|
| |
|
| |
|
| |
|
| |
|
|
Preparation and Characteristics of Porous Supports for Microporous Membranes Based on Al2O3 and SiO2
Fíla, V. ; Hrabánek, Pavel ; Juristová, K. ; Zikánová, Arlette ; Andertová, J. ; Bernauer, B.
Inorganic membranes have been used for separation of various liquid and gas mixtures due to their high mechanical and chemical resistance at elevated temperatures and pressures. The materials such as stainless steel, ceramics, polymers are available for preparation of the inorganic membranes. This paper is focused on the preparation and characterization of the composite membranes consisting of a ceramic support and layer of zeolite. The first part of the paper deals with the preparation of the porous ceramic supports, which are made using dry molding of a ceramic suspension mixed with the organic dispersant. The supports were characterized by permeation of N2, mercury porosimetry and SEM. The second part of the paper is focused on the preparation of microporous zeolite (MFI) layers on the supports. These microporous membranes were characterized by permeation and separation of H2 and iso-butane.
|
|
|
Recyclation and Transformation of Homocysteine as a Part of Detoxication Processes in the Cell
Přistoupilová, K. ; Přistoupil, T. ; Šenholdová, Z. ; Navrátil, Tomáš ; Heyrovský, Michael
The presented metabolic pathways explain how the transformation of homocysteine affects the detoxication processes in the human cell. On the one hand homocysteine is recycled to methionine; on the other hand it is transformed to cysteine. Both pathways are connected by B12 vitamin. Their relation to the thiodiglycolic acid (TDGA), which represents a part of the detoxication processes, is demonstrated on the scheme. The changes in TDGA concentration in urine were found to depend on the changes in redox equilibria (of vitamin B12, folic acid, homocysteine). Key Words: Thiodiglycolic acid, TDGA, vitamin B12, folic acid, metabolic pathways, homocysteine, detoxication.
|
|
|
Změny koncentrace TDGA v moči jako možný marker metabolismu thiosloučenin
Přistoupilová, K. ; Přistoupil, T. I. ; Šenholdová, Z. ; Navrátil, Tomáš ; Heyrovský, Michael ; Fenclová, Z.
The new simple voltammetric method we described recently, proved already to be useful in determining thiodiglycolic acid (TDGA) levels in urine samples of people influenced by some chemicals, victuals and pharmaceuticals. The present pilot study is a continuation of our previous work devoted to test general feasibility of the method. We concentrated upon time dependent quantitative changes of TDGA excretion into urine of selected volunteers. The TDGA level in all morning samples was the highest in comparison with samples collected during the day. The TDGA level was dependent on the health condition of each person involved. However, a further marked increase of TDGA in the morning urine was observed individually, in general when vitamin B12 had been administered in the evening the day before. Vitamin B12 is known to play an important role in the metabolism of one- and two-carbon units, of homocysteine and of sulfhydryls in general. Certain differences in excretion course of TDGA.
|
|
|
Pohlaví vytvořila příroda, ale překážky vytvořil člověk
Heyrovská, Rajalakshmi
Nature created men and women supplementary to each other, with a constant sum total of physical and mental abilities. Men who have more of the former consider women as weaker and are thus blind to women's capabilities, which they in fact can enjoy! Since men cannot do without womens abilities, we women have to open their eyes!
|
|
|
Vývoj anorganických nosičů vhodných pro depozici mikroporésních vrstev – syntéza a charakterizace
Juristová, K. ; Fíla, V. ; Andertová, J. ; Zikánová, Arlette ; Bernauer, B. ; Lhotka, M.
The present study is focused on the preparation of porous supports (ceramic, glass) and thin microporous layers (zeolite, polyaluminum chlorid (PAC), silicalite-1), which are suitable for application in the catalysis, membrane technology and biotechnology. The modification of ceramic Al2O3 support and its preparation by the slip-casting method is discussed here. The optimal conditions for modification of ceramic support using the PAC and the optimal conditions for slip-casting support design were proposed and experimentally verified. The second part of the work deals with the synthesis of boro-silicalite glass. The characterization of the supports by SEM, mercury porosimetry and by permeation measurements are discussed.
|
|
|
Kompozity na bázi silikalit-1- polyimidy
Šnáblová-Fryčová, M. ; Sysel, P. ; Chánová, E. ; Bernauer, B. ; Kočiřík, Milan
Two methods of adhesion improvement between the polyimide matrix and zeolite (silicalite-1) were examined. Firstly, there were prepared polyimide precursors (polyamic acids) with controlled molecular weight terminated with 3-aminopropyltriethoxysilane. The transformation of polyamic acids into polyimides upon heating was accompanied by the formation of Si-O-Si bonds between the polymeric matrix and hydroxyl groups on zeolite surface. Secondly, the polyimide was modified using rubbery poly(dimethylsiloxane)s. Relations between film properties (i.e. interfacial adhesion and accessibility of zeolite channels for species) and film composition were studied both for unfilled and filled PI films.
|
guest ::
RSS feed.