Rapid urbanisation and a growing population have exacerbated noise pollution worldwide, highlighting the need for advanced sound absorption technologies. Conventional sound absorbers, including porous and resonant materials, are widely used for noise control but often face limitations in low-frequency and tuneable absorption. Magnetorheological (MR) materials, whose mechanical properties can be altered by external magnetic fields, offer potential for adaptive sound absorption. This review provides an overview of sound absorption fundamentals and conventional absorbers before examining the application of MR foams and MR elastomers as sound absorbers. The fabrication approaches, structural characteristics, and sound absorption performance of MR-based absorbers are discussed, with attention to key parameters affecting acoustic performance, including magnetic particle content, magnetic field strength, and material structure. Existing studies generally indicate that increasing magnetic particle content can enhance low-frequency absorption, while varying the applied magnetic field strength enables tuning of the frequency corresponding to the maximum sound absorption. The current challenges and prospects of MR sound absorbers are also discussed, highlighting the need for further research into material optimisation, standardised testing protocols, and scalability.
Cardiovascular diseases responsible for approximately 19.8 million deaths annually, necessitate advanced cardiac repair materials that exhibit mechanical compliance, electrical functionality, and stability under dynamic deformation to match the native myocardium. This study reports the fabrication and characterization of CNT-reinforced re-entrant lattice cardiac patches using a flexible photocurable resin and DLP-based additive manufacturing by carbon nanotubes (CNTs) to realize the mechanical flexibility and inherent strain-sensing behavior. Re-entrant lattice geometries were designed based on auxetic principles to promote lateral expansion and strain redistribution under tensile deformation. The mechanical test demonstrated that pure resin patches have a higher tensile strength (0.33–0.35 MPa), but limited extensibility, whereas CNT-reinforced patches have a low stiffness (0.015–0.05 MPa), but a high elastic deformation and energy dissipation. SEM, XRD, and FTIR analyses established the CNT dispersion was homogeneous, crystalline of the graphitic was preserved, and the interfacial between the polymer and CNT were strong. The CNT-reinforced patches exhibited stable piezoresistive behavior under both static and cyclic tensile deformation. Geometry-dependent electromechanical sensitivity was observed, with gauge factors ranging from 2.9 to 5.3. Cyclic loading tests showed repeatable resistance responses with over 95
This study presents a thermal stress FEM model of five different Traveling Wave Tube Amplifier components subjected to a 300K–823K continuous heating/cooling cycle. The effects of variation in the constitutive composite brazed material properties, complex shape structure, and artificially introduced microstructure parameters (pore shape, size, and location) are analyzed. Von Misses Stress is used as a decisive parameter. Complexity in shape, pore location, and porosity are shown to affect thermal endurance. Microstructures with sharp edges concentrate more stress than spherical or edgeless microstructures and thus lower thermal performance. The presence of microstructures near the interface edge (near-ceramic) induces greater thermal stress than near the filler location. The results depict that an optimal porosity value exists, which minimizes thermal stress. An empirical linear relation indicates that the braze material property and shape factor are the dominant parameters. This study can be useful to the aerospace industry for the virtual prototyping of TWTA.
Iron- and silver-co-doped TiO₂ nanorods (DTNs) were synthesized through a sol–gel-assisted hydrothermal route to investigate the influence of calcination temperature on their nanostructural evolution, optical properties, and photocatalytic performance toward methylene blue degradation. The uncalcined sample exhibited the smallest crystallite size, the highest estimated surface area, the lowest optical bandgap, and the highest Urbach energy, indicating the presence of abundant defect-related electronic states that promoted visible-light absorption and charge transfer. Increasing the calcination temperature progressively reduced lattice defects and estimated surface area while increasing crystallite size and bandgap energy, resulting in lower photocatalytic activity. Among all samples, the uncalcined DTNs achieved the highest degradation efficiency (75.84
