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Jokanovic V.,Vinca Institute of Nuclear Sciences | Colovic B.,Vinca Institute of Nuclear Sciences | Jovic N.,Vinca Institute of Nuclear Sciences | Babic-Stojic B.,Vinca 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.,Vinca Institute of Nuclear Sciences | Jokanovic V.,Vinca Institute of Nuclear Sciences | Jokanovic B.,SGL Carbon | Jovic N.,Vinca 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.

Jokanovic V.,Vinca Institute of Nuclear Sciences | Colovic B.,Vinca 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.

News Article
Site: www.materialstoday.com

Avcorp Industries Inc has completed its acquisition of the composite aerostructures division of Carbon Composites Inc, a subsidiary of SGL Carbon. The acquisition, which was first announced in July 2015, will reportedly double Avcorp's revenue and expand its carbon composite manufacturing capabilities. Avcorp will receive approximately US$58 million in cash and payment commitments from SGL, the parent company of Hitco and receive in kind supplies and/or payments totaling up to US$7 million through December 31, 2016. Hitco's production is expected to contribute US$93 million in new revenue for Avcorp on an annual basis, while the Hitco Aerostructures division has been operating at a loss. The division will be renamed Avcorp Composite Fabrication (ACF). This story uses material from Avcorp, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.

Jokanovic V.,Vinca Institute of Nuclear Sciences | Colovic B.,Vinca 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.

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