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
EUGENIA TANASĂ
Abstract
One extremely promising method for producing hydrogen sustainably and storing energy is the photoelectrochemical (PEC) splitting of water with solar energy. Hematite is a good photoanode material for water splitting because of its advantageous qualities, according to recent study in this area: it is an n-type semiconductor, possesses a band gap appropriate for visible light absorption, exhibits high chemical stability, and is abundantly available on Earth. This review presents various strategies for modifying hematite to enhance its performance. These modifications include element doping, nanostructure design and fabrication, co-catalyst integration, heterostructure formation and the interdependence between the structure and performance of hematite.
Keywords
solar energy, hematite, photoanoes
XIANWU JING, XIAOJIN ZHOU, TENG GONG, TAO WANG, YANG WANG, GUOQING LIU, KAIJUN WANG
Abstract
This research employed molecular dynamics simulations to explore the distribution of sodium dodecyl sulfate (SDS) at the n-hexane/water interface. Once the SDS concentration surpasses the critical micelle concentration(cmc), a large portion of SDS migrates to the n-hexane/water interface, establishing a thin layer where sulfonic acid groups are oriented towards the water phase and carbon-hydrogen chains are directed towards n-hexane, a small amount of SDS forms spherical micelle with sulfonic acid groups facing the water phase, while carbon-hydrogen chains aggregate in the interior of these spherical structures. The sulfonic acid group of SDS forms multiple h-bonds with water, shows strong interaction energy; while the carbon hydrogen chain itself has only weak van der Waals interactions with surrounding molecules. The thickness of SDS- layer at the n-hexane/water interface is about 2.06 nm, with a maximum number density of about 0.25 per nm3, and average area occupied by a single SDS- is about 0.21 nm2. According to radial distribution function (RDF) result, due to the attractive effect of positive and negative charges, the first coordination layer of Na+ ions and oxygen atoms on sulfonic acid groups is about 0.21 nm. This study investigated the distribution of SDS at n-hexane/water interface, vividly demonstrating the mechanism by which SDS reduces the interfacial tension between oil and water, and providing guidance for oilfield development.
Keywords
N-hexane/water interface; Molecular dynamic simulation; Sodium dodecyl sulfate; Weak interaction analysis
S. DHANALAKSHMI, T. JESUDAS, M. PRADEEP KUMAR
Abstract
The objective of this research study is focused to improve the wear resistance of the reinforced Al6063 hybrid metal matrix composite. The secondary particles like Al2O3 /TiO2are used as a reinforcement particle and the samples fabricated using stir casting technique with the base material Al6063 alloy. The fabricated samples were analyzed using Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscope (SEM) for understanding the potential of fabricated samples. Dry sliding wear test was conducted for the composite samples. The major wear process parameters such as load, sliding distance were considered for analysis work. The reinforcement particles such as Al2O3 /TiO2 also were considered as one of process parameter for wear analysis. The results of Variance of analysis clearly statethat reinforced secondary particles were the most influencing wear process parameter. The validation of desirability function analysis results reveals that the obtained optimal solutions were effectively enhance the wear resistance property for fabricated hybrid metal matrix composite (Al6063/Al2O3 /TiO2).
Keywords
Al 6063, Al2O3 /TiO2, DFA, Wear, RSM.
CHIENTA CHEN, SHINGWEN TSAI
Abstract
The rapid increase in terrain variability, climatic factors, axle load, and traffic volume has significantly affected the performance of asphalt pavements on expressways, particularly in harsh environmental conditions. In some cases, the service life of expressway pavements is far shorter than the expected design time. Certain sections of expressways face pavement failures just one or two years after opening, including cracks, potholes, rutting, and oil flooding. These problems not only disrupt the normal flow of traffic but also substantially increase maintenance and repair costs. This study focuses on diagnosing and addressing the causes of asphalt pavement failures, specifically in Jiangsu Province, China, where various asphalt pavement diseases were reported in 2020. By calculating the porosity of asphalt mixtures, we assess the water permeability, strength, and durability of the materials. Applying Mohr-Coulomb theory, we evaluate the high-temperature shear strength of asphalt mixtures and analyze rutting depth. Our findings indicate that rutting is the primary distress type on expressways in Jiangsu, with a rut depth of [3-8] mm observed in 67% of the total road network. Additionally, the pavement smoothness of expressways remains within a range of 0.5-1m/km for 85% of the highway network. We also analyze lateral and longitudinal fractures, which constitute 97% of repairs, with transverse cracks becoming prevalent after 6 years of service under high axle loads. This suggests the need for early preventive measures within the first 6 years of service to mitigate the development of cracks.
Keywords
asphalt pavement, highway, pavement diagnosis, repair technology, environmental impact, rutting, crack formation, traffic load.
