Abstract: Polymeric nanofibers have emerged as a captivating medium for crafting structures with biomedical applications. Spinning methods have garnered substantial attention in the context of medical applications and neural tissue engineering, ultimately leading to the production of polymer fibers. In comparison with polymer microfibers, polymer nanofibers boasting nanometer-scale diameters offer significantly larger surface areas, facilitating enhanced surface functionalization. Consequently, polymer nanofiber mats are presently undergoing rigorous evaluation for a myriad of applications, including filters, scaffolds for tissue engineering, protective equipment, reinforcement in composite materials, and sensors. This review offers an exhaustive overview of the latest advancements in polymer nanofiber processing and characterization. Additionally, it engages in a discourse regarding research challenges, forthcoming developments in polymer nanofiber production, and diverse polymer types and its applications. Electrospinning has been used to convert a broad range of polymers into nanoparticle nanofibers, and it may be the only approach with significant potential for industrial manufacturing. The basics of these spinning techniques, highlighting the biomedical uses as well as nanostructured fibers for drug delivery, disease modeling, regenerative medicine, tissue engineering, and bio-sensing have been explored.

Abstract: Stir-casting with ultrasonic cavitation produced nano-Al2O3-filled AA7150 matrix composites in this study. The SEM microstructure study shows that all composites include nano-Al2O3 particles with consistent particle sizes and homogenous distribution. EDS and XRD showed no secondary phases or impurities in the composite. Optical microscopy showed intense ultrasonic cavitation effects, and nano-Al2O3 particles caused grain refinement in the AA7150 matrix. The composite’s mechanical characteristics improved when the Al2O3 nanoparticle weight percentage (wt.%) increased. With only 2.0 wt.% nano-Al2O3 particles, the composites yielded 232 MPa, 97.52% higher than the sonicated AA7150 matrix alloy. Multiple models were used to characterize the strength of the AA7150 nano-Al2O3 composite. The findings showed that thermal incongruity, Orowan strengthening, the Hall–Petch mechanism, and load transfer effects contributed the most towards the increased strength of the composite. Increasing the nano-Al2O3 wt.% in the AA7150 matrix improved hardness by 95.08%, yield strength by 90.34%, and sliding wear resistance by 46.52%. This enhancement may be attributed to the combined effects of better grain refinement, enhanced dispersion with dislocation strengthening, and better load transfer between the matrix and reinforcement, which are assisted by the inclusion of reinforcements. This result was confirmed by optical studies.

Abstract: Cancer therapy currently focuses on personalized targeted treatments. A promising approach uses stimuli-responsive biomaterials for site-specific drug release, such as pH- and redox-triggered polymer nanocomposites. These materials respond to the tumor microenvironment, enhance efficacy, and reduce off-target effects. Cancer cells with anomalous properties such as acidic cytosolic pH and elevated redox potential are targeted by these biomaterials. An imbalance in ions and biological thiols in the cytoplasm contributes to tumor growth. Functionalized polymer nanocomposites with large surface areas and specific targeting outperform conventional small-molecule materials. To overcome problems such as low bioavailability, uncontrolled drug release, and poor cell penetration, multifunctional nanomaterials make it easier for drugs to enter certain cellular or subcellular systems. High therapeutic efficacy is achieved through surface functionalization, site-specific targeting, and the use of stimuli-responsive components. In particular, pH and redox dual-stimuli-based polymeric nanocomposites for cancer therapeutics have scarcely been reported. This article provides recent progress in pH- and redox-responsive polymer nanocomposites for site-specific drug delivery in cancer therapy. It explores the design principles, fabrication methods, mechanisms of action, and prospects of these dual-stimuli-responsive biomaterials.

