Search Results (8,074)

The escalating release of synthetic dyes from textile and allied industries has become a pressing global environmental issue due to their toxicity, persistence, and resistance to biodegradation. Among the various treatment strategies, adsorption has emerged as one of the most efficient, economical, and sustainable techniques for dye removal from aqueous environments. This review highlights recent advances in bio-derived adsorbents—particularly raw biomass powders, biochars, and activated carbons—developed from renewable waste sources such as agricultural residues, fruit peels, shells, and plant fibers. It systematically discusses adsorption mechanisms, the influence of process parameters, kinetic and thermodynamic models, and regeneration performance. Furthermore, the review emphasizes the superior adsorption efficiency and cost-effectiveness of biomass-derived carbons compared to conventional adsorbents. The integration of surface modification, magnetization, and nanocomposite formation has further enhanced dye uptake and reusability. Overall, this study underscores the potential of biomass-derived materials as sustainable alternatives for wastewater treatment and environmental remediation. Full article

The advancement of reactive powder concrete (RPC) technology primarily focuses on modifications to its conventional composition. This involves substituting Portland cement (CEM I) with alternative cement types and finely ground mineral additives, as well as replacing quartz aggregate with another type of aggregate. The paper presents an analysis of the properties of RPC obtaining using waste sand and powder generated during the processing of aggregates from migmatite-amphibolite rock. Research into RPC mixtures revealed that in one scenario, replacing quartz powder with waste powder resulted in a significant increase in flexural strength by 23%, although there was a slight decrease in compressive strength by 7%. However, when both quartz powder and quartz sand were substituted with waste powder and waste sand, there was a 14% reduction in compressive strength, while flexural strength increased, albeit to a much lesser extent. The analysis of mineral composition and microstructure of migmatite-amphibolite waste powder and sand revealed that the primary factor contributing to the increase in flexural strength is the presence of biotite in a flake shape form. The microscopy images clearly show hydration products gathering mainly at the rims of biotite flakes and not on their smooth surfaces. The reason could be better availability for hydration products attachment and lower steric hindrance to the rims of single biotite flakes instead of its large packets. Conversely, the reduction in RPC compressive strength, resulting from the substitution of quartz sand with migmatite-amphibolite waste sand, can be attributed mainly to the lower compressive strength of the waste sand itself. Test results indicate that the waste powder generated during the production of migmatite-amphibolite aggregates, which contains fine flakes of biotite, can be utilised as a mineral admixture in concrete, thereby enhancing its flexural strength. Full article

Façades account for approximately 15–20% of a building’s embodied carbon, making them a key target for material decarbonization. While bio-composites are increasingly explored for façade insulation, cladding systems remain dominated by carbon-intensive materials such as aluminum and fiber-reinforced polymers (FRPs). This paper presents findings from a study investigating the use of food-waste-derived bulk fillers in bio-composite materials for façade cladding applications. Several food-waste streams, including hazelnut and pistachio shells, date seeds, avocado and mango pits, tea leaves, and brewing waste, were processed into fine powders (<0.125 μm) and combined with a furan-based biobased thermoset resin to produce flat composite sheets. The samples were evaluated through mechanical testing (flexural strength, stiffness, and impact resistance), water absorption, freeze–thaw durability, and optical microscopy to assess microstructural characteristics before and after testing. The results reveal substantial performance differences between waste streams. In particular, hazelnut and pistachio shell fillers produced bio-composites suitable for façade cladding, achieving flexural strengths of 62.6 MPa and 53.6 MPa and impact strengths of 3.42 kJ/m² and 1.39 kJ/m², respectively. These findings demonstrate the potential of food-waste-based bio-composites as low-carbon façade cladding materials and highlight future opportunities for optimization of processing, supply chains, and material design. Full article

Directed Energy Deposition-Laser (DED-L) enables high-performance coatings through melting and successive powder deposition. Its compositional flexibility suits functionally graded layers that enhance corrosion and wear resistance. This study aimed to improve parameters for producing dense, defect-free, graded Ni- and Fe-based coatings by varying the scanning speed and deposition strategy (monodirectional versus bidirectional, with/without layer rotation), while keeping the power and hatch distance constant. Laser and electron microscopy were used to link parameters to porosity and uniformity. Optimal settings minimized pores, improved interlayer bonding and preserved geometry; inadequate parameters yielded porous, irregular deposits. A bidirectional path with 90° rotation appeared best. Ongoing research activities are needed to assess its properties. Full article

