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Insect cold tolerance and seasonal changes in composition of sterols and tocopherols
URBAN, Tomáš
Presented work focused on researching cold resistance in insects (Pyrrhocoris apterus), especially in qualitative and quantitative composition and seasonal changes in the content of tocopherols and sterols in membranes. Collection of samples, tissue extraction, separation, sample preparation and the final analysis was included. There were detected three different sterols (animal cholesterol, plant sterols: campesterol and sitosterol). Also were detected ?-tocopherol and ?-tocopherol. Volume of cholesterol was in the range of 0.2 to 0.8 mol%, for phytosterols was the range from 1.2 to 15.2 mol%, and for tocopherols was the range from 0.1 to 31.3 mol%. Seasonal fluctuations of sterols and tocopherols were evaluated with a minimum in summer and maximum in winter.
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Transport of divalent cations across the gel supported phospholipid membranes
Navrátil, Tomáš ; Šestáková, Ivana ; Mareček, Vladimír
This contribution deals with elucidation of principles of transporting processes of heavy metals (mainly lead, cadmium) across the biological membranes. The real membranes were for purposes of described experiments, replaced by model membranes, which were composed of phospholipid bilayers. Two different phorpholipids (1,2-dipalmitoyl-sn-glycero-3-phosphocholine and the mixture of phospholipids obtained from soybeans (under commercial name Asolectin)) were used as the building elements for the formation of these membranes on the surface of the constructed gel electrode. The registered transporting processes have been characterized using voltammetry, and electrochemical impendance spectrometry (EIS). The impact of some parameters on these systems and processes was investigated.
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Purification of Biogas by Means of Membranes
Poloncarzová, Magda ; Vejražka, Jiří ; Izák, Pavel
The aim of this work is to find a way to lower carbon dioxide concentration in biogas and to purify it from undesirable gases by means of membrane. Ideally only one or two steps should be used to make the technology feasible and profitable. Liquid membranes are used because of their high selectivity and good permeability. Successful biogas purification method would open new opportunities in ecological fuels, especially if the methane content in biogas reached more than 95%; biogas could then replace the natural gas. In this work, a new supported ionic liquid has been tested and the first results have been obtained. Sweeping gas permeation was performed with model mixture of CO2 and CH4 1:1.
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Transport of cadmium ions across model supported phospholipid membranes
Navrátil, Tomáš ; Šestáková, Ivana ; Mareček, Vladimír ; Štulík, Karel
These results report on experiments focussed on the formation of supported model phospholipid membranes, formed from phosphatidyl choline in the micrometric pores of hydrophilic polycarbonate supports, their chatacterization using voltammetry and electrochemical impendance spectrometry (EIS). Attention was paid transport of heavy metal ions (ions of cadmium, etc.) across these membranes in the presence or absence of ionophores (valinomysing and calciomycin) or in the presence of oxalic acid. The impact of some parameters on these systems and processes was investigated.
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Preparation of silicalite-1 composite membranes
Hrabánek, Pavel ; Bernauer, B. ; Zikánová, Arlette ; Krystl, V. ; Kočiřík, Milan
Silicalite-1 crystal layers were synthesised on stainless steel and ceramic supports. The stainless steel supports manufactured by Trumem Int. (USA) and ceramic supports manufactured by Carborundum Electrite (Czech Republic) were chosen to prepare silicalite-1 composite membranes. In the case of stainless steel silicalite-1 composite membrane, the applied synthesis process has been recently developed by Gora et.al [1]. It was observed that the presence of silicalite-1 seeds influenced the membrane quality. A number of crystallization steps also played an important role. Ceramic silicalite-1 composite membranes were prepared on ceramic supports with the layers of randomly oriented silicalite-1 crystals. The disadvantage of the ceramic supports was their large pore size distribution and roughness of the surface. For this reason, several coating steps using ceramic glaze had to be used to reduce the pore size distribution and non-uniformity of the surface.
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