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Investigation of Complexes of Tebuconazole with Zinc
Jakl, M. ; Norková, Renáta ; Navrátil, Tomáš ; Jaklová Dytrtová, Jana ; Balík, J.
Tebuconazole is one of the most utilized triazole pesticides in agriculture. Its stability is highly affected by complexation with metals. Moreover, it creates more or less stable complexes with essential elements that become unavailable to plants. In the system with overbundant tebuconazole, an inert (very stable) complex with Zn was found. Elimination voltammetry wit linear scan was used for revealing of the electrode processes on the mercury surface. The relatively slow kinetically controlled step in tebuconazole/Zn complex formation indication indicates the great ability of Zn-tebuconazole system to react with more ligans. Therefore, multiligand Zn-tebuconazole complexes with other ligands are expected in the nature.
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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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Monolayers at electrodes as basis for models of natural membranes
Josypčuk, Bohdan ; Mareček, Vladimír
Properties of thiol (HS(CH2)10COOH) monolayers were investigated at stationary electrodes based on silver, copper, bismuth and cadmium solid amalgams covered by a mercury meniscus or by a mercury film. For comparison, parallel experiments were performed at a classical hanging mercury drop electrode. Dependences of monolayer parameters on time of electrochemical deposition of thiol and on scan rate were performed. Statistical evaluation of all obtained results has confirmed that solid amalgam electrodes are a convenient tool for research of thiol layers.
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Electrochemical properties of thiol monolayers at surfaces of different electrodes
Josypčuk, Bohdan ; Mareček, Vladimír
Solid amalgam electrodes covered by a mercury meniscus or by mercury film (m-AgSAE, MF-AgSAE, m-CuSAE, m-BiAgSAE and m-CdSAE) are convenient for obtaining thiol films which are bound to different metals. By choosing an appropriate metal for the amalgam preparation, a thiol monolayer can be created which is stable in the given potential range. After a short accumulation time (1-2 min), the area of the reduction peak (charge) practically does not change it the monolayer is created from 1 nM thiol solution. Statistical results based on many times repeated formation and desorption of thiol monolayers (RSD = 2-3 %) attest that the stationary SAEs are convenient tools for study of electrochemical properties of thiol films.
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Studium transportu iontů přes modelové fosfolipidové membrány
Navrátil, Tomáš ; Šestáková, Ivana ; Mareček, Vladimír
Synthetically prepared model phospholipid bilayers (PLBs) in the form of black membranes, vesicles or supported membranes, with incorporated ionophores or real ion channels (i.e., artificially synthesized or gained from real living cells, e.g. protoplasts) are promising for study and simulations of transporting processes across the real cell membranes and the membranes surrounding sub-cellular structures. The electrochemical methods were found to be very suitable and sensitive enough for characterization of such processes.
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Cd and Pb Speciation in Thlaspi caerulescens Presl Rhizosphere
Jakl, M. ; Jaklová Dytrtová, J. ; Šestáková, Ivana ; Tlustoš, P.
In this study the influence of Thlaspi caerulescens Presl rhizosphere on Cd and Pb complex formation and their total amount in soil solution of contaminated fluvisol from Litavka river alluvium was investigated. The soil solution was sampled from roots surrounding and from bulk behind rhizobag. The content of free Cd and Pb ions was measured by the differential pulse anodic stripping voltammetry in unchanged pH and in pH 2 in rhizosphere and bulk soil. The bimetallic Cd-Pb-oxalic acid complexes were detected in unchanged pH only.
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