Abstract: In recent years, the increase in the generation of agro-food processing waste, coupled with uncontrolled disposal and inefficient recovery methods, has raised concerns among society, industries, and the research community. This issue is compounded by the accumulation of conventional synthetic packaging. Owing to their significant environmental and economic impacts, the development of sustainable, biocompatible, and biodegradable materials has become an urgent target. In this context, research efforts have been directed toward developing new packaging materials based on renewable sources, such as agro-food waste, contributing to the circular economy concept. However, despite significant advances, novel agro-food-waste-based packaging solutions still largely remain at a laboratory scale. This situation highlights the urgent need for further understanding and thorough investigation into how to upscale these products, thereby promoting engagement, investment, and awareness across various fields. This review aims to discuss the current advances in food packaging development using agro-food waste. It covers the main agro-food wastes and by-products currently recovered for sustainable packaging systems through various approaches, such as the extraction of valuable compounds or waste treatments for incorporation into packaging materials, techniques for their valorization, and recent applications of agro-food waste materials in films and coatings. It also addresses the toxicological and safety approaches, challenges, and future perspectives. After an extensive review, we conclude that current research faces challenges in transitioning novel findings to commercial scale, primarily due to safety factors, high production costs, performance deficits, legislative ambiguities, lack of consumer awareness, and inadequate governmental regulations. Consequently, significant investments in research and development appear to be mandatory in the coming years, aiming for optimized, safe, and cost-effective solutions.

Abstract: The escalating global demand for polymer products and the consequent disposal challenge necessitate technological and sustainable solutions. Recent advances in the development of materials used in 3D printing equipment are described in this review, with a focus on new biocomposite materials. The investigation delves into biocomposites comprising PLA and its blends with other polymers, reinforced by plant fibers, with a particular focus on research conducted over the last five years. The information related to the raw materials’ physical, chemical, and processing properties necessary for creating biocomposite filament and printed parts were summarized. The best results in terms of tensile and flexural strength were presented and discussed, signposting future research avenues and desirable objectives. The findings elucidate that the inclusion of plant fibers led to a reduction in mechanical strength relative to pure PLA; however, when smaller particle sizes of plant fibers were added in volumes below 10%, it resulted in improved performance. Moreover, physical and/or chemical pretreatment of fibers, along with the isolation of cellulose fibrils, emerged as pivotal strategies for bolstering mechanical strengths. Noteworthy are the promising prospects presented by the incorporation of additives, while the refinement of printing parameters is key to improving the tensile and flexural strength of printed components.

Abstract: Aluminum matrix composites (AMCs) find extensive use across diverse industries such as automotive, aerospace, marine, and electronics, owing to their remarkable strength-to-weight ratio, corrosion resistance, and mechanical properties. However, their limited wear resistance poses a challenge for applications requiring high tribological performance. Abrasive wear emerges as the predominant form of wear encountered by AMCs in various industrial settings, prompting significant research efforts aimed at enhancing their wear resistance. Over the past decades, extensive research has investigated the influence of various reinforcements on the abrasive wear behavior of AMCs. This paper presents a comprehensive review of the impact of different variables on the wear and tribological response of aluminum composites. This review explores possible wear mechanisms across various tribosystems, providing examples drawn from the analysis of existing literature. Through detailed discussions on the effects of each variable, conclusions are drawn to offer insights into optimizing the wear performance of AMCs.

Abstract: The Resin Transfer Moulding process receives great attention from both academia and industry, owing to its superior manufacturing rate and product quality. Particularly, the progression of its mould filling stage is crucial to ensure a complete reinforcement saturation. Contemporary process simulation methods focus primarily on physics-based approaches to model the complex resin permeation phenomenon, which are computationally expensive to solve. Thus, the application of machine learning and data-driven modelling approaches is of great interest to minimise the cost of process simulation. In this study, a comprehensive dataset consisting of mould filling patterns of the Resin Transfer Moulding process at different injection locations for a composite dashboard panel case study is presented. The problem description and significance of the dataset are outlined. The distribution of this comprehensive dataset aims to lower the barriers to entry for researching machine learning approaches in composite moulding applications, while concurrently providing a standardised baseline for evaluating newly developed algorithms and models in future research works.

