Papers by Author: Ioana Demetrescu

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Authors: M.M. Sovar, E. Aldea, V. Mitran, Florin Miculescu, Ioana Demetrescu
Abstract: This paper it supposed to demonstrate how to obtain the hydroxylapatite on the surface of TiAlNb biomaterial used as dental implant. The bone-forming bioactivity of TiAlNb is associated with its chemical and structural properties, including composition, porosity, specific surface area and particle size. After different bioactivation surface treatments as chemical and electrochemical treatments, it was observed a better stability for the TiAlNb alloy that was treated electrochemically.
Authors: Doru Vornicescu, Katerina Solanska, Ioana Demetrescu, Matthias Frentzen, Michael Keusgen
Abstract: : The pellicle on oral surfaces represents a central interface for the formation of biofilms. Among other things it causes the first adsorption of bacteria. The dynamics of pellicle formation, on tooth surfaces and the influence of oral therapeutics on the pellicle structure are fairly unknown. With the method of surface plasmon resonance (SPR), the formation of salivary pellicle structures on hydroxylapatite (HAP) surfaces covering a very thin (~50nm) layer gold on a glass prism was recorded in real time without labeling or destruction. As pellicle forming substrates natural pooled human saliva (NS) and artificial saliva (AS) were used. To simulate the influence of therapeutic additives on the dynamic of the pellicle forming process, a chlorhexidine preparate (Chlorhexamed Fluid® CHX) on two different concentrations was selected. The binding behavior of a NS and a preparation in terms of an AS were compared. The layer was largely stable against rinsing with buffer. The application of CHX preparations in two different concentrations as an example of an oral therapeutic additive revealed a complex dynamic of adsorption. CHX did not lead to any visible destruction of the pellicle. The introduced method is an excellent tool to illustrate the dynamic effects of pellicle formation or pellicle reorganization by measuring the increase or decrease of the SPR signal in real time.
Authors: D. Ionita, E. Aldea, G. Stanciu, Ioana Demetrescu
Abstract: The aim of this paper was to find and establish the contact: biomaterial implant (TiAlZr) - coated with biologically active molecules; and the correlation between surface characteristics and their efficiency.
Authors: Ioana Demetrescu, R. Luca, D. Ionita, D. Bojin
Abstract: The aim of this paper is to evaluate using ICP/MS (inductively coupled plasma mass spectrometry method ) the small amount of heavy metal existing in temporary teeth of children from area with high environmental risk regarding heavy metals, and to correlate this amount with the state of degradation of such teeth, taking into account that teeth are biological archive.
Authors: D. Ionita, L. Ciohodaru, Mariana Prodana, Ioana Demetrescu
Abstract: The corrosion behavior of titanium alloys and 316L stainless steel has been evaluated and compared with coated materials. The corrosion current and the corrosion rate were evaluated by electrochemical techniques. The ions release from titanium alloys and 316L stainless steel were analyzed using ICP-MS and the HA coatings were observed using FTIR analysis.
Authors: Diana Portan, D. Ionita, Ioana Demetrescu
Abstract: In this paper the elaboration and characterization of TiO2 nanotubes as a function of anodizing conditions are studied taking into consideration electrolyte composition and voltage. The obtained results show that the nanotubes dimensions and surface features depend on elaboration conditions. The technique of surface characteristics investigation (2D and 3 D images) was atomic force microscopy which permitted roughness and porosity evaluation.
Authors: Cristian Pirvu, Mihaela Mindroiu, Ioana Demetrescu
Abstract: In this paper the elaboration and characterization of polypyrrole coatings on active metallic surfaces were performed. The one-step electropolymerization of pyrrole on zinc-coated steel electrodes was investigated under several techniques (cyclic voltammetry, electrochemical impedance spectroscopy, atomic force microscopy) in aqueous medium. Adherent and homogeneous PPy coatings were obtained using tartrate counter-ions. The obtained results show that the PPy coatings increase the corrosion potential and reduce the corrosion current.
Authors: Cristian Pirvu, Mihaela Mindroiu, Rodica Stancu, D. Bojin, Ioana Demetrescu
Abstract: In this paper both electrochemical and surface analysis technique, were performed in order to elaborate and investigate hybrid polymeric composite materials based on polypyrrole (PPy). SEM micrographs of PPy films obtained on zinc chromate electrode presented a cauliflower-like structure. The anticorrosive properties of composite coatings based on polypyrrole were improved using a pre-treatment with chromium salts on the zinc-coated steel surfaces.
Authors: M.M. Sovar, C. Ducu, D. Iordachescu, Ioana Demetrescu
Abstract: The present work is focused on the stability of bioactivated CoCr alloy in biological environment (buffered saline solution (PBS), lactic acid, citric acid). The chemical and electrochemical deposition was characterized by electrochemical methods (open circuit potential, cyclic voltametry), scanning electronic microscope (SEM), x-ray diffractometer (XRD), inductively coupled plasma/mass spectrometry (ICP/MS) and citotoxicity test. The results prove a good electrochemical stability in all cases.
Authors: Ioana Demetrescu, D. Iordachescu, D. Ionita, Stef Manea
Abstract: The aim of this paper is to correlate surface features of degraded temporary teeth from area with high pollution with the cell adhesion and proliferation. Viability of gingival fibroblast (HGF-1, CRL-2014, American Type Culture Collection) was evaluated with a MTT (3-(4,5-dimetiltiazol-2-il)-2,5-difeniltetrazolium bromide ) test and the values are discussed for the most degraded temporary teeth in correlation with the change in surface morphology and hydrophilic/hydrophobic balance, taking into account that cell adhesion is related to a more hydrophilic character.
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