynamics of bubble column was characterized by the gas hold-up, which was measured at different input gas flow rates for four (distilled water + 3) concentrations of α-terpineol. The properties of the solutions were characterized by measurements of static and dynamic surface tension and by consequent evaluation of diffusion and adsorption coefficients. The increase of concentration of α‑terpineol results in gas hold-up increase, as well as formation of stable foam‑like gas-liquid dispersion. The obtained results are correlated with the effect of α-terpineol on the contamination of bubble surface and its effect on single bubble rise and coalescence efficiency.
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8:50
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Terezie
Císařová
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B3
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Mgr. Jaroslav Hanuš, Ph.D.
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Liposomes with ladderane content for potential pharmaceutical applications
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detail
Liposomes with ladderane content for potential pharmaceutical applications
Due to covid vaccines, there has been a huge expansion of phospholipid-based drug carriers. One type of such carriers are liposomes –vesicles usable for transporting both hydrophilic and hydrophobic drugs. Unfortunately, only few types of drugs can be effectively kept inside nowadays used liposomes. Varying the composition of the liposome membrane offers a possible solution, as it dramatically changes its properties such as permeability or phase transition temperature.
In my work I focus on a new class of phospholipids - ladderane lipids – as one of the building blocks of the lipidic nanoparticles. Those can be found in anammox bacteria in its organelle’s membrane and probably cause its high density and impermeability for pH gradient, properties potentially useful for drug retention.
For the creation of lipidic vesicles I used the substrate isolated from anammox bacteria. First, I performed a scaling experiment to find the lowest concentration of lipids still suitable for liposome formation. Next, I prepared ladderane liposomes via extrusion and characterised them with dynamic light scattering and different microscopic techniques. Finally, I created ladderane-DPPC mixed particles and performed loading and release experiments to investigate their encapsulating abilities.
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9:10
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Bc.
David
Gráf
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M2
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Ing. Petr Mazúr, Ph.D.
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Optimization study of electrodeposition in zinc-air flow battery
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detail
Optimization study of electrodeposition in zinc-air flow battery
Increasing demand for cheap, effective and environmentally friendly stationary energy storages motivates modern electrochemistry research to focus on alternatives to classical Li-ion batteries. One of the promising possibilities that could meet all the aforementioned requirements and fulfil the potential of green energy sources are the zinc-air flow batteries (ZAFBs). This study deals with one of the most severe drawbacks affecting the battery lifetime, the non-homogeneous deposition of zinc during battery charging. Deposition of zinc on the current collector occurs in three different morphologies: mossy, crystalline and dendritic, however, the most suitable morphology for ZAFB turns out to be the crystalline one due to its low porosity and good adhesion to the current collector. Firstly, the geometry of the deposition half-cell was optimised with the respect to homogeneity of the flow. With the optimised geometry, we systematically studied the effect of several parameters, such as current density, deposition substrates, pre-deposited thin layers or temperature, on deposited morphologies, which were analysed by scanning electron microscopy (SEM). Furthermore, we tested the impact of modification of the flow half-cell by static mixers to improve the mass transfer of zincate ions.
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9:30
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Bc.
Zuzana
Hlavačková
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M1
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prof. Ing. František Štěpánek, Ph.D.
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Multi-drug formulations of personalized medicine by solvent impregnation
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detail
Multi-drug formulations of personalized medicine by solvent impregnation
Drugs are often prescribed to the patients in a different dosage strength from what is available on the market. The prescriptions are also in different combinations with other drugs, which leads to possible low compliance of the patient to take the medicine. Personalized medicine is based on the idea that the drugs would be created for each patient based on their individual needs. Suitable ways of producing such medicine are the 3D print, drop-on-demand (DoD) technique and others. In this work, the tablets were prepared by layer-by-layer precise droplet loading from a concentrated solution of the active pharmaceutical ingredient (API). Placebo tablets containing mesoporous silica were used as a substrate. Pores in the mesoporous silica are big enough to capture the API and small enough to prevent the recrystallisation of the API. Therefore, the API is present in its amorphous form. The aim of this work was to study the dissolution profiles from tablets with different combinations of two or three APIs. The chosen APIs that we used in this work are commonly prescribed together to treat high blood pressure. Prepared tablets were dissolved in USP apparatus type 2 and analysed by the HPLC. The crystallinity of the APIs in the tablets was studied by XRPD.
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9:50
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Bc.
Tomáš
Hlavatý
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M2
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Ing. Martin Isoz, Ph.D.
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Developing a coupled CFD solver for mass, momentum and heat transport in catalytic filters
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detail
Developing a coupled CFD solver for mass, momentum and heat transport in catalytic filters
Historically, the automotive exhaust gas after-treatment comprised multiple groups of devices – particulate matter filters and catalytic converters. However, a recent trend is to combine these devices into a single one, a catalytic filter (CF). Such a combination allows to decrease the system heat losses and facilitates the CF regeneration. On the other hand, the CF overall performance is strongly dependent on the catalytic material distribution within it. In the present work, we aim to provide a computational tool to study the dependence of the CF characteristics, i.e. the pressure loss and the conversion of gaseous pollutants, on the catalyst distribution. Previously, an isothermal computational fluid dynamics (CFD) model of the flow and conversion of gaseous pollutants inside the CF was built. However, the reactions occurring inside the CF are exothermic and the assumption of constant temperature proved to be too restricting for real-life applications of the developed CFD model. Thus, in this work, we extend the framework by the enthalpy balance, which requires coupling all the transport equations (mass, momentum and enthalpy) in a single solver. The new and more general solver is verified against results of an existing surrogate model calibrated on experimental data.
