National Repository of Grey Literature 33 records found  previous11 - 20nextend  jump to record: Search took 0.00 seconds. 
Optimization and Mathematical Modelling of Hydrodistillation from Eucalyptus grandis and Lippia javanica
Topiař, Martin ; Sajfrtová, Marie ; Sovová, Helena ; Karban, Jindřich
K získání silice z rostlin Eucalyptus grandis a Lippia javanica sloužila hydrodestilace s použitím Clevengerova nástavce. Proměnnými parametry procesu byla doba varu, velikost částic a hydromodul. K vyhodnocení kinetických konstant hydrodestilace obou rostlin byl použit vhodný matematický model1, který počítá s rozdělením destilátu na dva podíly, kdy jeden je extrahován rychleji a druhý pomaleji, přičemž každému podílu přísluší vlastní kinetická konstanta. Mezi hlavní analyzované složky silice z eukalyptu patřil 1,8 cineol, alfa-pinen (8,2 hm. %), aromadenrden a spathulenol. Majoritní složky získané z výtažku lipie byly perillaldehyd, limonen a germacren. Bylo zjištěno, že optimálními parametry z hlediska maximalizace výtěžku jsou doba varu 5 h s poměrem navážka k objemu vody 1:5. Velikost částic nemá u zkoumaných rostlin zásadní vliv na velikost výtěžku. Maximální výtěžek eukalyptové silice dosahoval 26,7 mg/g, zatímco u lipie byl maximální výtěžek poloviční, a to 12,8 mg/g.
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29Si NMR Phenylsilane Polymer Analysis
Pinkas, Jiří ; Blechta, Vratislav ; Karban, Jindřich ; Sýkora, Jan
Here we focus on the analysis od dehydrocoupling polymerization reactions of phenylsilane. the molar mass distribution depends on the catalytic system and can be easily monitored by on-flow LC-NMR experiment.
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Effect of Conditions of Supercritical Fluid Extraction on Insecticidal Activity of Isolates from Rue
Sajfrtová, Marie ; Pavela, R. ; Karban, Jindřich
The aim of this study was to find optimal operating conditions of SFE from rue to obtain extract with maximal insecticidal activity. Several types of extracts were prepared using the benefit of variable solvent power of supercritical carbon dioxide. The extracts rich in volatile oil or oleoresin were obtained at 40 °C and 12 or 28 MPa, respectively. The extract enriched with polar components was extracted at pressure of 28 MPa and temperature of 40 °C with acetone added to CO2 as modifier (2.5 – 10 wt. %).
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Colloidal Silica as an Efficient Binder for the Preparation of Al-SBA-15 Pellets
Topka, Pavel ; Karban, Jindřich ; Soukup, Karel ; Jirátová, Květa ; Šolcová, Olga
The objective of this contribution was to examine the possibility of using colloidal silica as a binder for the preparation of extrudates or pellets from mesoporous molecular sieves. Al- SBA-15 pellets with different content of colloidal silica were prepared and their textural properties and mechanical stability were investigated. The catalytic activity of the pellets in Friedel-Crafts alkylation of toluene with benzyl alcohol was directly compared to that of binder-free pellets and powder catalyst.
Supercritical Fluid Extraction and Insecticidal Activity of Lamiaceae Plants
Sajfrtová, Marie ; Pavela, R. ; Karban, Jindřich ; Sovová, Helena
Natural insecticides based on bioactive extracts from plants represent a new trend in plant protection. Supercritical extraction (SFE) using CO2 is a modern extraction technique able to isolate high-added value compounds from plant without any thermal degradation, which allows to obtain extracts with high biological activity. In this work, insecticidal activity of SFE extracts from plant of mint family (Lamiaceae) has been studied and compared to activity of isolates obtained by conventional extraction techniques (hydrodistillation, organic solvent extraction). As a result of variation in extraction pressure, three types of extract were obtained: extract rich in volatile compounds (at 12 MPa), extract rich in oleoresins (at 28 MPa) and in polar compounds (5% of acetone used as modifier). Chemical composition and biological activity (LD50, antifeedant activity) of all isolates were evaluated and compared.
Utilization of Supercritical Fluid Extraction for Botanical Insecticide Isolation
Sajfrtová, Marie ; Sovová, Helena ; Karban, Jindřich ; Pavela, R.
The aim of this study was to compare the insecticidal activity of extracts obtained by SFE and traditional extraction methods from 20 plants. Three types of extracts were prepared using the benefit of variable solvent power of supercritical carbon dioxide. The extracts rich in essential oil or oleoresin were obtained at 50 °C and 12 or 28 MPa, respectively. The extract enriched with polar components was extracted at pressure of 28 MPa with ethanol added to CO2 as modifier. Essential oils were isolated from the herbs by hydrodistillation and oleoresins were obtained using Soxhlet extraction with liquid solvents. The biological activity of extracts was measured on different kinds of insect by means of contact toxicity test (LD50, LD90) and antifeedant activity. The insecticidal activity of the SFE products was compared with conventional extracts.
Hodnocení texturních, mechanických a katalytických vlastností pelet Al-SBA-15 s nízkým obsahem křemičitanového pojiva
Topka, Pavel ; Karban, Jindřich ; Soukup, Karel ; Šolcová, Olga
This contribution deals with evaluation on textural, mechanical, and catalytic properties of Al-SBA-15 pellets with low content of silica binder.

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See also: similar author names
1 Karban, Jan
1 Karban, Jaroslav
1 Karban, Jiří
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