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Kokaislova A.,Technicka | Parchansky V.,Czech Institute of Organic Chemistry And Biochemistry | Matejka P.,Institute of Chemical Technology Prague
Journal of Physical Chemistry C | Year: 2015

Nicotinic acid and pyridoxine, adsorbed on electrochemically prepared copper substrates, were studied by Surface-Enhanced Infrared Absorption (SEIRA) spectroscopy. Assignment of the bands in SEIRA spectra to appropriate vibrational modes was based on results of DFT calculations. The role of dissolved gas in deposition solution was elucidated for adsorption of nicotinic acid. Temperature dependence of SEIRA spectral features of both nicotinic acid and pyridoxine was studied in the temperature range 15-50 °C. In order to evaluate the temperature-induced changes of SEIRA spectra of both two adsorbates, the bands were fitted with Voigt profiles and their heights and widths were compared. Principal Component Analysis (PCA) and Partial Least Squares (PLS) regression were applied. It was found out that heating even to 50 °C does not induce any observable changes in molecular structure of adsorbates. However, noticeable changes of band intensities and widths were detected and assigned to the partial reorientation of adsorbed molecules, to the changes of intermolecular interactions within the adsorbed layers, and to a minor extent, to the other changes of metal-adsorbate systems properties, for example, to the changes of surface moisture. The changes of metal reflectivity are considered to be the minor source of spectral variation. © 2015 American Chemical Society.


Korinek R.,Kolejni | Korinek R.,Academy of Sciences of the Czech Republic | Vondrak J.,Technicka | Bartusek K.,Kolejni | And 2 more authors.
Journal of Solid State Electrochemistry | Year: 2013

In this article, the properties of gel electrolytes based on the NaClO 4 inorganic salt are described. For electrolytes with various concentrations of inorganic salts, relaxation times T 1 and T 2 were measured by means of MR techniques at regular intervals during the polymerization. To measure relaxation time T 1, the inversion recovery (IR) technique was used. The measurement of relaxation time T 2 was performed using the spin-echo (SE) technique. The reduction of relaxation times during the polymerization, namely, T 1 from the value of 5.5 to 1.7 ms and T 2 from the value of 5.5 to 1 ms, indicates a change in the internal structure of the gels and a change in their chemical composition. The waveforms measured will contribute to further studies of gel electrolytes aimed at increasing their electrical conductivity and establishing the influence of water molecules on the conductivity. © 2012 Springer-Verlag.


Nasswettrova A.,Brno University of Technology | Drexler P.,Technicka | Seginak J.,Technicka | Nespor D.,Technicka | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

The authors discuss the application of a broadband noise signal in the research of periodic structures and present the basic testing related to the described problem. Generally, noise spectroscopy tests are carried out to verify the behaviour of the response of periodic structures, and the related objective consists in recording the properties of microscopic structures in natural and artificial materials. The aim is to find a metrological method to investigate structures and materials in the frequency range between 100 MHz and 10 GHz; this paper therefore characterizes the design of a suitable measuring technique based on noise spectroscopy and introduces the first tests conducted on a periodic structure. In this context, the applied instrumentation is also shown to complement the underlying theoretical analysis. © 2015 SPIE.


Martinasek Z.,Technicka | Clupek V.,Technicka | Trasy K.,Technicka
2015 38th International Conference on Telecommunications and Signal Processing, TSP 2015 | Year: 2015

Acoustic side channel belongs to one of the oldest side channel and currently, the acoustic attacks are focused on computer keyboards, automated teller machine and internal computer components. Different methods are used for a classification of acoustic traces measured. It primary depends on the fact if the attacker processes the measured data in time or frequency domain. These two approaches use mostly neural networks connected to dictionary using hidden Markov models for an improvement of classification results. We decided for a compromise between the time and frequency domains and we process acoustic trace measured in the time-frequency domain by using a spectrogram. We use the spectrogram as an input of a typical two-layer neural network with the back propagation learning algorithm. This approach is based on a simple algorithm and does not use any other tool to improve classification results. We used widely available laptop with an integrated microphone placed in an office to analyze the potential repeatability and feasibility of the proposed method. © 2015 IEEE.


