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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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The Effects of Agitated Beds Homogenization on Stirrer Geometry and Bed Depth via DEM
Kohout, M. ; Trávníčková, Tereza ; Havlica, Jaromír
In this contribution open source DEM particle simulation software LIGGGHTS was studied and tested. Collision forces are there modelled by the softsphere approach with the Hertzian collision model. As an application we studied agitated particle beds (packed from glass spherical particles of two colours – packed vertically and horizontally) mixed by different types of agitators. Dependence of degree of homogenization on particle diameter, particle properties (Young’s modulus), and on geometrical aspects (bed depth, agitator position, etc.) will be also discussed.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22014090110404 - PDF
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Granular Dynamics of the Mixing Processes for Different RPM Using DEM
Jirounková, K. ; Havlica, Jaromír ; Kohout, M.
This paper emphasizes on the computer simulations of the granular materials via Discrete Element Method (DEM) by using open-source software LIGGGHTS. The examined process was mixing of two granular materials distinct by colour. The different initial conditions have led to finding the best way of homogenization, but it also shows the new perspective of noticing the process as a system of inseparable processes linked to each other.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22014090110403 - PDF
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Sorption Ceramic Membranes with a Functionalized Surface Layer
Zub, Yu.L. ; Tomina, V.V. ; Melnyk, I.V. ; Stolyarchuk, N.V. ; Nazarchuk, H.I. ; Sliesarenko, V.V. ; Sliesarenko, V.M. ; Topka, Pavel ; Šolcová, Olga
In the current work, we have considered and compared the deposition on the surface of ceramic membrane of the polysiloxane layers with different functional groups, such as ≡Si(CH2)3SH, ≡Si(CH2)3NH2, and ≡Si(CH2)2P(O)(OH)2, and ≡Si(CH2)3NHC(S)NHC2H5. We have also reported the fabrication of ceramic membranes with bifunctional polysiloxane surface layers, containing two types of complexing groups of different nature, or (fluoro)alkyl groups along with complexing groups. Tetraethoxysilane and bis(triethoxy)silane structuring agents were used in the study. The identification of the deposited layers on the membrane surface was carried out by IR spectroscopy. It was shown by SEM, that the functionalized layers themselves are usually formed by 50-70 nm nanoparticles and their porous structure depends on several fabrication factors.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22014090110370 - PDF
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CFD Model of HDS Catalyst Tests in Trickle-Bed Reactor
Tukač, V. ; Prokešová, A. ; Hanika, Jiří ; Zbuzek, M. ; Kubička, D.
The goal of this study was to evaluate hydrodynamic influence on experimental HDS catalyst activity measurement carried out in pilot scale trickle-bed reactor. Hydrodynamic data were evaluated by RTD method in laboratory glass model of pilot reactor. Mathematical models of the process were formulated both like 1D pseudohomogeneou and 3D heterogeneous ones. The aim of this work was to forecast interaction between intrinsic reaction kinetic, hydrodynamics and mass transfer.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22014090110405 - PDF
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