Ustav fyziky a merici techniky

Prague, Czech Republic

Ustav fyziky a merici techniky

Prague, Czech Republic
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Prusova P.,Ustav konzervace potravin | Kruzik V.,Ustav konzervace potravin | Seidl J.,Ustav fyziky a merici techniky | Cizkova H.,Ustav konzervace potravin
Chemicke Listy | Year: 2017

Measuring electrical impedance enables characterisation of the studied matrix non-invasively and in real time. Our work was aimed to verify the method of electrochemical impedance spectroscopy for quick confirmation of orange juice authenticity. For the purpose of the experiment, the tested samples of orange juice were diluted with water and enriched by sugars and citric acid, as this type of adulteration and the chosen concentrations of the added substances correspond to the most likely means of misleading customers in the case of fruit juice. The analysis of the electrochemical parameters of the tested samples was carried out in an impedance cell with planar electrodes at a voltage of 0.5 V and the frequency ranging from 50 Hz to 1 MHz. The results of the measurements show that the method enables quick and simple screening of the quality of orange juice made from concentrate; more specifically, it enables one to detect dilution of 100 % juices with 20 or more per cent of water or the sugar addition. As such, the method can be recommended as another procedure of consumer protection and prevention of unfair competition among manufacturers. © 2017, Czech Society of Chemical Engineering. All rights reserved.


Vrnata M.,Ustav fyziky a merici techniky | Kopecky D.,Ustav fyziky a merici techniky | Skodova J.,Ustav fyziky a merici techniky | Fitl P.,Ustav fyziky a merici techniky | And 2 more authors.
Chemicke Listy | Year: 2012

The increasing application of conductive polymers in electronics requires a precise and controlled deposition of these materials in thin layers. The article provides a brief description of the method, the principle and properties of both the source polymer and the matrix; also the experimental conditions necessary for successful thin layer preparation are presented. Matrix-assisted pulsed laser evaporation of polypyrrole was carried out at different laser fluences (0.1-0.6 J cm-2) with KrF excimer laser (λ = 248 nm) from water and dimethyl sulfoxide matrices - and also with Nd:YAG laser (λ = 266 nm) for comparison. The layer thickness was hundreds of nanometers. The relations of the laser wavelength, laser fluence and the used matrix on the one hand and chemical composition of the layers (analyzed by FTIR) on the other were studied. The ablation threshold was 0.25-0.30 J cm-2 for dimethyl sulfoxide matrix.


Kopecky D.,Ustav fyziky a merici techniky | Vrnata M.,Ustav fyziky a merici techniky | Kopecka J.,Ustav fyziky a merici techniky
Chemicke Listy | Year: 2015

This review deals with four major laser deposition technologies (pulsed laser deposition, matrix assisted pulsed laser evaporation, laser induced forward transfer, matrix assisted pulsed laser evaporation – direct write), used for depositions of organic materials in both vertical (thin films) and horizontal structures (with high-resolution motives). Each technology is described in terms of the principle and its capability of nondestructive depositing polymers and biological materials. The influences of the used deposition methods on chemical composition and morphology of the deposited material. Using the laser deposition technologies for organic materials is still considered an alternative to the conventional methods. The aim of this review is to show that laser deposition technologies can in many respects overcome the conventional technologies and serve well the needs of new, progressive trends in the chemistry, material science and electronics. © 2015, Czech Society of Chemical Engineering. All rights reserved.

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