română R. KARIMIA, I. ABBASPOURA, M. AMIRIB
Abstract
Magnetic Nanofluids, such as water-alumina, water-copper, and water-iron oxide, have been attracted due to their interesting thermo physical properties and their application are important branches of engineering such as heat transfer. Research results in recent years show that the presence of nanoparticles increases heat transfer. In this research, we will produce iron oxide (Fe3O4) nanoparticles, by co-precipitation. Two samples of nanoparticles were synthesized, and the size of the produced nanoparticles was around 30-60 nm. The size of the nanoparticles in the fluid (water) and their distribution have a significant effect on the conductivity coefficient of the porous medium (magnetic Nanofluid). Therefore on the heat transfer factor, we will try to reduce the size of the nanoparticles as much as possible and make the particle size distribution uniform. After synthesis, nanofluid is obtained by combining nanoparticles with a certain mass with water. Arabic gum has been used to prevent nanoparticles from sticking together in nanofluid suspension. Zeta potential was obtained for nanofluid suspensions and it was observed that have good stability. To investigate the effects of adding nanoparticles to water in heat exchangers, we used critical heat flux (CHF) analysis. Using CHF, we can obtain the heat transfer factor, and we showed that by adding synthesized Fe 3 O 4 nanoparticles to the base fluid, the heat transfer is improved.
Keywords
Nanofluids, Heat transfer factor, Iron (II, III) oxide, Heat exchangers
DENISA-NICOLETA MUȘAT, ALEXANDRA-CRISTINA BURDUȘEL, ȘTEFAN GAFTONIANU, ANTON FICAI, OVIDIU OPREA, ROXANA POPESCU, ROXANA TRUȘCĂ, ECATERINA ANDRONESCU
Abstract
This research describes the synthesis and characterization of a nanocomposite material that serves dual purposes: promoting bone healing and providing microbial defense. Therefore, 45S5 bioactive glass was synthesized through sol-gel synthesis with zinc oxide nanoparticles produced via microwave-assisted hydrothermal synthesis. The addition of peppermint and lemon balm essential oils at different concentration levels enhanced the material’s biological functionality. The composites considered were analyzed by thermal analysis (TG–DSC), FTIR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) for evaluation. The analysis confirmed the existence of crystalline phases, along with particle morphologies and the incorporation of functional groups. The bioglass particles measured between 2–4 μm in size, while the ZnO nanoparticles size range was from 200 to 400 nm, with a uniform distribution confirmed by elemental mapping. The biocompatibility assessment utilized an MTT assay with MG-63 osteoblast-like cells. The results showed that ZnO caused dose-dependent cytotoxicity; however, the addition of essential oil reduced this effect, mainly when lemon balm essential oil was used at a 2% concentration, which demonstrated improved biocompatibility across all tested concentrations. The developed composite material exhibits enhanced antimicrobial properties and osteoconductivity, along with reduced cytotoxicity, making it suitable for biomedical applications in bone tissue engineering.
Keywords
bioglass, zinc oxide, composite, essential oils, antimicrobial effect
ANDREEA-CRISTIANA ALEXE, ALEXANDRA-CRISTINA BURDUȘEL, ȘTEFAN GAFTONIANU, OVIDIU OPREA, ROXANA POPESCU, ROXANA TRUȘCĂ, ANTON FICAI, ECATERINA ANDRONESCU
Abstract
Bone tissue regeneration presents a significant challenge due to the complexity of bone structures and the limitations inherent in traditional grafting methods. The aim of the study is to describe the development and analysis of a nanocomposite material that combines cerium-doped hydroxyapatite (Ce-HAp) with bioactive glass (45S5 Bioglass) and natural essential oils (sage and thyme). The hydroxyapatite was produced through microwave-assisted hydrothermal synthesis, the bioglass through sol-gel processing, and essential oils were added to the final obtained material. The composite material underwent XRD, FTIR, SEM, and EDAX analysis, which confirmed its crystalline phases, chemical composition, and morphological features. The MTT assay results showed that MG-63 osteoblast-like cells demonstrated high biocompatibility and no cytotoxicity, while samples containing sage essential oil led to increased cell viability. The thermal analysis showed that the composite materials maintained excellent thermal stability. The nanocomposite material exhibits enhanced bioactivity, antimicrobial properties, and cytocompatibility, making it suitable for medical applications. The multifunctional system provides a substitute for standard grafts, while additional biomedical applications can be achieved by adding biologically active ions such as Ag, Sr, Ce, or Zn.
Keywords
hidroxiapatită, oxid de ceriu, uleiuri esențiale, biosticlă, biocompatibilitate