Lignocellulosic biocomposites offer a renewable alternative to petroleum-derived materials, yet their photodegradation behavior under accelerated weathering remains insufficiently characterized from a reliability standpoint. This study evaluated the mechanical performance and degradation patterns of a laminar biotextile–biogrid biocomposite intended as a biodegradable geosynthetic analogue for short- to medium-term erosion-control and soil-protection applications. The material was assembled from a Typha domingensis core (leaf blades and basal sheath fibers, forming the fibrous biotextile) and a Boehmeria nivea (ramie) structural biogrid, both impregnated with castor oil-based polyurethane resin. Specimens were subjected to accelerated UV aging (water immersion, thermal cycling at 105 °C, and UV exposure per cycle) for 120 cycles, totaling 720 h of exposure ( 570 h effective UV radiation). Tensile and puncture properties were quantified under uniaxial and multiaxial loading, and temporal trends were assessed through Generalized Linear Models, Generalized Estimating Equations, and Weibull reliability functions. Tensile strength remained stable throughout the aging program, maintaining a mean of 2.92 kN·m–1, while strain capacity declined by 8.11
Silver-substituted cobalt ferrite nanoparticles (Co1−xAgxFe2O4; x = 0.0, 0.2, 0.4, and 0.6) were synthesized by the sol–gel auto-combustion method to investigate how Ag solubility limits and phase segregation govern the structural, morphological, and magnetic evolution of cobalt ferrite. While prior literature has extensively focused on narrow, low-doping concentrations where single-phase structures are preserved, the behavior of this system at higher substitution levels and the influence of phase segregation on the coupled structural and magnetic evolution remain insufficiently understood. This work addresses this knowledge gap by systematically investigating the Ag solubility limit and its influence on phase segregation and magnetic evolution. X-ray diffraction revealed the appearance of metallic Ag secondary phases from x = 0.2, indicating that the Ag solubility limit is reached at or below this composition. Consequently, compositions with x > 0.2 behave as Ag/CoFe₂O₄ nanocomposites rather than true substitutional ferrites, resulting in a non-linear variation of the lattice parameter (8.37–8.43 Å). The crystallite size decreased to 19.60 ± 1.56 nm at x = 0.4 because of Zener pinning, accompanied by the maximum microstrain (18.20 × 10⁻3) and dislocation density (26.03 × 1014 m⁻2). The evolution of lattice strain and phase segregation fundamentally altered the magnetic behavior, suppressing the saturation magnetization from 19.54 emu/g for pristine CoFe2O4 to 0.13 emu/g at x = 0.2, followed by 0.35 emu/g at x = 0.4 and a partial recovery to 11.60 emu/g at x = 0.6 as the ferrite phase became stabilized. This study demonstrates that the magnetic response is governed by the interplay between Ag solubility, phase segregation, lattice strain, and ferrite phase stabilization rather than by Ag concentration alone. These findings establish the critical role of Ag solubility limits and phase segregation in governing the structural and magnetic evolution of cobalt ferrite nanoparticles, providing fundamental design principles for ferrite-based magnetic materials and magnetically recoverable functional systems.
The unsteady heat and mass transport properties of a Casson hybrid nanofluid comprising plasma-activated water (PAW) with molybdenum disulphide (MoS _2 ) nanosheets and MXene (Ti _3 C _2 T _x ) along a porous vertical cone under non-isothermal boundary conditions are examined. The Effects of magneto hydrodynamics (MHD), thermal radiation, viscous dissipation, internal heat source/sink, chemical reaction, activation energy and Soret-Dufour cross-diffusion are taken into consideration. Plasma activation supplies the base fluid with reactive oxygen and nitrogen species, which alter the thermophysical characteristics of the base fluid and improve its convective transport. The nonlinear partial differential governing equations for momentum, energy and species concentration are put into dimensionless form and solved numerically using an implicit finite difference methodology based on Crank–Nicolson method with homas algorithm. Furthermore, an artificial neural network (ANN) model is used to check the numerical findings and to estimate their prediction performance. A comprehensive parametric research is performed to evaluate the effects of the main dimensionless factors on the velocity, temperature and concentration fields as well as on the skin-friction coefficient, Nusselt number and Sherwood number. The findings demonstrate that the PAW based MoS 2–MXene hybrid nanofluids may significantly increase the heat and mass transfer performance, especially with the synergistic impact of activation energy and cross-diffusion processes. These results indicate the promise of the PAW-based hybrid nanofluids for enhanced thermal and mass transfer applications.