Abstract: Hydrogels play a crucial role due to their high-water content and 3D structure, which make them ideal for various applications in biomedicine, sensing, and beyond. They can be prepared from a variety of biomaterials, polymers, and their combinations, allowing for versatility in properties and applications. Hydrogels include natural types derived from collagen, gelatin, alginate, and hyaluronic acid, as well as synthetic types based on polyethylene glycol (PEG), polyvinyl alcohol (PVA), and polyacrylamide (PAAm). Each type possesses distinct properties, such as mechanical strength, biodegradability, and biocompatibility, which can be tailored for applications such as wound healing, contact lenses, 3D bioprinting, and tissue engineering. The high-water content of hydrogels mimics natural tissue environments, promoting cell growth and allowing nutrient and waste exchange, which supports the development of functional tissues. They serve as scaffolds in tissue engineering applications, including wound healing, cartilage and bone regeneration, vascular tissue engineering, and organ-on-a-chip systems. Additionally, hydrogels can encapsulate and deliver therapeutic agents, such as growth factors or drugs, to specific target sites in the body. Hydrogels can be prepared through three primary methods: physical crosslinking, which relies on non-covalent interactions such as physical entanglements or hydrogen bonding; chemical crosslinking, which forms covalent bonds between polymer chains to create a stable structure; and irradiation-based crosslinking, where UV irradiation induces rapid hydrogel formation. The choice of crosslinking method depends on the desired properties and applications of the hydrogel. By providing a biomimetic environment, hydrogels facilitate cell growth and differentiation, support tissue formation, and aid in the regeneration of damaged or diseased tissues while delivering therapeutic agents. This review focuses on the critical advancements in processing routes for hydrogel development, summarizing the characterization and application of hydrogels. It also details key applications, including wound healing and cartilage and bone regeneration, as well as the challenges and future perspectives in the field.

Abstract: The development of efficient waste valorization strategies has emerged as an important field in the overall efforts for alignment with the environmental goals that have been set by the European Union (EU) Green Deal regarding the development of sustainable circular economy models. Additive manufacturing has emerged as a sustainable method for secondary life product development with the main advantages of it being a form of net-zero waste production and having the ability to successfully transport complex design to actual products finding applications in the industry for rapid prototyping or for tailored products. The insertion of eco-friendly sustainable materials in these processes can lead to significant reduction in material footprints and lower energy demands for the manufacturing process, helping achieve Sustainable Development Goal 12 (SDG12) set by the EU for responsible production and consumption. The aim of this comprehensive review is to state the existing progress regarding the incorporation of sustainable polymeric composite materials in additive manufacturing (AM) processes and identify possible gaps for further research. In this context, a comprehensive presentation of the reacquired materials coming from urban and industrial waste valorization processes and that are used to produce sustainable composites is made. Then, an assessment of the printability and the mechanical response of the constructed composites is made, by taking into consideration some key thermal, rheological and mechanical properties (e.g., viscosity, melting and degradation temperature, tensile and impact strength). Finally, existing life cycle analysis results are presented regarding overall energy demands and environmental footprint during the waste-to-feedstock and the manufacturing processes. A lack of scientific research was observed, regarding the manifestation of novel evaluation techniques such as dynamic mechanical analysis and impact testing. Assessing the dynamic response is vital for evaluating whether these types of composites are adequate for upscaling and use in real life applications.

Abstract: The nanocrystalline bismuth oxide (Bi2O3) was produced utilizing a green combustion process with Mexican Mint gel as the fuel. The powder X-ray diffraction (PXRD) method proved the nanocrystalline nature and Bi2O3 nanoparticles (BONPs) in α phase and the average crystalline size of BONPs nanoparticles has been found to be 60 nm. The spherical-shaped structure with bright dot-like spots in the center of the selected area diffraction (SAED) is confirmed by the scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDAX) in conjunction with the transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) demonstrating the crystalline behavior of green NPs. The Kubelka-Monk function was used to analyze diffuse reflectance spectra, and the results revealed that BONPs have a band gap of 3.07 eV. When utilized to evaluate the photocatalytic capabilities of NPs, the direct green (DG) and fast orange red (F-OR) dyes were found to be activated at 618 and 503 nm, respectively. After 120 min of exposure to UV radiation, the DG and F-OR dyes’ photodegradation rate reduced its hue by up to 88.2% and 94%, respectively. Cyclic voltammetry (CV) and electrochemical impedance techniques in 0.1 N HCl were used to efficiently analyze the electrochemical behavior of the produced BONPs. A carbon paste electrode that had been enhanced with BONPs was used to detect the glucose and uric acid in a 0.1 N HCl solution. The results of the cyclic voltammetry point to the excellent electrochemical qualities of BONPs. Bi2O3 electrode material was found to have a proton diffusion coefficient of 1.039 × 10−5 cm2s−1. BONP exhibits significant potential as an electrode material for sensing chemicals like glucose and uric acid, according to the electrochemical behavior.