Additive manufacturing (AM) has emerged as a key enabling technology in contemporary dental manufacturing, driven by its capacity for customization, geometric complexity, and seamless integration with digital design workflows. This article presents a technology-oriented narrative review of additive manufacturing in dental implant production, focusing on dominant processing routes, material systems, and emerging research trends rather than a systematic or critical appraisal of the literature. An indicative descriptive analysis of publications indexed in the Web of Science and Scopus databases between 2014 and 2024 was used to contextualize the technological development of the field and identify major research directions. Emphasis was placed on metal powder bed fusion technologies, specifically Selective Laser Melting (SLM) and Direct Metal Laser Sintering (DMLS), which enable the fabrication of titanium implants with controlled porosity and enhanced osseointegration. Ceramic AM approaches, including SLA, DLP, and PBF, are discussed in relation to their potential for aesthetic dental restorations and customized prosthetic components. The publication trend overview indicates a growing interest in ceramic AM after 2020, an increasing focus on hybrid and functionally graded materials, and persistent challenges related to standardization and the availability of long-term clinical evidence. Key technological limitations—including manufacturing accuracy, material stability, validated metrology, and process reproducibility—are highlighted alongside emerging directions such as artificial intelligence-assisted workflows, nanostructured surface modifications, and concepts enabling accelerated or immediate clinical use of additively manufactured dental restorations. Full article

In this work, samples of 30KhGS steel coated by thermal spray were investigated. The coating procedure consisted of two stages. At the first stage, a powder mixture of Cu + Al (mass ratio 4:1) was deposited. At the second stage, under the same process parameters, TiC powder was applied. After each spraying stage, the structure, elemental composition and stress state of the coatings were examined. Following the second deposition, hardness and wear resistance of the sample were measured. The results showed that the hardness and wear resistance of the test specimen increased on average by 40% compared to the corresponding properties of 30KhGS steel subjected to quenching and tempering. The residual stress level in the first (lower) coating was higher than in the upper layer; this difference is related to the distinct mechanisms of layer formation. The lower layer forms through melting and subsequent solidification, whereas the top layer forms by liquid-phase sintering. The obtained results demonstrate the effectiveness of the two-layer coating for increasing the hardness and wear resistance of 30KhGS steel, which broadens the possibilities for surface restoration and repair of parts. Full article

This study reports the fabrication and characterization of copper–silicon carbide (Cu–SiC) metal matrix composites produced using powder metallurgy (PM) combined with thermo-compression processing (TCP), a dual route that remains limited in Cu–SiC research. Micro-sized SiC particles (1–25 wt.%) were incorporated into Cu, compacted, sintered, and subsequently subjected to sequential forging and annealing. Unlike conventional PM-only processing, TCP significantly reduced porosity, promoted more uniform reinforcement dispersion, and relieved residual stresses, creating a strong synergy between densification and microstructural refinement. SEM, EDS, XRD, and Raman analyses confirmed phase stability, homogeneous reinforcement distribution, and the absence of deleterious interfacial phases. The integrated PM + TCP route achieved an ultimate tensile strength of ~209 MPa, hardness of ~65 HRB, and toughness of ~35 MJ/m³ at approximately 3 wt.% SiC. The superior performance at this composition resulted not from the lowest porosity but from the combined effects of uniform particle dispersion, improved particle–matrix bonding, and deformation-driven refinement. These findings establish TCP as an effective post-sintering strategy that overcomes intrinsic porosity and interfacial limitations in Cu–SiC composites. Overall, powder metallurgy combined with the thermo-compression processing is identified as a promising processing pathway for developing high-strength, thermally stable Cu–SiC materials for structural and thermal management applications. Full article

