Meitingen, Germany
Meitingen, Germany

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Jokanovic V.,Vinča Institute of Nuclear Sciences | Vilotijevic M.,Vinča Institute of Nuclear Sciences | Jokanovic B.,SGL Carbon | Jenko M.,Slovenian Institute of Metals And Technology | And 5 more authors.
Corrosion Science | Year: 2014

In this research, the structure changes along the depth of gradient layers of titanium substrate, after etching with NaOH and subsequent thermal treatment at various temperatures between 300 and 800°C, were investigated by XRD, FTIR and AES. Particularly, the changes of Ti substrate after etching with NaOH, subsequent ionic exchange of Na+ with Ca2+ ions and thermal treatment at 700°C were analysed. Due to this approach, it was possible to get insight into the chemical changes and changes of Ti oxidation states and consequent phase analysis, along the depth of the titanium oxide coatings. In addition, Secondary Electron Imaging (SEI) showed very interesting nanotopology of all samples. Particularly interesting topology, consisting of very thin nano-designed walls between mutually interconnected pores, was observed for the sample in which Na+ were replaced with Ca2+ ions. This structure might be suitable for deposition of hydroxyapatite by biomimetic or plasma methods and as an appropriate scaffold for cell adhesion and proliferation. © 2014 Elsevier Ltd.


Jokanovic V.,Vinča Institute of Nuclear Sciences | Colovic B.,Vinča Institute of Nuclear Sciences | Jokanovic B.,SGL Carbon | Rudolf R.,University of Maribor | And 2 more authors.
Journal of Biomedical Materials Research - Part A | Year: 2014

The SiO2 thin films (STFs) were deposited on the surfaces of stainless steel tapes and their activity was particularly investigated from the aspect of the number density of hydroxyl groups on their surfaces. The calculation procedure of density of active OH groups includes determination of average length of silica chains that constitute silica sol particles with almost uniform size, on the base of thermogravimetric analysis. The size of SiO 2 particles is analyzed by transmission electron microscopy and dynamic light scattering method. Fibroblast (L929) cell densities on the surfaces of these films were investigated using phase contrast microcopy. It was shown that there is a relationship between OH group densities and density of attached cells. Besides, the cytotoxicity effect was studied and compared for various thermally treated STFs. © 2013 Wiley Periodicals, Inc.


Jokanovic V.,Vinča Institute of Nuclear Sciences | Colovic B.,Vinča Institute of Nuclear Sciences | Jokanovic B.,SGL Carbon | Zivkovic S.,University of Belgrade
International Journal of Applied Ceramic Technology | Year: 2015

The aim of this study was to synthesize and characterize new superplastic endodontic mixtures (named as ALBO-MPSA) with strongly accelerated hydration rate. Two different ALBO-MPSA mixtures were prepared using combination of hydrothermal and high-temperature self-propagating method. Phase analysis of the mixtures, before and after hydration, was carried out by X-ray diffraction (XRD), while morphological analysis was performed by scanning electron microscopy (SEM). Investigations of mechanical properties showed that new superplastic, quick-bonding endodontic mixtures with good mechanical properties were obtained (compressive strength after 28 days aging was from 35.7 ± 0.5 and 37.4 ± 0.5 MPa). The final phase compositions after hydration of the mixtures were determined on the base of XRD data, assumed mechanism of hydration and rational chemical analysis. The constitutive phases were tobermorite, portlandite, and amorphous Ca(OH)2, ettringite and amorphous like ettringite phase, gypsum, hydroxyapatite and barite. © 2014 The American Ceramic Society.


Jokanovic V.,Vinča Institute of Nuclear Sciences | Colovic B.,Vinča Institute of Nuclear Sciences | Jovic N.,Vinča Institute of Nuclear Sciences | Babic-Stojic B.,Vinča Institute of Nuclear Sciences | Jokanovic B.,SGL Carbon
International Journal of Applied Ceramic Technology | Year: 2013

Low-temperature synthesis of fluorapatite/fluorohydroxyapatite with precursor mixture previously mechanochemically treated is described in this article. Ethylene vinylacetate/versatate copolymer as a surface active substance was mechanically treated to obtain a core-shell system with strongly controlled grain size. Despite usual behavior of mechanically activated systems, only an amorphous phase formed from precursor ions present in the mixture composed of β-Ca2P2O7, CaCO3, CaF 2, and unreacted Ca(OH)2 was obtained during milling for 5 min to 8 h. The mixture contained depots of labile F- ions conserved in micelles cages, which are useful for teeth protection from carries. For transformation of these amorphous phases into fluorapatite, an additional low thermal treatment was necessary. The mechanism of the precursor mixture transformation into fluorapatite during milling and thermal treatment was investigated using FTIR spectroscopy and X-ray diffraction. The morphology and size distribution of the obtained powders was studied using SEM and TEM. © 2013 The American Ceramic Society.


Colovic B.,Vinča Institute of Nuclear Sciences | Jokanovic V.,Vinča Institute of Nuclear Sciences | Jokanovic B.,SGL Carbon | Jovic N.,Vinča Institute of Nuclear Sciences
Ceramics International | Year: 2014

The biomimetic deposition of hydroxyapatite (HA) on the surface of SiO 2 thin film coated metal substrates was developed and investigated. The structural investigations of HA were made by XRD and FTIR-ATR, while morphological and chemical changes during HA biomimetic deposition on the surfaces of silica thin films were investigated by SEM with EDS. The HA film thicknesses were estimated from the mass changes of samples including the corresponding correction of the pore volume inside of them, which was calculated by the Lecloux and Pirard method based on the Dollimore-Heal method. © 2013 Elsevier Ltd and Techna Group S.r.l.All rights reserved.

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