Nano Hybrids and Composites Vol. 51

Abstract: Although magnetic nanoparticles have been widely studied, limited research has compared different ferrite types and synthesis routes for use in hyperthermia-based bioactive glass applications. This study aims to synthesize magnetic materials from two types of ferrites: magnesium ferrite (MgFe₂O₄) and zinc ferrite (ZnFe₂O₄). These ferrite nanoparticles were synthesized using two distinct methods; the conventional solid-state reaction and the co-precipitation method in order to identify the optimal synthesis route and the most suitable type of magnetic material for hyperthermia treatment. The data demonstrated that MgFe₂O₄ powder with synthesis by using the solid-state method consistently presented higher value of magnetic properties compared to those synthesized by co-precipitation method under higher calcination temperature. Moreover, ZnFe₂O₄ powder was found to be unsuitable for use as a precursor in hyperthermia treatment because of its structure typically leads to antiferromagnetic or superparamagnetic behavior. The effect of MgFe₂O₄ containing in bioactive glass was investigated. The oxide precursors of bioactive glass were mixed with varying amounts of MgFe₂O₄ and subsequently melted to form glass at 1400 °C. The phase formation presented SiO₂ was the dominant phase and coexisted with Na₂CO₃, MgSiO₃, Fe₃O₄, Na₂Ca (PO₄)₂SiO₄, Ca₂SiO₄, and Na₄Ca₄Si₆O₁₈. However, the MgFe₂O₄ phase was not observed in all of glass-ceramic samples. This may be due to MgFe₂O₄ decomposed during the high-temperature melting process at 1400 °C. Nevertheless, these magnetic bioactive glass ceramic samples exhibited magnetic properties, which were attributed primarily to the presence of Fe₃O₄.

Abstract: This study investigates the green synthesis of silver nanoparticles (AgNPs) using Azadirachta indica extract and their incorporation onto orthodontic brackets, enhanced with different concentrations of Azadirachta indica extract. AgNPs exhibit strong antimicrobial activity, making them promising agents in biomedical applications. The synthesized AgNPs were characterized using UV-Vis spectroscopy, FTIR, XRD, and FESEM. The AgNPs were embedded into orthodontic brackets to assess their antimicrobial properties against Staphylococcus aureus and Escherichia coli. Characterization results confirmed the successful formation of crystalline, spherical AgNPs with sizes ranging from 30–68 nm. Antimicrobial testing revealed clear zones of inhibition around AgNP-coated brackets, demonstrating enhanced antibacterial efficacy. The study supports the potential of eco-friendly synthesized AgNPs for improved oral health in orthodontic treatments.

Abstract: A 3D Carbon-Carbon (Cf/C) composite with fabric reinforcement is of interest in applications where flexural loads are dominant, such as in the wings and control surfaces of aircraft and missile systems. Investigating the mechanical properties of these composites is crucial for understanding their performance, especially for designing and analysing composite structures used in extreme conditions. In this research paper, the compression and shear responses of the 3D PF Cf/C composite samples have been determined at room temperature. The samples were machined in the directions of XY, XZ, and ZX, respectively. Then, the Iosipescu shear test and the short beam shear test were employed to evaluate the shear strength and shear modulus of the composite samples, respectively. The material exhibits a strain to failure of around 0.15% in the X direction with a modulus of 54 GPa. In the Z direction, it deforms more, with a strain to failure of approximately 20% and a modulus of 6.2 GPa.

Abstract: This study focuses on the development of sustainable composite materials for automotivebody panels by utilizing sugarcane bagasse and bamboo fibers reinforced with epoxy resin. Theagricultural by-products were first sun-dried, mechanically processed into fine powder, andchemically treated to improve interfacial bonding before being incorporated into the epoxy matrix.Composite specimens were fabricated through a controlled lay-up process and tested for flexuralstrength and impact resistance in accordance with ASTM standards. Experimental results revealedthat sugarcane bagasse composites exhibited the highest flexural strength of 47 MPa, while bamboocomposites contributed greater ductility and flexibility under load. Notably, a hybrid formulation ofbagasse and bamboo fibers achieved the best balance of properties, recording an impact resistance of187 J/m, which is comparable to commonly used polymers. These findings highlight that naturalfiber-based composites not only offer mechanical performance suitable for exterior automotiveapplications but also provide significant advantages in terms of weight reduction, cost-effectiveness,and environmental sustainability.

Abstract: Synthetic dyes such as methyl orange (MO) are persistent water pollutants that pose serious environmental and health hazards due to their toxicity and resistance to biodegradation. Developing efficient, sustainable, and reusable adsorbents for dye removal remains a major challenge in wastewater treatment. This study presents the design and optimization of chitosan/polyethyleneimine/graphene oxide (CS/PEI/GO) hydrogel nanocomposite beads synthesized through controlled cross-linking with glutaraldehyde (GLA) for enhanced adsorption of MO from aqueous solutions. A Box–Behnken experimental design coupled with response surface methodology (RSM) was employed to evaluate the effects of PEI, GO, and GLA concentrations on adsorption capacity. Statistical analysis confirmed the high significance of the cubic model (F = 38.34, p = 0.0001) with a non-significant lack of fit, validating its strong predictive reliability. PEI concentration had the most pronounced effect, providing protonated amine sites for electrostatic interaction with the anionic dye, while GO increased surface area and provided oxygen-containing groups that enhanced hydrogen bonding and π–π interactions. GLA served as a cross-linker to stabilize the hydrogel structure without deactivating active sites. The optimized composition (2.0% PEI, 900 ppm GO, and 2.5% GLA) achieved a predicted adsorption capacity of 23.16 ± 1.05 mg/g, which closely matched the experimentally obtained value of 23.31 ± 1.19 mg/g, with only 2.2% deviation. These findings confirm that the CS/PEI/GO hydrogel nanocomposite provides a balanced integration of structural stability, functional site availability, and high adsorption efficiency, demonstrating its potential as a scalable, eco-friendly material for advanced dye removal and sustainable wastewater treatment.

