National Repository of Grey Literature 178 records found  previous11 - 20nextend  jump to record: Search took 0.09 seconds. 
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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Mass Transport Simulation in Replicas of Porous Material: Effective Transport Properties Estimation
Čapek, P. ; Veselý, M. ; Kolafa, J. ; Hejtmánek, Vladimír ; Brabec, Libor
The purpose of this study was calculation of transport properties of the replicas of some macroporous materials. These trasport parameters such as the effective permeation or diffusion coefficient, respectively, were compared with their experimentally measured counterparts.
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Artificial phospholipid membranes as models of real membranes and transport of charged particles across them
Parisová, Martina ; Navrátil, Tomáš ; Šestáková, Ivana ; Kohlíková, E. ; Petr, M.
Because the real bio-membranes and the tranporting processes realized across them are very complicated, the model membranes have been used for elucidation of the basic transporting steps. In the contribution, the different possibilities of characterization, description, and elucidation of the transport processes on the example of some metal ions and theor complexes, i.e., of cadmium, lead, and copper, were presented. It summarizes the results achieved using supported phospholipid model membranes formed on porous membranes and on agar support. Discussed transporting processes of selected ions have been characterized using two electrochemical methods: electrochemical impendance spectrometry (EIS) and voltammetry. The impact of some parameters on these systems and processes was investigated.
Electroanalysis with phthalocyanine modified HOPG electrodes
Mansfeldová, Věra ; Janda, Pavel
In this papers we presented modification of highly oriented pyrolitic graphite (HOPG) by two different phthalocyanine (Pc) derivatives and two different deposition techniques. We have investigated electrode modified by fullerene-derived phthalocyanine and cobalt tetraneopentoxyphthalocyanine (CoTNPc) to consider how different modification procedure-electrodeposition and drop evaporation and composition of phthalocyanine influences detection of model compound, L-cysteine.
Properties of some radiosensitizers studied by means of the electrochemical methods
Gál, Miroslav ; Kolivoška, Viliam ; Ambrová, M. ; Híveš, J. ; Sokolová, Romana ; Hromadová, Magdaléna
To determine the correlation between reduction potential and some physicochemical properties of selected radiosensitizers cyclic voltammetry and theoretical calculations based on the DFT method with B3LYP functional of the level of 6-311++G** basis set in vacuum were utilized. Very good correlation was found between electron affinities of radiosensitizers and their reduction potential and so called E1(7) potential.
Electrochemical and spectrometric study of FOX-7 in aprotic solvents
Šimková, Ludmila ; Ludvík, Jiří ; Klíma, Jiří
2,2-Dinitroethene-1,1-diamine (FOX-7) is a recently developed and broadly tested energetic material with high efficiency and low sensitivity. Generally, explosion is based on thermally initiated chain of intramolecular redox reactions. Recently it has been found that electrochemical reduction in aqueous solutions is also able to provoke the chain of follow-up processes leading to total decomposition of the parent substance yielding gaseous products analogously like during explosion. Similarly, results from reductive electrolysis of FOX-7 in aprotic solvents show analogous course of degradation. The first transferred electron activates the molecule and initiated the formation of colored radical intermediates that have been spectroscopically characterized
Utilization of electrochemical methods in studies of transporting processes across the phospholipid bilayers
Navrátil, Tomáš ; Šestáková, Ivana ; Mareček, Vladimír
This contribution deals with studying and characterization of transporting processes of heavy metals (lead and cadmium) in the form of their free ions and of their complexes with small organic ligands across biological membranes. These membranes are represented by model phospholipid bilayers, formed on the surface a suitable flat support material or in its pores. Phosphatidyl choline and phosphatidyl ethanolamine were used as the membrane building elements. Voltammetry and electrochemical impendance spectrometry (EIS) have been used for characterization of the transporting processes.
Voltammetric determination of anticancer drug flutamide at screen-printed carbon electrodes
Vyskočil, V. ; Navrátil, Tomáš ; Barek, J.
Flutamide, 4-nitro-3-trifluoromethyl-isobutylanilide, is the active component of a synthetic nonsteroidal antiandrogen drug, which is commonly used in the treatment of advanced prostate cancer. In this contribution, optimum conditions have been found vor voltammetric determination of flutamide by DC voltammetry (DCV) and differential pulse voltammetry (DPV) at screen-printed carbon electrodes (SPCEs). Under optimum conditions (Britton-Robinson buffer pH 7.0 - methanol (9:1)), linear calibration curves were measure with limits of quantification 6x10(-7) molL(-1) and 8x10(-7) molL(-1) for DCV at SPCEs, respectively. The newly developed methods were successfully applied to the determination of the drug in pharmaceutical formulation Apo-Flutamide (Eulexin tablets).
Determination of phytohormones in genetically modified Nicotiana plants by differential pulse voltammetry
Kocábová, Jana ; Sokolová, Romana ; Giannarelli, S.
The differential pulse voltammetry was used for the determination of the phytohormone indole-3-acetic acid (IAA) in plant samples using a glassy-carbon electrode. The limit of detection of the proposed method is 0,45 microg.ml-1. The electrochemical determination of IAA is selective and the concentration of IAA in sample of genetically modified plant Nicotiana langsdorfii was determined in the presence of other phytohormones as abscisic acid and some cytokinins.
Bioimpedance methods to measure somatometric and volumetric changes
Petr, M. ; Kohlíková, E. ; Navrátil, Tomáš
Assessment of human body composition has stimulated the need for an understanding of available methodologies of estimating fat free mass and percent body fat. In our study, we found statistical significant changes of body composition evaluated by multi-frequency bioelectrical analysis in a group of athletes following creatine supplementation. These results are consistent with literature i.e. supplemented creatine effects osmolality of cell´s membranes which leads to increased intracellular water retention. Multi-frequency BIA can be considered to be an accurate and sensitive method for assessment of human body composition.

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