Steam turbines remain central to large-scale electricity generation globally, with continued improvements in efficiency relying heavily on advances in high-temperature materials and their qualification for increasingly demanding operating conditions. This review examines the evolution of steam turbine materials from conventional Cr–Mo–V steels to advanced ferritic–martensitic steels and Ni-based superalloys developed for ultra-supercritical (USC) and advanced ultra-supercritical (A-USC) applications (700–725 °C, 30–31 MPa). Emphasis is placed on the microstructure–property relationships governing creep strength, fatigue resistance, oxidation behaviour, and long-term degradation. Emerging material characterization techniques, including advanced microscopy, diffraction-based methods, and data-driven approaches, are critically assessed for their role in understanding degradation and supporting material qualification. Environmental degradation mechanisms, rotor-scale testing methodologies, additive manufacturing and challenges associated with large-component manufacturing and life prediction are also reviewed. By synthesizing mechanistic understanding with plant-level efficiency requirements, this review outlines critical knowledge gaps and proposes future directions in alloy design, failure redressal, surface engineering, and materials development for high steam temperatures (> 600 °C). Finally, sustainability benefits arising from higher plant efficiency (> 45
Zinc aluminate (ZnAl₂O₄) nanoparticles have attracted sustained attention due to their outstanding thermal stability, chemical robustness, and versatile optical properties. This review article is intended to present a thorough analysis of the synthetic methods of ZnAl₂O₄ nanomaterials, their synthesis–structure–performance relationship and application-oriented comparison. A systematic and comparative analysis of conventional synthesis techniques—such as sol–gel, co-precipitation, hydrothermal, and microwave-assisted routes—alongside emerging green synthesis and other strategies has been discussed, with explicit emphasis on how processing parameters govern particle morphology, defect chemistry, crystallinity, and functional efficiency. The novelty of this work lies in consolidating dispersed literature data into a unified framework that directly links synthesis conditions to performance metrics relevant to specific technological applications. Key findings demonstrate that rational control of synthesis pathways can substantially enhance photocatalytic activity, catalytic efficiency, and optical response. The review further highlights the practical relevance of ZnAl₂O₄ nanostructures in photocatalysis, heterogeneous catalysis, optoelectronic devices, advanced ceramics, and environmental remediation, offering clear guidelines for designing sustainable and high-performance ZnAl₂O₄ nanomaterials for next-generation technologies.
Bacterial infections pose a severe and growing threat to public health and the global economy, exacerbated by the rise of drug-resistant pathogens. This urgent challenge demands the development of non-antibiotic strategies with robust antibacterial activity. Nanotechnology-driven photothermal therapy (PTT) facilitated by near-infrared (NIR) light has emerged as a promising alternative. However, conventional PTT using 808 nm light (NIR-I window) suffers from limitations such as limited tissue penetration and potential collateral cell damage due to non-specific heating. To overcome these limitations, we have developed bovine serum albumin (BSA)-stabilized Cu₂₋ₓSe nanoparticles (NPs), which exhibit strong NIR-II absorption (1064 nm) enabling deeper tissue penetration and reduced off-target effects. Under 1064 nm irradiation, Cu₂₋ₓSe NPs achieve bactericidal temperatures of 53.6 °C and 57.2 °C at low power densities (0.5 and 1 W cm⁻², respectively), while BSA coating supports colloidal stability and biocompatibility. These NPs demonstrate > 99
Cold Welding (CW) is a solid-state metal joining process associated with the unintended bonding of metal surfaces in space. The bond can be classified as a weld (joint strength = σyield) or partial weld (< σyield). CW is closely related to Cold Pressure Welding (CPW) but occurs in ambient environment, relies on high plastic deformation and multi-upsetting actions to disrupt surface oxides. This action enables virgin metal-to-metal contact for bond formation. This research aims to quantify the determining factors (forces, metal candidates, surface conditions and oxidation factors) and their relative contributions in CPW so it may be adopted for in-situ CW of spacecraft hulls after micrometeoroid/debris perforation. A commercial CPW machine was adapted to investigate the effect of applied forces and number of upsets using Copper C101 rods (Ø 3 mm, N6), a material which is commonly used in electrical cables and gaskets. Two fixed force conditions were tested, F_1 = 2228 N (3.7 × σyieldC101) and F_2 = 1794 N (3 × σyieldC101). No weld was observed with less than three upsets under these loading conditions. Results show that higher force initiates bond formation, but it is weak (47
This study investigated the potential of water hyacinth-derived biocarbon as a single-layer radar absorbing material (RAM) in the X-band frequency range through thickness optimization via a genetic algorithm (GA). The biocarbon was synthesized via carbonization and characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), and electromagnetic measurements via the Nicolson–Ross–Weir (NRW) method. The XRD results indicated that the material was predominantly amorphous, whereas the SEM observations revealed a porous morphology with irregular cavity-like structures formed during carbonization. Electromagnetic characterization revealed relatively stable permittivity behavior with a weak magnetic response, suggesting that dielectric loss is likely the dominant microwave attenuation mechanism. Reflection loss analysis revealed a minimum RL value of approximately − 11.65 dB at 9.7 GHz, with an optimized absorber thickness of approximately 1.53 mm. Compared with the nonoptimized configuration, the optimized structure exhibited improved impedance matching behavior. These findings suggest that water hyacinth biocarbon has potential as a lightweight and environmentally friendly microwave absorbing material. However, further studies involving wider frequency ranges and more complex absorber configurations are still needed to improve the absorption performance.