Abstract: The use of plastic products or components in medical equipment and supplies results in challenges in terms of environmental sustainability and waste management for disposable, non-recyclable, and non-biodegradable materials. Medical plastic waste includes items ranging from syringes, tubing, intravenous (IV) bags, packaging, and more. Developing biodegradable replacements to petroleum-based plastics in medical equipment has not yet become an urgent priority, but it is an important endeavor. Examining alternatives involves several key themes, including material selection, testing, validation, and regulatory approval. To date, research includes studies on biodegradable polymers, composite materials, surface modifications, bacterial cellulose, three-dimensional (3D) printing with biodegradable materials, clinical trials and testing, collaboration with industry, regulatory considerations, sustainable packaging for medical devices, and life cycle analysis. The incorporation of bio-based and biodegradable plastics in the healthcare industry holds immense potential for reducing the environmental impact of medical plastic waste. The literature suggests that researchers and industry professionals are actively working towards finding sustainable alternatives that meet the stringent requirements of the medical industry. This paper reviews the efforts made so far to develop biodegradable and sustainable alternatives to plastic in medical equipment using a meta-analysis of resources, which include relevant papers published in English until June 2024. A total of 116 documents were found and screened by three reviewers for relevance. The literature reviewed indicated that various medical uses require plastics due to their unique properties, such as having strength and flexibility; being lightweight; and being able to prevent bacterial contamination. Among the alternatives, polycaprolactone (PCL), polylactic-co-glycolic acid (PLGA), starch-based acid, and polybutyric acid (PBS) have demonstrated favourable outcomes in terms of biocompatibility, safety, and efficacy. Additionally, a set of approaches to overcome these barriers and strategies is discussed alongside potential future solutions. This review aims to catalyze discussions and actions toward a more environmentally sustainable future in the medical industry by providing a comprehensive analysis of the current state, challenges, and prospects of this domain.

Abstract: The impacts of infill patterns and densities on the mechanical characteristics of items created by material extrusion additive manufacturing systems were investigated in this study. It is crucial to comprehend how these variables impact a printed object’s mechanical characteristics. This work examined two infill patterns and four densities of 3D-printed polyethylene terephthalate reinforced with carbon-fiber specimens for their tensile characteristics. Rectilinear and honeycomb infill designs were compared at 100%, while each had the following three infill densities: 20%, 50%, and 75%. As predicted, the findings revealed that as the infill densities increased, all analyzed infill patterns’ tensile strengths and Young’s moduli also increased. The design with a 75% honeycomb and 100% infill density has the highest Young’s modulus and tensile strength. The honeycomb was the ideal infill pattern, with 75% and 100% densities, providing significant strength and stiffness.

Abstract: This study proposes a method to control the pore-forming process by performing preliminary mechanical activation of the initial rice husk before carbonization. Preliminary mechanical activation of the initial rice husk leads to the loosening of the intercellular substance and its partial depolymerization, thereby increasing the availability of its internal structure for pore formation during carbonization and chemical activation. Using the method described above, nanoporous carbon was obtained with a Brunauer–Emmett–Teller (BET)-calculated specific surface area of 2713 m2/g, a micropore specific surface area calculated by using the Dubinina–Radushkevich (D-R) method of 3099 m2/g, and a total pore volume calculated by using the Barett–Joyner–Halenda (BJH) method of 1.625 cm3/g. Due to these characteristics, the adsorption capacity in the obtained sample was for hydrogen 3.7 wt.% at a temperature of −190 °C and a pressure of 9 kgf/cm2, which is 29.7% higher than the adsorption capacity of nanoporous carbon obtained based on rice husk without mechanical activation. The composite “carbon–platinum” NC-2/Pt10%, at a temperature of 20 °C and a pressure of 9 kgf/cm2, showed an increase in sorption capacity of 27% compared to pure nanoporous carbon NC-2, which is explained by the emergence of the spillover effect.