Abstract: Black limestones were used as structural and ornamental stones in the facades of the four madrasas at Sultan Hasan mosque. Regrettably, the studied black limestone blocks have significantly suffered from deterioration mechanisms, causing severe damage forms such as discolouration, salt crystallization, cracking, fissuring, flaking, granular disintegration, and microbial growth. Examination and analysis of the studied black limestone were performed using polarizing light microscope, scanning electron microscope equipped with EDS, X-ray diffraction, and fungal investigation. The current research mainly presents an experimental study to evaluate the efficiency of nanocomposites prepared from SRC-220 (fluorinated polyurethane) and TiO₂ NPs in the treatment of the studied black limestone. The prepared TiO₂ nanocomposites were used for the treatment of experimental black limestone samples. The effect of TiO₂ nanoparticle concentration on the properties of the fabricated nanocomposites was comparatively tested. Experimental study was implemented using transmission electron microscope, scanning electron microscope, atomic force microscope, static water contact angle, colourimetric investigation, abrasion resistance, self-cleaning activity, and fungistatic efficiency. The results proved that the addition of TiO₂ nanoparticles into SRC-220 pure polymer produced multifunctional nanocomposites characterized by high transparency, good consolidation effect, superhydrophobicity, self-cleaning, and antifugal efficiency. Moreover, it was demonstrated that the concentration of TiO₂ nanoparticles significantly affects the obtained properties of the prepared nanocomposites.

Abstract: The convergence of escalating energy demand and finite fossil fuel reserves has created an urgent, global imperative for sustainable and renewable energy. Perovskite solar cells (PSCs) have quickly become a leading contender in photovoltaics. Their appeal lies in superior optoelectronic properties, high light absorption capabilities, and cost-effective manufacturing, positioning them as a strong alternative to traditional silicon solar cells. However, significant challenges remain, particularly concerning efficiency, long-term stability, and the reproducibility of device performance. This research addresses these issues by focusing on the crucial role of electron transport materials (ETMs). An Ag/rGO/TiO₂ ternary nanocomposite through a simple hydrothermal method, designed to function as a highly effective electron transport layer (ETL) in planar PSCs. When integrated into a PSC and measured under standard AM 1.5G (100 mW/cm²) conditions, the optimized Ag/rGO/TiO₂ ETL delivered a power conversion efficiency (PCE) of 8.72% ± 0.25% (based on an average of N=5 devices). The champion device showed a short-circuit current density (JSC​) of 14.98 mA/cm², an open-circuit voltage (VOC​) of 0.99 V, and a fill factor (FF) of 58.83%. This performance represents a notable improvement over the reference device using pristine TiO₂, which achieved a PCE of 6.56% ± 0.31% (JSC​ = 13.1 mA/cm², VOC​ = 0.95 V, and FF = 52.7%) under identical conditions. This enhancement confirms that the doped materials significantly improve photovoltaic performance by promoting efficient charge transport and suppressing recombination. This work outlines a straightforward and low-cost approach to creating advanced ETMs, which is a vital step toward the commercialization of next-generation perovskite devices.

Abstract: This study investigates the combined stability and sensitivity study of MHD radiative squeezed hybrid nanofluid flow between two parallel circular porous disks. Although numerous studies have examined magnetohydrodynamic (MHD) flows, thermal radiation effects, squeezed-flow configurations, and nanofluids in porous media, existing literature typically addresses these effects in isolation or in simplified combinations. Most prior works have focused on single-nanoparticle nanofluids, neglecting the enhanced thermo-physical behavior of hybrid nanofluids containing two different nanoparticles. The hybrid nanofluid comprises a base fluid embedded with two distinct nanoparticles, enhancing its thermal and flow properties. Several complex interactions including magnetic fields, thermal radiation, resistance in porous media, and squeezing effects influence the flow and thermal characteristics. A system of nonlinear partial differential equations is constructed and then converted into a dimensionless form through the application of similarity transformations. Subsequently, the dimensionless equations are solved using a power series method, and the resulting solutions are analyzed through the Hermite–Padé approximation scheme. A comparison between the current data and a published result has been made with a good agreement. The effect of flow parameters such as porosity parameter, squeeze number, Prandtl number, Eckert number, and radiation parameter on velocity and temperature fields is illustrated graphically. The skin friction coefficient and local heat transfer rate are also evaluated for the relevant physical parameters. The stability of the local heat transfer rate is examined through a bifurcation curve, which indicates that the lower branch represents a stable and physically realizable solution, while the upper branch corresponds to an unstable state. Sensitivity analysis is performed to measure the influence of key dimensionless parameters such as the squeeze number, porosity parameter, and radiation parameter on the local Nusselt number and the result of our model is significant. This work has potential applications in thermal management systems, energy devices, and advanced cooling technologies.