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Preparation of Nanostructured Titania Thin Films Using Supercritical Carbon Dioxide
Cerhová, Marie ; Sajfrtová, Marie ; Matějová, L. ; Dřínek, Vladislav ; Daniš, S. ; Jandová, Věra
Extrakce čistým a modifikovaným superkritickým oxidem uhličitým (SFE) a extrakce podkritickou vodou byla využita k získání krystalických a čistých nanostrukturních tenkých filmů TiO2 a současně k odstranění organických prekurzorů ze syntézy solu sol-gel metodou. Při SFE byl sledován vliv teploty a použitého modifikátoru (vody, metanolu, etanolu a acetonu) na čistotu a mikrostrukturu tenkých filmů TiO2. Byl testován i kombinovaný postup extrakce, kdy se střídaly kroky s CO2 modifikovaným vodou a s CO2 modifikovaným organickými rozpouštědly. Čistota a krystalinita tenkých filmů byla zjištěna pomocí Ramanovy spektroskopie. Fázová složení a velikosti krystalů anatasu, žádané krystalické struktury, byly vyhodnoceny rentgenovou difrakční analýzou (XRD).
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22015111812130 - PDF
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Tailoring the Morphology of Microcellular Polymer Foams
Nistor, A. ; Rygl, A. ; Sajfrtová, Marie ; Toulec, M. ; Vonka, M. ; Kosek, J.
In this work, we focus on polymer foams with improved heat and/or sound insulation properties, in particular on microcellular foams with the cell sizes below 10 μm. By decreasing the cell size below 10 μm or even lower we can highly improve the foam heat and sound insulation properties. Depending on the foam structure (open-, closed-cell or dentritic) the foam application can vary. The structure-property relation is thus of great interest as well as the preparation of foams with various morphologies and scale-up of the manufacturing of microcellular foams.
Fulltext: content.csg - PDF
Plný tet: 115_nistor - PDF
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Comparison of Extraction Methods for Isolation of 20-Hydroxyecdysone from Leuzea carthamoides
Machalová, Zdeňka ; Sajfrtová, Marie ; Sovová, Helena ; Bártlová, Milena
This work is focused on the extraction of 20-HE from roots and seeds of Leuzea carthamoides using SFE, PLE and Soxhlet extraction. The SFE and PLE conditions (pressure, temperature, type and concentration of solvent, extraction time) were optimized to improve extraction yields and concentrations of 20-HE in extracts. These methods were compared with a conventional Soxhlet-type extraction. The SFE experiments were carried out at temperatures from 40°C to 60°C, pressures from 30 to 65 MPa and with addition of 5-20% of co-solvent (ethanol, methanol and acetone). PLE with ethanol, methanol and acetone was made at temperatures from 70°C to 100°C, pressures from 7 to 20 MPa and extraction time from 5-15 min. Soxhlet extraction with ethanol was used to evaluate the total content of 20-HE in roots and seeds. The concentration of 20-HE in extracts was determined by HPLC.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22014082908303 - PDF
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Preparation and Characterization of Micro- and Nanocellular Polystyrene Foams
Nistor, A. ; Rygl, A. ; Sajfrtová, Marie ; Bobák, M. ; Kosek, J.
Polystyrene foams with closed cells were prepared using supercritical CO2 as the blowing agent. On the other hand, polystyrene foams with open cells were prepared via temperature induced phase separation, namely by the spinodal decomposition. In both cases, we systematically studied the influence of the foaming conditions (focusing especially on nucleation and coalescence) on the final foam morphology. The influence of solvent residua on foaming was discussed in. By carefully optimizing the foaming conditions we prepared foams with an average cell size below 1 μm. Furthermore, we studied the heat insulation properties of the prepared foams and compared them with the results of heat transport simulation in foams.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22014090110372 - PDF
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Extraction Kinetics and Insecticidal Activity of Volatile Components Isolatedfrom rue by Supercritical CO2.
Sajfrtová, Marie ; Karban, Jindřich ; Sovová, Helena ; Pavela, R.
The aim of the work was to describe the SFE of volatile components from rue and to analyse their insecticidal effects. The objectives consisted in: (a) optimizing the SFE condition (pressure, temperature, extraction time, use of additional separator and concentration of modifier in CO2),investigating their effect on the yield, concentration volatiles in extract and the insecticidal activity, determination of the SFE kinetics of major components in the rue extracts and comparing the SFE with hydrodistillation and maceration.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22014090110391 - PDF
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