This study investigates the development and comprehensive characterization of areca fibre–silicon carbide (SiC) reinforced hybrid epoxy composites for lightweight automotive applications. Hybrid composites containing 10–25 wt
The ability to predict concrete compressive strength is important in early-stage mix design screening. Thus, the predictions made from these models must match the actual data that was used to train and validate them. Therefore, this study assesses machine learning models using the publicly available UCI concrete compressive strength data set that has 1030 tabular entries. The tabular entries are defined by the following variables; cement, blast furnace slag, fly ash, water, superplasticiser, coarse aggregate, fine aggregate, curing time and measured compressive strength. As such, the study is framed as a transparent tabular prediction benchmark rather than as an experimental evaluation of microsilica and rubber aggregate based concretes. It does not claim to have evaluated any new test pieces, nor does it make any claims regarding SEM imaging or microstructural measurement of those test pieces. Further, there is no claim related to the use of any durability testing procedures. Several machine learning algorithms including support vector regression (SVR), random forest, XGBoost, artificial neural network (ANN) and an optimised tabular ensemble (TE), were each developed under the same leakage-controlled validation methodology. Performance metrics were provided based on both the native test set(s) and a common subset of the test set(s). Metrics included R2, RMSE, MAE, MAPE along with residual diagnostic and graphical error analyses. The new framework also emphasizes reproducibility, fairness of comparison and transparency of data domain limitations. In addition to supporting computer-based screening of conventional concrete strength databases, its results indicate what will be required for future studies that contain micro silica, rubber aggregates, microstructural measurements and/or durability measurements in their respective databases.
Arterial stenosis can lead to severe cardiovascular disease due to the obstruction of normal blood flow. In this study, a fractional-order mathematical model is formulated to investigate magnetohydrodynamic (MHD) Casson blood flow containing TiO _2 nanoparticles in an inclined stenosed artery using Caputo-Fabrizio derivative (CFD). Flow governing equations for momentum, energy, and concentration are formulated by taking thermal radiation and chemical reactions. Exact analytical solutions of the proposed problem are achieved using Laplace and Hankel transforms (HTs). The impact of main physical parameters such as Hartmann number, fractional order parameter, Casson parameter, thermal radiation parameter, and chemical reaction parameter on the velocity, temperature, and concentration fields is analyzed through graphical and tabular representations. The obtained result shows that the fractional order parameter offers an enhanced fluid flow. With a stronger magnetic field, the velocity distribution is high in the flow, whereas higher values of thermal radiation raises the temperature distribution. In contrast, an enhancement in the amount of chemical reaction parameter reduces the concentration distribution. An artificial neural network (ANN) using the Levenberg-Marquardt (LM) backpropagation algorithm with a 70
Ceramic materials play a vital role in advanced electronic, optical, and energy applications due to their unique structural and functional properties. This review focuses on the mechanochemical synthesis (MCS) of complex ceramic oxides such as BaTa₂O₆, MgTa₂O₆, and BaTiO₃, highlighting their advantages over conventional high-temperature synthesis methods. Mechanochemical synthesis, particularly through high-energy ball milling, enables the formation of phase-pure, nanostructured ceramics with improved dielectric, piezoelectric, and ferroelectric properties at significantly lower synthesis temperatures. The impact of milling time, annealing conditions, and precursor selection on the microstructure and properties of these ceramics is extensively discussed. Additionally, alternative synthesis routes, including co-precipitation, sol–gel, oxalate decomposition, and hydrothermal methods, are compared with mechanochemical techniques in terms of process simplicity, material homogeneity, and scalability. The effects of doping and compositional tailoring on dielectric behaviour, the role of real-time monitoring techniques in understanding mechanistic pathways, and the application potential of these ceramics in sensors, capacitors, actuators, and energy storage systems are also explored. Emphasis is placed on the sustainability of mechanochemical synthesis as a green synthesis approach and its capacity to produce defect-engineered, high-density materials with superior performance. This review underscores mechanochemistry as a cornerstone in modern ceramic synthesis, offering versatile, cost-effective, and scalable solutions for next-generation functional materials.
