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Bratislava, Slovakia

In this contribution a generalized picture of the cavity number behavior is obtained by means of molecular dynamics simulations and consequent free volume analysis. The cavity number obtained for free volume cavities defined by different probe radii shows a complex behavior with the temperature. The number of cavities determined by small probes drops with the temperature. The number of cavities determined by large probes increases. This complex behavior of the cavity number can be discussed with the distinct behavior of the relative intensity, as observed in the experiment, and a support for the most basic of assumptions, that the cavity number relates to the relative intensity, is given.© (2013) Trans Tech Publications, Switzerland. Source


Markowska-Szczupak A.,West Pomeranian University of Technology | Ulfig K.,Polymer Institute | Morawski A.W.,West Pomeranian University of Technology
Journal of Advanced Oxidation Technologies | Year: 2012

The goal of the study was to examine the influence of TiO 2, indoor light and the photocatalytic process on the growth of Penicillium chrysogenum strains. An agar plate method with four fungal media (SGA, CYA, MEA, PDA) was used. The daily growth rates (mm × day -1) were calculated from the linear regression equation. In comparison to controls the TiO 2 addition to the media mostly inhibited fungal growth in the dark. The indoor light mostly decreased fungal daily growth rates both in controls and in media supplemented with TiO 2. The TiO 2 photocatalytic activity was observed for one strain on MEA (5 g TiO 2 × dm -3) and CYA (20 g TiO 2 × dm -3) and for another one on SGA (5 g TiO 2 × dm -3). The effects of TiO 2, light and photocatalytic reaction on fungal growth were found to be strain-and medium-dependent. © 2012 Science & Technology Network, Inc. Source


Danko M.,Polymer Institute | Micusik M.,Slovak Academy of Sciences | Omastova M.,Slovak Academy of Sciences | Bujdak J.,Slovak Academy of Sciences | And 2 more authors.
Chemical Papers | Year: 2013

New fluorescence dyes with an alkoxysilane moiety were synthesised by the condensation of 3-(triethoxysilyl)-1-propanamine (3-aminopropyltriethoxysilane) with 4,10-benzothioxanthene-3,1′-dicarboxylic acid anhydride (BTXA) and N,N-dimethylaminonaphthalene-1,8-dicarboxylic acid anhydride (DMANA), which was accompanied by the formation of an imidic bridge. The compounds N-(3-(triethoxysilyl)propyl)-thioxantheno[2,1,9-dej]isoquinoline-1,3-dione (BTX-S) and 4-(N′, N′-dimethyl)-N-(triethoxysilyl)propyl-1,8- naphthalene dicarboxylic acid imide (DMAN-S) were characterised by steady-state and time-resolved fluorescence spectroscopy in chloroform and ethanol. Both conjugates (BTX-S and DMAN-S) exhibited absorption and emission bands in the same region as the un-substituted BTXA and DMANA. An important Stokes shift was observed for DMAN-S in ethanol. A high fluorescence quantum yield was observed for BTX-S in both solvents and for DMAN-S in chloroform. In addition, the newly developed fluorescent silane dyes were covalently attached to the microscopic particles of layered silicates and on the surface of SiO 2 wafers as a proof of concept for fluorescence particle (surface) visualisation. The surface wafer modification was precisely characterised by X-ray photoelectron spectroscopy (XPS). Successful covalent linkage onto the particles of layered silicates was proved by confocal laser scanning microscopy technique. © 2012 Institute of Chemistry, Slovak Academy of Sciences. Source


Danko M.,Polymer Institute | Bures F.,University of Pardubice | Kulhanek J.,University of Pardubice | Hrdlovic P.,Slovak Academy of Sciences
Journal of Fluorescence | Year: 2012

The spectral properties of a novel type of Y-shaped fluorophores consisting of an imidazole ring end-capped with two electron-donating N,N- dimethylaminophenyl groups at positions C4 and C5 and one electron-withdrawing cyano group on the imidazole moiety at position C2 were examined. The π-linker separating the 4,5-bis[4-(N,N-dimethylamino) phenyl]-1H-imidazole donor moiety and the cyano group comprises 1,4-phenylene (1), (E)-phenylethenyl (2), (E)-phenyl-buta-1,3-dienyl (3), biphenyl (4), (E)-phenylethenylphenyl (5) and phenylethynylphenyl (6) conjugated paths. The absorption and fluorescence spectra were obtained in toluene, dichloro-methane, acetonitrile and methanol and in polymer matrices such as polystyrene (PS), poly(methyl methacrylate) (PMMA) and poly(vinylchloride) (PVC). The most intense absorption bands of fluorophores 1-6 were observed within the range of 283 to 330 nm. Less intense but longer-wavelength absorption bands designated as charge-transfer bands were observed at approximately 380-430 nm depending on the medium. The fluorophores exhibited strong fluorescence in the visible region with a Stokes shift of approximately 4300-5800 cm -1 in non-polar toluene and polystyrene, whereas very low intensity of fluorescence was observed with a Stokes shift in the 6500-7800 cm -1 region in polar methanol and acetonitrile. The large Stokes shift indicates a large difference in the spatial arrangement of the chromophore in the absorbing and emitting states. A relatively intense fluorescence (quantum yields of 0.12-0.69) was observed only for derivative 1 in all media except methanol. The fluorophores doped in matrices yielded more intense fluorescence compared with the fluorescence in liquid media. The use of solid polymer matrices lowers the probability of forming non-emissive excited states. The fluorescence lifetimes were short (1-4 ns) for all of the fluorophores in solvents and in polymer matrices. © Springer Science+Business Media, LLC 2012. Source


Omastova M.,Polymer Institute | Micusik M.,Polymer Institute | Fedorko P.,Slovak University of Technology in Bratislava | Pionteck J.,Leibniz Institute of Polymer Research | And 2 more authors.
Surface and Interface Analysis | Year: 2014

Multiwalled carbon nanotubes (CNT) were modified via the non-covalent approach using anodic surfactants dodecylbenzenesulfonic acid (DBSA) and poly(ethylene glycol) n-alkyl 3-sulfopropyl ether potassium salt and cationic surfactant cetyltrimethylammonium bromide (CTAB). These surfactants were used individually or as DBSA/CTAB mixtures. Surface modification was ultrasonically-assisted with a control over sonication power (64 or 360 W). The surface properties of modified CNT particles were determined by X-ray photoelectron spectroscopy and scanning electron microscopy. The electrical conductivities of unmodified CNT, particles treated by ultrasound, and CNT modified with surfactants were measured. Thermogravimetric analysis was used to determine the mass loading of surfactants after drying. The highest increase in conductivity was reached when CNT were treated solely with the anionic surfactant DBSA under the influence of soft ultrasound. This work shows conclusively that ultrasound-assisted modification of CNT by surfactants is a simple and efficient approach to prepare surface modified and highly conductive CNT, provided that physical (ultrasonic) and chemical (surfactants) treatments are concomitantly controlled. Copyright © 2014 John Wiley & Sons, Ltd. Source

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