Abstract: Wound management heavily relies on the vital contribution of wound dressings, emphasizing the significance of finding an ideal dressing that can fulfill the intricate requirements of the wound healing process with multiple functions. A promising strategy is combining several materials and therapies to create multifunctional wound dressings. Nanocomposite hydrogel dressings based on nanomaterials, combining the advantages of nanomaterials and hydrogels in wound treatment, can significantly improve their respective performance and compensate for their shortcomings. A variety of nanocomposite wound dressings with diverse structures and synergistic functions have been developed in recent years, achieving ideal results in wound management applications. In this review, the multiple functions, advantages, and limitations of hydrogels as wound dressings are first discussed. Additionally, the application of inorganic nanomaterials in wound healing is also elaborated on. Furthermore, we focused on summarizing and analyzing nanocomposite hydrogel dressings for wound healing, which contain various inorganic nanomaterials, including metals, metal oxides, metal sulfides, carbon-based nanomaterials, and silicon-based nanoparticles. Finally, prospects for nanocomposite hydrogel wound dressings are envisaged, providing insights for further research in wound management.

Abstract: Compressed gas storage of hydrogen has emerged as the preferred choice for fuel cell vehicle manufacturers, as well as for various applications, like road transport and aviation. However, designers face increasing challenges in designing safe and efficient composite overwrapped pressure vessels (COPVs) for hydrogen storage. One challenge lies in the development of precise software programs that consider a multitude of factors associated with the filament winding process. These factors include layer thickness, stacking sequence, and the development of particularly robust models for the dome region. Another challenge is the formulation of predictive behavior and failure models to ensure that COPVs have optimal structural integrity. The present study offers an exploration of numerical methods used in modeling COPVs, aiming to enhance our understanding of their performance characteristics. The methods examined include finite element analysis in Abaqus, involving conventional shell element, continuum shell element, three-dimensional solid element, and homogenization techniques for multilayered composite pressure vessels. Through rigorous comparisons with type-III pressure vessels from the literature, the research highlights the most suitable choice for simulating COPVs and their practicality. Finally, we propose a new design for type-IV hydrogen composite pressure vessels using one explored method, paving the way for future developments in this critical field.

Abstract: The utilisation of Portland cement has aroused tremendous concerns owing to its production exerting a lot of pressure on the environment. Alternative eco-binders have been developed to replace it, among which alkali-activated materials (AAMs) have drawn great attention, especially due to the possibility of encompassing industrial and agricultural waste, which significantly improves the sustainability and cost-efficiency of the material. Biomass wood ash (BWA) is a by-product generated from power plants and, along with the advocation for biomass fuel as a renewable energy resource, there have been increasing applications of BWA in building and construction materials. This review examines the use of BWA as a precursor source in AAMs. Due to its low chemical and hydraulic reactivity, more active binary precursors are usually introduced to guarantee mechanical properties. Whereas the increment of BWA content can have a negative influence on material strength development, it is still a promising and feasible material, and new approaches should be developed to improve the effectiveness of its utilisation. Currently, study of BWA-based AAMs is still in the beginning stages and more research is needed to investigate the effects of BWA characteristics on the property evolution of AAMs, focusing on the durability and analysis of eco-efficiency. Overall, this review provides a comprehensive overview of the characterisation of BWA and its potential applications in AAMs, and meanwhile, based on the analysis of present research trends, proposes some prospective directions for future research.

Abstract: Food packaging plays an imperative role in the food processing sector by safeguarding foods from their point of harvesting until the moment of consumption. In recent years, biopolymers have attracted the attention of the scientific community as an alternative to conventional packaging materials. Among the available biopolymer sources, a lot of the focus has been on polysaccharides due to their superior barrier properties against gases, oils, and odors and their processing versatility. Moreover, there is also a growing interest in aliphatic polyester as a potential replacement for petrochemical-based synthetic plastics. Both polysaccharides and aliphatic polyesters have gained popularity in sustainable food packaging due to their unique characteristics, including their low cost, availability, biodegradability, gas and moisture barrier properties, film-forming capabilities, excellent heat resistance, and ability to be processed into films, trays, and coatings. This review highlights the structural features, properties, and recent advancements of several vital polysaccharides, namely, starch, chitosan, cellulose, alginate, pectin, carrageenan, and aliphatic polyesters, including polylactic acid (PLA) and polyhydroxybutyrate (PHB) for developing packaging materials, and their applications in the food industry. Conventional packaging and future perspectives of biopolymer-based food packaging are also comprehensively covered in this review.