Retrofitting of reinforced concrete (RC) beams with FRP materials addresses issues of structural deterioration, offering a robust alternative to traditional steel reinforcement. This study experimentally investigates the flexural strengthening of RC beams using near-surface mounted (NSM) carbon fiber–reinforced polymer (CFRP) laminates placed in vertical (90°) and inclined (60°) orientations. Six beams, four strengthened and two control beams made up that were tested. The results revealed that NSM CFRP greatly improved ductility, flexural capacity, and delayed failure. The average ultimate load improved by almost 63
Spur gears are particularly vulnerable to vibration-induced resonance, noise production, dynamic stress concentration, and early fatigue failure while running at high speeds and under cyclic loading circumstances. The dynamic performance of conventional steel gears in sophisticated transmission systems is limited by their weak intrinsic damping capability, despite their high strength and wear resistance. This work uses advanced finite element modal and harmonic response analysis to examine the dynamic behavior and vibration attenuation properties of hybrid carbon-fiber-reinforced metal matrix composite (MMC) spur gears. Six material configurations were compared, including carbon-fiber/epoxy composite, stainless-steel-reinforced hybrids (CF/Epoxy/SS316 and CF/Epoxy/SS304), aluminum-reinforced hybrids (CF/Epoxy/Al6082 and CF/Epoxy/Al1050), and SCM420H steel. Equivalent orthotropic elastic formulations obtained using rule-of-mixtures homogenization were used to represent the composite materials. Mesh-independent models with realistic elastic support and frictional contact boundary conditions were used in ANSYS Workbench 2023 R1 for finite element simulations. The Block Lanczos solver was used for modal analysis in order to obtain natural frequencies and mode shapes. Harmonic response analysis was then used to assess resonance characteristics. Rayleigh damping implementation and characterization based on Dynamic Mechanical Analysis (DMA) were used to incorporate damping features. The findings show that, in comparison to traditional steel gears, all hybrid composites have noticeably higher natural frequencies and better damping characteristics. Because of its greater specific stiffness, Composite A (80
Zinc oxide nanoparticles (ZnO NPs) were synthesized via a co-precipitation method and doped with Eu3+ ions using three different approaches: in-situ doping during synthesis (Eu:ZnO(P)), post-synthesis doping (Eu:ZnO(S)), and modification of commercially available ZnO (Eu:ZnO(C)). Structural analysis by X-ray diffraction (XRD) confirmed the preservation of the hexagonal wurtzite phase in all samples, while peak shifts and broadening indicated lattice distortion associated with Eu3+ incorporation. The crystallite size decreased from 24 to 16 nm for Eu:ZnO(S) and from 61 to 36 nm for Eu:ZnO(C), demonstrating the influence of the doping route on crystal growth. Optical characterization using UV–Vis spectroscopy demonstrated band-gap narrowing from 3.05 to 2.95 eV for Eu:ZnO(C), from 3.00 to 2.90 eV for Eu:ZnO(S), and to 2.85 eV for Eu:ZnO(P). Photoluminescence (PL) analysis revealed enhanced emission intensity and a redshift in doped samples, attributed to defect-related states associated with Eu incorporation. Among all samples, Eu:ZnO(S) exhibited the highest PL intensity and a pronounced emission band near 592 nm, highlighting the effectiveness of post-synthesis doping. These findings demonstrate that the doping strategy and nanoparticle origin play a crucial role in tailoring the structural and optical properties of ZnO nanomaterials for potential optoelectronic and photonic applications.
In this study, WS₂/ZrB₂ hybrid nanoparticles were successfully incorporated into AZ31 magnesium alloy to simultaneously improve strength and maintain ductility. The ZrB₂ micropowder was milled to produce nanopowder, then mixed with WS₂ nanoparticles through additional milling to form a hybrid reinforcement. The hybrid nanoparticles were introduced into the molten AZ31 matrix via stir casting, and nanocomposites with various reinforcement contents were fabricated. Optical microscopy (OM) and scanning electron microscopy (SEM) revealed a relatively uniform distribution of the reinforcing particles, significant grain refinement, with the average grain size decreasing from 46 µm in the unreinforced alloy to 31 µm in the nanocomposites, and notable modification of the Mg₁₇Al₁₂ intermetallic phase morphology. EDS and XRD analyses confirmed the presence of the hybrid reinforcements and the identified phases. Mechanical testing showed that the AZ31/1 vol.
