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.
Slavikova P.,Institute of Chemical Technology Prague |
Mudrova M.,Institute of Chemical Technology Prague |
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.
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.
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.