Abstract: The effective removal of organic dyes from aqueous solutions is of paramount importance in addressing environmental pollution challenges. Methylene blue (MB), a prevalent cationic dye in various industries, has raised concerns due to its persistence and potential adverse effects on ecosystems. This study explores the design, preparation, and characterization of Polycaprolactone–Chitosan (PCL–CH) nanofibers via electrospinning for the removal of MB. PCL, known for its biodegradability and mechanical properties, serves as the primary matrix, while chitosan (CH), with its biocompatibility and amino functionalities, offers enhanced adsorption potential. The electrospinning process yields nanofibers with tailored compositions and controlled morphology. The synthesized nanofibers are systematically characterized, encompassing structural analysis by Fourier transform infrared (FT–IR), spectroscopy, morphology, and composition assessment via Field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS), zeta potential, as well as rheological behavior evaluation. The adsorption uptake of MB onto these nanofibers is investigated, considering the influence of solution pH and initial dye concentration. The results reveal significant enhancements in adsorption capacity, especially with the incorporation of CH, with the PCL–CH 30% nanofibers exhibiting outstanding performance. The pH-dependent behavior underscores the importance of environmental factors in the adsorption process, while higher dye concentrations provide a stronger driving force for adsorption. These findings position PCL–CH nanofibers as promising adsorbents for the efficient removal of MB and potentially other organic contaminants from aqueous solutions. The study contributes to the development of sustainable materials for environmental remediation, wastewater treatment, and related applications, aligning with ongoing efforts to address water pollution challenges.

Abstract: High-Performance Concrete (HPC) and Ultra-High-Performance Concrete (UHPC) have many applications in civil engineering industries. These two types of concrete have as many similarities as they have differences with each other, such as the mix design and additive powders like silica fume, metakaolin, and various fibers, however, the optimal percentages of the mixture design properties of each element of these concretes are completely different. This study investigated the differences and similarities between these two types of concrete to find better mechanical behavior through mixture design and parameters of each concrete. In addition, this paper studied the correlation matrix through the machine learning method to predict the mechanical properties and find the relationship between the concrete mix design elements and the mechanical properties. In this way, Linear, Ridge, Lasso, Random Forest, K-Nearest Neighbors (KNN), Decision tree, and Partial least squares (PLS) regressions have been chosen to find the best regression types. To find the accuracy, the coefficient of determination (R2), mean absolute error (MAE), and root-mean-square error (RMSE) were selected. Finally, PLS, Linear, and Lasso regressions had better results than other regressions, with R2 greater than 93%, 92%, and 92%, respectively. In general, the present study shows that HPC and UHPC have different mix designs and mechanical properties. In addition, PLS, Linear, and Lasso regressions are the best regressions for predicting mechanical properties.

Abstract: The global demand for sustainable building materials has fuelled research into composite panels from wood waste. Despite their potential, the widespread adoption of this practice is hindered by the absence of quality standards, inconsistent material properties, and uncertainties about durability and strength. This paper critically reviews existing standards, manufacturing processes, and the suitability of panels from wood waste. A systematic review is conducted to identify the influencing processes and parameters affecting panel performance, from waste collection to the finishing stages. The findings indicate that incorporating 10–30% of wood waste can enhance the mechanical and physical properties, with particularly improved hygroscopic properties and greater dimensional stability. By establishing comprehensive standards and optimizing manufacturing processes, wood waste-based panels can emerge as a viable and eco-friendly alternative. Furthermore, the potential for repeated recycling in a closed-loop process offers promising environmental benefits, though it necessitates balancing resource conservation with product quality. By addressing these challenges, wood waste-based panels can significantly contribute to environmental conservation and resource management.

Abstract: Embedded sensor technologies have emerged as pivotal tools in redefining structural health monitoring (SHM) within composite materials, addressing a critical need in the composite structure industry. Composites, by their layered nature, are particularly vulnerable to internal delamination and micro-cracks from impacts, which can propagate and lead to catastrophic failures. Traditional inspection methods often fail to detect internal damage and these undetected damages can lead to reduced performance and potential system failures. Embedded sensors offer a solution capable of detecting a spectrum of damages, from barely visible impact damages (BVID) and subtle low-energy impacts to pronounced impact-related deformations, all in real-time. Key sensors, such as Piezoelectric transducers (PZTs), Fiber Bragg Gratings (FBGs), and other potential sensors, have been discussed as potential detection techniques in this review. This review discusses a comprehensive picture of the progress and current scenario of different embedded sensors for SHM of composite structures. The growth of embedded sensor technologies, current limitations, and future requirements focusing on sensor materials have been discussed in this review. Finally, challenges and opportunities for the development of a sustainable SHM system have been discussed in this paper.