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10:30
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Mathis
Leemann
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B3
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doc.Ing. Jitka Čejková, Ph.D.
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Chemobrionics - The Study of Chemical Gardens
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detail
Chemobrionics - The Study of Chemical Gardens
Chemical gardens are well-known self-organizing macroscopic systems created by precipitation reaction. Nevertheless, yet not all aspects of their growth are understood and the field termed “chemobrionics” aims to study them. This work focuses on how the various parameters influence the structure and morphology of the chemical gardens in sodium silicate solution, namely the composition of the system (various salts and various water glass concentrations are compared, a novel solid crystalline mixture is introduced). There are two main ways how to create chemical gardens which are (i) the injection of aqueous salt solution and (ii) the general solid seeding method and these two methods and their advantages and drawbacks are compared. Then, the emergent structures are investigated, specifically the number of chimneys and their size, further the morphology and structure is studied by using scanning electron microscope. In addition, a 1.5 m long copper chloride chemical garden was created to study the stability of the chimneys growth. For the undeniable aesthetics side of chemical gardens, an artistic video with inspiring text of the historical literature on chemical garden was also made.
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10:50
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Bc.
Matouš
Pechar
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M2
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doc. Mgr. Fatima Hassouna, Ph.D.
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Physical stability of amorphous solid dispersion: computational study and experimental validation
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detail
Physical stability of amorphous solid dispersion: computational study and experimental validation
Many active pharmaceutical ingredients (APIs) are poorly water-soluble, which results in low bioavailability. A promising solution to this problem is the formulation of a so-called amorphous solid dispersion (ASD). ASDs typically comprise amorphous API molecularly dispersed in a polymeric carrier. However, the API tends to recrystallize if it is in a supersaturated state. Thus, knowledge of the API solubility in the polymer is important. The necessary solubility data is often acquired at elevated temperatures using differential scanning calorimetry (DSC) and then extrapolated using a solid-liquid equilibrium (SLE) model (e.g., the PC-SAFT equation of state (EOS)). An in silico approach that reliably models the API–polymer SLE curve can significantly reduce experimental efforts. Here, the compatibility of nifedipine (NIF) in a selection of polymers was screened using the PC-SAFT EOS. Next, the DSC-based protocol “step-wise dissolution” was followed to obtain solubility data for the modeled NIF–polymer binary systems. Finally, the performance of the PC-SAFT EOS was evaluated via comparison of the theoretical and experimental results. This cost and time effective strategy for API–polymer solubility determination may provide a dependable ASD design window for formulation scientists.
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11:10
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Bc.
Jan
Trnka
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M1
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Ing. Aleš Zadražil, Ph.D.
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Continuous Oscillatory Baffled Reactor for Production of Mesoporous Silica Microparticles
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detail
Continuous Oscillatory Baffled Reactor for Production of Mesoporous Silica Microparticles
Mesoporous silica has been lately investigated as a pharmaceutical excipient for drug formulation due to its exceptional ability to stabilise an amorphous state of poorly soluble API in its mesopores. However, industrial production of silica leads to particles of low specific surface area unsuitable for the drug formulation. Highly porous silica particles has been fabricated only in the batch to this day while a potential transfer to a continuous mode would result in more efficient and less expensive production of this excellent material.
This work aims to design a continuous reactor for mesoporous silica fabrication. A continuous oscillatory baffled reactor (COBR) was proposed for this purpose as the reaction is strongly dependent on mixing conditions. As the forming particles tend to attach to any solid surface, the deposition of the particles in the reactor is the ultimate problem. It was found that increasing the intensity of oscillations suppresses the particle accumulation in the reactor but leads to loss of particle quality. A perfect combination of system parameters as well as engineering insight is needed to overcome this problem and produce highly porous silica particles continuously with no deposition.
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11:30
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Bc.
Tetyana
Zheleznyak
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M1
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prof. Ing. Petr Kočí, Ph.D.
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Transient reaction kinetics on three-way catalyst during oscillations of gas composition
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detail
Transient reaction kinetics on three-way catalyst during oscillations of gas composition
A three-way catalyst is used to eliminate toxic compounds from exhaust gases produced by internal combustion engines. Its main functions are oxidation of hydrocarbons and carbon monoxide and reduction of nitrogen oxides. These reactions occur on catalytically active Pt, Pd and Rh nanoparticles dispersed in a thin layer on the monolith channel walls. To achieve complete conversion, gas composition must be stoichiometric and keep redox balance between oxidizing (O2, NOx) and reducing (CO, HC, H2) agents. Gas composition changes with air:fuel ratio in the engine that is controlled to meet the required stoichiometry. The composition oscillates during transient driving conditions, so the catalyst must be able to buffer temporary excess of reducing/oxidizing components. This is why ceria is added to the catalyst: it reversibly transforms from Ce2O3 to CeO2 to provide oxygen storage. In this work, a reaction kinetic model is developed that describes the catalyst’s response to dynamic changes in gas composition. Oxygen storage capacity and kinetic parameters for redox reactions are evaluated from lab experiments using different amplitudes and periods of oscillations. The developed kinetics improve the model’s accuracy and can be used to optimize catalyst operation in real conditions.
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