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Pica A.,Polytechnic University of Bucharest | Ficai D.,Polytechnic University of Bucharest | Ficai A.,Polytechnic University of Bucharest | Guran C.,Polytechnic University of Bucharest | And 2 more authors.
Journal of Optoelectronics and Advanced Materials | Year: 2016

Film-forming materials described in this study may be used for long term antimicrobial protection of wood, concrete, gypsum boards and other building materials. The materials have antibacterial properties due to the presence of AgNPs (silver nanoparticles) in their composition. The material has the ability to form a nanomodified polymer matrix which generates in the styrene acrylic binder, nanostructured configuration. This gives the composite material properties, feature and superior performance impossible to achieve at a micro scale. AFFM (antimicrobial film-forming materials) were analyzed of structure by FT-IR (Fourier transform infrared spectroscopy) and in morphologically by electron microscopy (SEM/EDX). The introduction of (0.1-0.2)wt%. AgNPs in AFFM produces an optimum improvement in the antibacterial resistance. It has been shown that the new material (AFFM) does not deteriorate even if subjected to an accelerated aging process. Materials were applied inside a medical unit and found that after 6 months after the application, morphology, structure and biological properties haven't undergone significant changes. Energy dispersive X-ray analysis (EDX) confirmed that AgNPs are well anchored in film-forming material, even after 6 months. Source

Pica A.,Polytechnic University of Bucharest | Pica M.,Carol Davila University of Medicine and Pharmacy | Ficai D.,Polytechnic University of Bucharest | Ficai A.,Polytechnic University of Bucharest | Florica D.,Research Institute for Advanced Coatings
Current Nanoscience | Year: 2015

In crowded public areas (hospitals, airports, railway stations, universities, schools, etc.), surfaces of the materials are exposed to microorganisms. These microorganisms can live both in planktonic and biofilm (colonies of microorganisms) being responsible for the transmission of different infections from human to human. Because of that, the antimicrobial effect is an additional function of film-forming materials. The innovation of these types of materials consists both in choosing and stabilizing the active substance in the polymeric material and in the microbial control. Usage of the AgNPs as active substance induces morphological changes in the structure of the film-forming material, a chemical resistance and an antimicrobial efficacy for a long time. The antimicrobial properties of the new materials reduce the consumption of disinfectants and the number of washing cycles which implicitly leads to reduced maintenance costs. The influence of the AgNPs on the morphology, structure and properties of the material coatings was investigated by EDX, SEM and SPM. The antifungal activity of the film-forming materials was investigated onto 12 cultures of mushrooms. Silver nanoparticles can prevent the formation of biofilms through the killing of the fungus and of the bacteria (both gram-positive and gram-negative) that are present on the surface of materials. Materials coatings were applied in a medical unit and after 12 months from application, it was found that neither morphology or structure nor the antifungal or the antibacterial properties have undergone significant changes. Based on these results it is considered that the film-forming materials based on silver nanoparticles could be used to inhibit the development of micro-organisms on concrete surfaces or plasterboard inside the medical units for long time. © 2015 Bentham Science Publishers. Source

Ababei G.,National Institute of Research and Development for Technical Physics | David V.,Technical University Gheorghe Asachi | Dafinescu V.,Technical University Gheorghe Asachi | Nica I.,Technical University Gheorghe Asachi | And 2 more authors.
IEEE Transactions on Magnetics | Year: 2012

The selective microwave absorption properties of individual and multiple CoFe-glass coated amorphous microwires (GCAW) with small negative value of magnetostriction (λ∼-1× 10 -7, positioned in various configurations are investigated. The deep minimum in the transmission spectra correspond to the first antenna resonance for each length of the individual microwire indicating a selective stop filter behavior. A new type of shielding material in the shape of a multilayered material based on CoFe-GCAW with desired shielding effectiveness and selective absorption of the microwave frequency range by controlling the number of the layers and the length of microwires is proposed and the omni-directional selective shielding properties in the microwave frequency range are determinated. The shielding effectiveness measurements results were SE=4\ dB to 9.5 dB for the samples with two layers, SE=18\ dB to 33 dB for sample with 14 layers, and SE=36\ dB to 48 dB for sample with 28 layers, respectively. © 1965-2012 IEEE. Source

Vaja F.,Research Institute for Advanced Coatings | Guran C.,Polytechnic University of Bucharest | Ficai D.,Polytechnic University of Bucharest | Ficai A.,Polytechnic University of Bucharest | Oprea O.,Polytechnic University of Bucharest
UPB Scientific Bulletin, Series B: Chemistry and Materials Science | Year: 2014

In vitro cytotoxic studies of nanoparticles use different cell line, incubation time and colorimetric assays. In this paper, we investigated the cytotoxicity of different concentrations of ZnO particles hosted in mesoporous silica in Human epidermoid cancer cells using the Trypan Blue exclusion test. The ZnO nanoparticles were prepared by incorporating different amount of zinc nitrate precursor into the channels of mesoporous silica SBA-15. Using Epics Beckman Coulter flowcytometer and FlowJo software the data were expressed as fractions of cells in the different cell cycle phases. The results show that all compounds have cytotoxic effects. © 2009 Universitatea Politehnica Bucuresti. Source

Pica A.,Polytechnic University of Bucharest | Guran C.,Polytechnic University of Bucharest | Ficai D.,Polytechnic University of Bucharest | Ficai A.,Polytechnic University of Bucharest | Dumitru F.,Research Institute for Advanced Coatings
Journal of Coatings Technology Research | Year: 2015

In this article, we present the synthesis of small silver nanoparticles (AgNPs) with an average size of 1–20(50) nm. Three formulations of AgNPs-based materials have been obtained and characterized by varying the weight ratio of the silver nitrate/acrylic polymer. AgNPs were prepared by simple chemical reduction method. The reduction of AgNO3 was done by sodium borohydride in the presence of acrylic polymer, which acts also as a capping agent of AgNPs, avoiding the use of additional protective agents. The elemental analysis of AgNPs was quantified by X-ray fluorescence. The morphology and size of AgNPs were characterized by SEM and TEM–HRTEM, while the colloidal stability of AgNPs was demonstrated by zeta potential measurements. The influence of acrylic polymer on the stability of AgNPs, the particle sizes, and their antimicrobial efficacy was investigated. The results confirm that the introduction of acrylic polymer during the synthesis, acting as a stabilizing agent, increases the colloidal stability and antimicrobial performances of these formulations. © 2015 American Coatings Association Source

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