MĂDĂLINA-OANA MIHĂILĂ, DENISA FICAI, OANA DAMIAN, BOGDAN ȘTEFAN VASILE, ALEXANDRA CRISTINA BURDUȘEL, ANDREI PĂDURARU, ECATERINA ANDRONESCU
Abstract
Before discussing innovative materials and nanomaterials for the conservation and restoration of the national archaeological heritage, it is necessary to dentification and characterization of the main raw materials (plastic and non-plastic materials) and auxiliary materials used to obtain the ceramic body (part I) and the decoration on the surface of the sherd: sculptural – simultaneous with shaping and pictorial, monochrome or polychrome, existing on the inner or outer surface of the ceramic pieces. Thus, according to their origin and the way of formation, by sedimentation, thermal processing – sintering and vitrification, which determines the composition, properties, color and degree of refractivity, they are classified into common clays and superior clays, differentiated by the plasticity index, vitrification being influenced by the ratios of the component oxides, by the firing temperatures: low, medium or high and by the types of atmosphere inside the kilns: oxidizing in the case of white, gray and red ceramics or reducing in the case of black ceramics, partial or complete, made in a single phase or two stages.
Keywords
plastic clay, sculptural decoration, polychrome decoration, ceramic engobes, ceramic glazes, the color, coloring oxides, alkaline oxides and alkaline earth oxides.
SALEM MERABTI, LAYACHI GUELMINE, MEZIANE KACI
Abstract
This study investigates the seismic performance of reinforced concrete buildings ranging from 5 to 20 stories using nonlinear static pushover analysis. Four shear wall bracing configurations are considered: L-shaped peripheral walls, central core, double central core, and double peripheral core systems, with wall thicknesses of 15, 20, and 25 cm, all subjected to unidirectional lateral loading. Although these configurations are widely implemented in both moderate and high seismicity regions, few comparative studies have assessed their nonlinear seismic resistance. The results indicate that central core configurations provide superior control of inter-storey drift, with a significant reduction in lateral displacements—up to 48% compared to peripheral wall systems. In contrast, peripheral wall systems exhibit higher drift demands, reaching a maximum of 0.124% for 15 cm thick walls. The analysis also highlights the effectiveness of L-shaped walls in mid-rise buildings, particularly those with wall thicknesses of 20 and 25 cm. The study of deformation mechanisms reveals a concentration of plastic hinges and thus stress in L-shaped wall systems and at beam-wall joint regions.
Keywords
Multi-storey building, Nonlinear pushover analysis, Reinforced concrete shear wall, Inter-storey drift, Shear stress, Overturning moment.
ALI SABERI VARZANEH, MAHMOOD NADERI
Abstract
In concrete design, durability is as vital as strength, especially in aging structures exposed to harsh environmental conditions. Increased permeability over time compromises structural integrity. Polypropylene (PP) fibers help limit cracking, which in turn reduces permeability. Traditionally, assessing permeability requires destructive core sampling. This study introduces a novel approach—the “cylindrical chamber” test—to evaluate permeability directly on structures. Validation of this method confirmed its reliability. Results indicated that incorporating PP fibers reduced permeability in C25, C35, and C45 concretes by 22.5%, 20.2%, and 16.3%, respectively. XRD analysis revealed that PP fibers influenced Ca(OH)₂ crystallization and enhanced C-S-H formation. MIP results showed a 24.5% increase in pore volume and 32.8% rise in pore surface area in C45 concrete with fibers, yet overall permeability declined. This confirms the effectiveness of PP fibers in improving durability without the need for invasive testing.
Keywords
Concrete, durability, Fiber, Strength, Novel method.
KARTHIKEYAN R, PARTHEEBAN P, THOLKAPIYAN.M, SIVAKUMAR, SUGUNA K, GAAYATHRI KK
Abstract
This work discusses the outcome of Finite Element Analysis using ANSYS Workbench, to analyse the cyclic behavior of rubberized concrete beams with steel fiber reinforcement. The investigation focuses on substituting coarse aggregate with sand coated rubber shreds, obtained from waste conveyor belt, with the sand coating applied using resin. The study examines rubber shreds in proportion of 2.5%, 5% and 7.5%, combined with steel fibres at volume fraction of 0.5% and 1%, total of seven beams were cast and tested under cyclic loading in a standard loading frame of 500kN capacity. The FEA outcomes revealed that reinforced concrete beams with steel fibres and sand coated rubber shreds reveal boosted cyclic efficiency regarding number of cycle’s sustained, maximum deflection and total energy absorption capacity. Load – deflection curves were plotted to compare experimental and FEA for all seven beams. These results have proved very helpful for better understanding the rubberized concrete with fiber reinforcement under cyclic loading, for its use in structural applications.
Keywords
Sand Coated Rubber Shreds, Ultimate Deflection, Steel fiber, Energy Absorption , and Load-Deflection Curve.