Abstract: This work comprehensively investigates the production and characterization of an innovative nanocomposite material and an aluminum matrix reinforced with Al2O3 nanoparticles. The powder metallurgy route was used to produce the nanocomposite, and subsequent microstructural and mechanical characterizations were conducted to evaluate its performance. The nanoparticles and metal powders were dispersed and mixed using ultrasonication, followed by cold pressing and sintering. The results indicated that dispersion using isopropanol made it possible to obtain nanocomposites efficiently through powder metallurgy with a high density and an 88% increase in hardness compared to the Al matrix. The process led to the production of nanocomposites with high densification if the volume fraction of the reinforcement did not exceed 1.0 wt.% of Al2O3. The volume fraction of the reinforcement plays an essential role in the microstructure and mechanical properties of the composite because as it increases to values above 1.0 wt.%, it becomes more difficult to disperse through ultrasonication, which results in less promising results. The addition of Al2O3 significantly affects the Al matrix’s microstructure, which influences the mechanical properties. However, this new approach is proving effective in producing Al matrix nanocomposites with high mechanical properties.

Abstract: The corrosion of steel materials has become a global issue, causing significant socio-economic losses and safety concerns. Hot-dip galvanizing is currently one of the most widely used steel anti-corrosion processes. With the rapid advancement of science and technology and emerging industries, the performance of pure galvanized products struggles to meet the demands of practical applications in various environments. Consequently, researchers have begun introducing various metals into the zinc solution to form high-performance alloy coatings. This article primarily explains the process flow of hot-dip galvanizing and the impact of metal elements such as Al, Mg, Sn, and Bi on the coating, as well as outlining the major issues currently faced by the hot-dip galvanizing process. The objective is to offer a more comprehensive introduction to those new to the field of hot-dip galvanizing and to provide theoretical insights for addressing production issues.

Abstract: The research conducted aimed to investigate the effect of varying print orientation and infill density on the mechanical properties of different 3D printed polymer specimens by conducting tensile tests. The Stratasys Fortus 900mc Material Extrusion printer was used to produce multiple samples of different materials, namely, Acrylonitrile Styrene Acrylate (ASA), Nylon 12, Nylon 12 Carbon Fibre, ULTEM 1010, and ULTEM 9085 which were subjected to tensile tests according to the ASTM D638 standard. Samples were printed in flat, side, and upright orientations with both sparse (50%) and solid (100%) infill densities. The samples were then tensile tested to obtain the Young’s Modulus, ultimate tensile strength (UTS), yield strength, and strain at break. The results produced revealed that the solid infill specimens almost always outperformed the sparse infill specimens. In terms of print orientation, side-orientated specimens achieved higher values for the material properties, followed by the flat specimens, with the upright specimens producing the performance with the lowest values. There were, however, notable exceptions to the results trends mentioned above. These findings were analysed using fracture mechanics and composite theory to explain the unexpected behaviour.

Abstract: The acceleration in advancements of smart materials and non-contact controlled devices in the field of 4D printing is facilitated by the use of magnetically responsive shape memory polymer (SMP) composites. This study is dedicated to the development of promising shape memory materials based on polylactic acid (PLA) and cobalt ferrite (CoFe2O4) nanoparticles. The activation of the shape memory effect (SME) in magnetic nanoparticle composites was achieved by applying a high-frequency alternating magnetic field (HFAMF). The PLA/CoFe2O4 composites exhibited a remarkable shape recovery ratio (>84%) and underwent rapid heating when exposed to HFAMF. The interaction of these composites with mouse adipose-derived mesenchymal stem cells demonstrated adequate cytocompatibility. The rapid magnetosensitive behavior and high shape recovery characteristics of PLA/CoFe2O4 composites make them promising candidates for biomedical applications.

