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
PERFORMANCE OF TITANIUM GYPSUM-REPLACED MAGNESIUM CHLORIDE-MAGNESIUM OXYCHLORIDE COMPOSITE MATERIALS
SHUREN WANG, LINRU ZHAO, JIAN GONG, YAN WANG
Abstract
To realize the resourceful utilization of solid waste and develop novel building materials, an experimental study was conducted using titanium gypsum, magnesium chloride, and magnesium oxide as raw materials to prepare test samples. The samples underwent a series of tests, including unconfined compressive strength testing, water absorption analysis, dynamic non-contact full-field strain measurement, scanning electron microscopy, and X-ray diffraction, to investigate the effects of varying titanium gypsum substitution rates for magnesium chloride on the strength, failure modes, and microstructural properties of the resulting composite materials. Results show that as the substitution rate of titanium gypsum increases, the dry density of the composites initially increases and then decreases, while the water absorption rate continues to rise, with a particularly notable increase observed at substitution rates between 10% and 25%. Both flexural and compressive strengths exhibit an initial increase followed by a decrease, reaching their optimal values at a 5% substitution rate, with a maximum improvement of 17.37% in flexural strength and 18.81% in compressive strength. The increase in titanium gypsum substitution rate alters the phase morphology and internal density of the composites, confirming the feasibility of substituting magnesium chloride with titanium gypsum in magnesium oxychloride cement. This substitution strategy not only promotes the utilization of solid waste but also contributes to cost savings, highlighting its potential for practical applications.
Keywords
magnesium oxychloride cement, titanium gypsum, mechanical properties, microstructural analysis
DAVID RESANO, JOSE BARRANZUELA, FABIOLA UBILLÚS, OSCAR GUILLEN, ANA GALARZA
Abstract
High-altitude human settlements, such as those in the Andes and the Himalayas, experience extreme temperature conditions, yet many houses in the Peruvian Andes lack thermal insulation due to the unavailability of affordable materials. As a result, respiratory diseases linked to low temperatures are widespread during the coldest months of the year. This study presents the development of an innovative thermal insulation panel made from locally sourced sugarcane bagasse fibers, bonded with polyvinyl acetate and fabricated using compression molding. The panel achieved a thermal conductivity of 0.043 W/m·K, which allows compliance with Peruvian thermal transmittance standards when applied in layers of approximately 6 cm thickness. The material exhibited a bulk density ranging from 86.7 to 105.3 kg/m³. Mechanical testing showed a low average tensile strength of 0.0144 kg/cm² and a flexural modulus of 0.116 kg/cm², indicating that the panel is not suitable for structural applications. However, it is effective as a non-structural thermal insulation solution. The proposed panel promotes a circular economy by repurposing agricultural by-product and offers a low-cost, biodegradable alternative to synthetic and mineral fiber insulations, contributing to reduce material costs and environmental impact in buildings.
Keywords
Composite, organic material, sugarcane bagasse fibers, thermal insulation, circular economy
MANI P, ARULARASAN R
Abstract
One of the biggest obstacles to using natural fibers in industrial applications is their poor mechanical qualities. The study aims to use carbon and glass fillers to increase the flexural, impact, and tensile strengths of luffa/epoxy composites. Three fillers proportions (5wt.%, 7.5wt.%, 10wt.%) and one luffa proportion (20wt.%) were taken to fabricate the composites. The ASTM guidelines were followed when conducting the experiments. The fillers enhanced the composites tensile, flexural, and impact strengths. Comparing carbon-filled composites to corresponding glass-filled composites, the former showed superior performance. The 7.5wt.% carbon-filled composite shows the highest tensile and impact strength values, whereas the composite without fillers shows the lowest tensile and impact strength values. For flexural strength, 10wt.% carbon-filled composite shows the highest values, whereas the composite without fillers shows the lowest values.
Keywords
luffa fiber, carbon filler, glass filler, tensile strength, impact strength, flexural strength
J.JEGAN, P.ANITHA, SUNANTHA B., J SUDHAKUMAR, R.LOGARAJA, KONA PRAVALLIKA PHANI DURGA
Abstract
Phase-change materials must now be used during construction to reduce greenhouse gas emissions and boost energy efficiency. Considering concrete makes up the majority of construction materials worldwide, incorporating PCMs into concrete can greatly increase a structures energy efficiency. There has been a growing interest in phase change materials (PCMs) in recent years. By utilizing the appropriate PCM and integration approach, the majority of issues associated with utilizing PCM in concrete may be resolved. In this work, Thermal Storage Light Weight Aggregate (TSLWA) was produced by incorporating pumice stone into Paraffin wax. The concrete cube were cast with different replacement ratios of TSLWA with LWA such as 0%, 25%, 50%, 75%, and 100%. The study revealed that increasing PCM content reduced water absorption, with the control sample absorbing 8.5% water compared to only 1.8% for the 100% PCM sample. Compressive strength decreased with higher PCM percentages, with the 100% PCM sample showing significant reduction, emphasizing the need for a balance between thermal properties and structural integrity. Thermal analysis showed that paraffin wax exhibited thermal transitions around 50°C, demonstrating stable thermal behavior up to 300°C. Microstructural examination revealed altered bonding strength due to paraffin wax-filled aggregates, and leakage tests highlighted the effectiveness of epoxy resin coatings in reducing water seepage. Overall, PCM-impregnated pumice concrete improves moisture resistance and thermal performance, offering a promising solution for sustainable construction, though careful consideration of PCM concentration is needed to maintain mechanical strength.
Keywords
thermal storage aggregate, Pumice stone, immersion method, phase change materials, paraffin wax.
A. THOMAS EUCHARIST, V. REVATHI
Abstract
Concrete is one of the most vital building materials next to the water. Day by day, the demand for concrete is escalating with the rising demand for infrastructural development, and the cement industry is one of the dominant contributors to the production of greenhouse gases. So, efforts are essential to make concrete further eco-friendly by adopting cement-free concrete, which helps overcome global warming. In this study, varying compositions of alumina silica materials made up of ground granulated blast furnace slag (GGBFS) and sugarcane bagasse ash (SBA) were supposed to be utilized in the manufacture of geopolymer mortars, and five different ratios of 100:0, 75:25, 50:50, 25:75, 0:100 were proposed. It might be a better solution for both waste disposal problems and issues related to cement production. Combinations of GGBFS and SBA were made with varying concentrations of alkaline solution starting from 10M, 12M, and 14M. The strength properties of the prepared specimens were assessed by conducting compressive strength test on mortar and concrete specimens at 3 days, 7 says, 28 days. Despite the fact that not all of the combinations of the mixes examined had statistically significant results, the test results do suggest that the GGBFS-SBA blend is viable for use in geopolymer. In a 14M geopolymer concrete mix consisting of 100% GGBS, the highest compressive strength of 61 MPa was achieved.
Keywords
Cement-free concrete, Geo polymer mortar, GGBFS, Bagasse ash, Alkaline solution