Martinasek Z.,Technicka | Malina L.,Technicka | Zeman V.,Technicka
2015 38th International Conference on Telecommunications and Signal Processing, TSP 2015 | Year: 2015

The paper deals with the scalable authentication schemes for a integration server. The integration server is essentially a cloud system and provides services to the users according to the model Software as a service. Our goal is to propose a new authentication solution for special devices that are accessing to the server. These devices represent mostly computationally limited devices such as Electronic security systems (ESS) and Fire Alarm Systems (FAS). The proposed solution ensures authentication, confidentiality and the integrity of transmitted data. We have proposed the solution of three basic authentication schemes which are based on a challenge-response mechanism. The proposed schemes are denoted as light authentication, middle authentication and robust authentication. The schemes differ in security, computational and complexity. Moreover, we have implemented our proposals as a proof-of-concept application and we have tested this solution. © 2015 IEEE.


Holan J.,Technicka | Skorepova E.,Institute of Chemical Technology Prague | Heraud L.,Sanofi S.A. | Heraud L.,ENSIACET | And 5 more authors.
Organic Process Research and Development | Year: 2016

Polymorphism is of great interest to the pharmaceutical industry because polymorphs have different physicochemical properties such as dissolution rate. In the present work, the influence of process conditions on the polymorphic antisolvent crystallization and transformations during cooling crystallization of agomelatine metastable form X from water/methanol solution has been investigated with a view of designing a robust process that includes not only crystallization but also filtration, filter cake washing, and drying. The competitive stability method was used in order to identify regions of the parametric space (water/methanol ratio, process temperature, and initial concentration) in which the crystallization of form X can be feasible. The formation of agomelatine form X was confirmed by subsequent kinetic experiments. The influence of process parameters such as the intensity of agitation, the antisolvent addition rate, and the precipitation temperature on the yield and particle size of the crystalline product was also investigated. The batch antisolvent crystallization of the metastable form X was monitored using in-line Raman spectroscopy and FBRM probe, and the type of the resulting polymorph has been confirmed by X-ray powder diffraction (XRPD). Finally, the effect of the obtained crystals of metastable form X on downstream operations-namely, filtration and drying-has been studied. © 2015 American Chemical Society.


Holubova B.,Technicka | Cilova Z.Z.,Technicka | Kucerova I.,Institute of Chemical Technology Prague | Zlamal M.,Institute of Chemical Technology Prague
Progress in Organic Coatings | Year: 2015

Currently, there is a growing interest in the application of silicon-based technologies for the development of advanced hybrid organic-inorganic coatings with strong weatherability. In this study, the sol-gel process is used to prepare such coatings on glass and their resistance to weathering effects is assessed afterwards. Various sols were prepared by mixing a silica-based inorganic matrix (tetraethyl orthosilicate) with different quantities of silica alkoxides functionalised with various organic groups. Subsequently, the sols were dip-coated onto glass samples at low temperatures without any heat treatment. The coatings prepared were analysed before and after three model ageing tests simulating various weathering parameters. After ageing, the best performing coatings showed good overall homogeneity and transparency (optical microscopy, SEM), improved water repellency and adhesion to the glass substrate (static contact angle measurements, cross-cut tape tests) and no colour or chemical composition changes (UV-VIS, FTIR). Compared with commercial hybrid silica products, the alkyl- and methacryloxy-functionalised silica coatings particularly displayed improved homogeneity, elasticity and barrier properties. Thus, these low temperature coatings, easily applicable to thin films, appear to fulfil the main requirements for the protection of the glass exposed to weathering phenomena. © 2015 Elsevier B.V. All rights reserved.


Szabo Z.,Technicka | Drexler P.,Technicka | Seginak J.,Technicka | Nespor D.,Technicka | And 3 more authors.
Progress in Electromagnetics Research Symposium | Year: 2015

The authors discuss the application of a broadband noise signal in the research of periodic structures and present the basic testing related to the described problem. Generally, noise spectroscopy tests are carried out to verify the behaviour of the response of periodic structures, and the related objective consists in recording the properties of microscopic structures in natural and artificial materials. The aim is to find a metrological method to investigate structures and materials in the frequency range between 100 MHz and 10 GHz; this paper therefore characterizes the design of a suitable measuring technique based on noise spectroscopy and introduces the first tests conducted on a periodic structure. In this context, the applied instrumentation is also shown to complement the underlying theoretical analysis.


Slavikova P.,Institute of Chemical Technology Prague | Mudrova M.,Institute of Chemical Technology Prague | Moravec H.,Technicka
Mendel | Year: 2013

Kriging is a proved and commonly used computational method in geological research based on probability. Presented project transfers this approach to image processing and studies application to nanotubes. Results are compared with Otsu's method.

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