Abstract: Stress shielding is a problem for traditional metal bone fixation plates made of magnesium and titanium alloys. This problem can be solved by using composite materials with a low elastic modulus. This study analyzed the effect of carbon fiber reinforced PEEK (CFRP) composites on stress shielding under static loading using finite element simulations. Callus formation times relative to the healing period were gradually imposed according to the elapsed time, considering 1% and 75% as healing stages. The Inventor© 3D CAD 2024 software was used for modeling, and the ANSYS© FEA R2023 software was used for analysis. The results showed that metal fixation plates made of titanium and magnesium alloys transferred less stress to the bone than the CFRP fixation plate. In particular, the use of the CFRP fixation plate resulted in a higher peak stress and a more uniform stress field in the bone, especially in the bone-plate contact area, where the risk of stress shielding is higher in the 1% and 75% healing phases.

Abstract: In this work, novel multifunctional electrospun nanofibrous membranes made of polyamide (PA6) and loaded with silica (SiO2) and/or titanium dioxide (TiO2) nanoparticles were fabricated. SiO2 NPs were first prepared and then characterized by TEM, FE-SEM, and FTIR, and by using XRD techniques, confirming the formation of cristobalite tetragonal crystals with high purity. Different nanofibrous mats, loaded with SiO2 NPs, TiO2 NPs, or both SiO2 and TiO2 NPs, were investigated. Morphological studies indicated that SiO2 and TiO2 nanoparticles tend to be arranged along the fiber surface, also promoting the formation of anatase nanorods when they are mixed into the nanofibers. In this last scenario, mechanical tests have demonstrated that the presence of SiO2 contributed to balancing the mechanical response of fibers that are negatively affected by the presence of TiO2 NPs—as confirmed by tensile tests. More interestingly, the presence of SiO2 did not negatively affect the antibacterial response against different bacteria populations (i.e., Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, Bacillus subtilis, and Candida albicans), which is mainly ascribable to the presence of TiO2 particles. Accordingly, the TiO2- and TiO2/SiO2-loaded fibers showed higher methylene blue (MB) absorption values—i.e., 26 mg/g and 27 mg/g—respectively, compared to the SiO2-loaded fibers (23 mg/g), with kinetics in good agreement with the second-order kinetic model. The obtained findings pave the way for the formation of novel antibacterial membranes with a promising use in water purification.

Abstract: Biochar, an organic, porous, and carbon-rich material originating from biomass via pyrolysis, showcases compelling attributes and intrinsic performances. Its appeal as a reinforcement material for biocomposites, as well as its auspicious electrical properties, has gained more attention, and makes biochar a versatile candidate for applications ranging from energy storage to catalytic devices. This scientific review undertakes a comprehensive exploration of biochar, spanning production methodologies, physicochemical intricacies, and critical process parameters. The focus of this paper extends to optimization strategies for biochar properties tailored to specific applications, with a dedicated inquiry into diverse production methods and activation strategies. This review’s second phase delves into a meticulous analysis of key properties within biochar-based composites, emphasizing limitations and unique performance characteristics crucial for diverse applications. By synthesizing a substantial body of research, this review aims to catalyze future investigations by pinpointing areas that demand attention in upcoming experiments, ultimately emphasizing the profound potential of biochar-based materials across technical and scientific domains.

Abstract: Three-dimensional printing technology holds significant potential for enhancing the flexibility and cost-efficiency of producing carbon fiber-reinforced polymer composites (CFRPs). However, it faces limitations such as challenges in achieving high surface qualityand precise dimensional accuracy and managing the distinctive anisotropic mechanical properties that it demonstrates. This study aims to explore the machinability of 3D printed PETG infused with 20% short carbon fiber and to assess the resulting surface roughness and burr formation. Employing a Design of Experiments (DoE) approach, three factors were considered: rotational speed, feed rate, and depth of cut. These factors were tested at varying levels—rotational speeds of 3000, 5500, and 8000 rpm; feed rates of 400, 600, and 800 mm/min; and depth of cut values of 0.2, 0.4, 0.6, and 0.8 mm. The evaluation of machinability relied on two key response parameters: surface roughness (Sa) determined from the milled surface and burr height measured on both sides using a roughness meter. The findings revealed a significant influence of milling parameters on both roughness and burr formation. However, the ideal conditions for minimizing roughness and reducing burr formation did not align. Furthermore, a comparative analysis was conducted between these results and the machinability of PETG under similar conditions.