Nickel–Aluminum–Bronze (NAB) has gained significant attention in marine applications due to its excellent corrosion resistance and has shown growing potential for laser powder bed fusion (L-PBF) additive manufacturing. However, research on the fabrication of NAB alloys using L-PBF remains relatively limited. In this study, fully dense NAB samples were successfully fabricated through L-PBF process parameter optimization. The microstructural evolution and mechanical properties of both as-built and annealed L-PBF samples were systematically investigated and compared with those of traditionally cast NAB. The results reveal that the as-built L-PBF specimens primarily consist of columnar β′ grains, with the α phase distributed along the grain boundaries and a small amount of κ phase precipitated within the β′ matrix, distinctly different from the cast microstructure characterized by a columnar α-phase matrix with precipitated β′ and κ phases. After annealing at 675 °C for 6 h, the β′ phase in both methods decomposed into α + κ phases, and the original columnar structure in the L-PBF specimens transformed into a dendritic morphology. Compared to the cast samples, the L-PBF-produced NAB alloy exhibited significantly enhanced yield strength, tensile strength, and microhardness, attributable to rapid solidification during the L-PBF process. Following annealing, the yield strength and elongation increased by 12.8% and 184.4%, respectively, compared to the as-built condition, resulting from the decomposition of the martensitic phase into α + κ phases and further grain refinement. Full article

This study presents the first application of Machine Learning (ML) models to optimise Powder Bed Fusion using Laser Beam (PBF-LB) process parameters for H13 steel fabricated on a 350 °C preheated building platform. A total of 189 cylindrical specimens were produced for training and testing machine learning (ML) models using variable process parameters: laser power (250–350 W), scanning speed (1050–1300 mm/s), and hatch spacing (65–90 $\mathsf{\mu }$m). Eight ML models were investigated: 1. Support Vector Regression (SVR), 2. Kernel Ridge Regression (KRR), 3. Stochastic Gradient Descent Regressor, 4. Random Forest Regressor (RFR), 5. Extreme Gradient Boosting (XGBoost), 6. Extreme Gradient Boosting with limited depth (XGBoost LD), 7. Extra Trees Regressor (ETR) and 8. Light Gradient Boosting Machine (LightGBM). All models were trained using the Fast Library for Automated Machine Learning & Tuning (FLAML) framework to predict the relative density of the fabricated samples. Among these, the XGBoost model achieved the highest predictive accuracy, with a coefficient of determination $R^2=0.977$, mean absolute percentage error MAPE = 0.002, and mean absolute error MAE = 0.017. Experimental validation was conducted on 27 newly fabricated samples using ML predicted process parameters. Relative densities exceeding 99.6% of the theoretical value (7.76 g/cm³) for all models except XGBoost LD and KRR. The lowest MAE = 0.004 and the smallest difference between the ML-predicted and PBF-LB validated density were obtained for samples made with LightGBM-predicted parameters. Those samples exhibited a hardness of 604 ± 13 HV0.5, which increased to approximately 630 HV0.5 after tempering at 550 °C. The LightGBM optimised parameters were further applied to fabricate a part of a forging die incorporating internal through-cooling channels, demonstrating the efficacy of machine learning-guided optimisation in achieving dense, defect-free H13 components suitable for industrial applications. Full article

Insomnia remains a widespread global health issue, and traditional hypnotic drugs often produce adverse effects. Although spinosin in Ziziphi Spinosae Semen has sleep-promoting effects, its use is limited by poor solubility and low oral bioavailability. In this study, the solvent melt method was used to prepare spinosin solid dispersions, optimising the process with an L₉(3⁴) orthogonal design based on apparent solubility. In vitro dissolution testing showed that solid dispersions of varying particle sizes dissolved more readily than pure spinosin, with smaller particles exhibiting faster dissolution. Cellular uptake was assessed in human colon adenocarcinoma cells, with results revealing enhanced uptake of smaller-particle solid dispersions. Powder X-ray diffraction confirmed that spinosin transformed from a crystalline to an amorphous state in the dispersion system. A quadratic orthogonal experiment was conducted to optimise functional dairy beverage formulation, using the centrifugal sedimentation rate as the evaluation index. In vivo experiments demonstrated that the resulting functional dairy beverage reduced spontaneous activity in mice, achieved a 60% sleep-onset rate, improved ethanol-induced memory impairment and produced marked sleep-promoting effects. Moreover, pharmacokinetic studies confirmed that the spinosin solid-dispersion-based functional dairy beverage significantly enhanced the systemic exposure and oral bioavailability of spinosin compared to the spinosin water suspension. These findings indicate that solid dispersion technology effectively enhances spinosin solubility and that the developed functional dairy beverage shows promise as a sleep-promoting functional food. Full article

Valorization of black carrot pomace (BCP), an industrial by-product rich in bioactive compounds, was performed using sustainable extraction and formulation approaches. Bioactive compounds were extracted, using water as a solvent, via ultrasonic processing. The resulting liquid extract (BCP-E) was then freeze-dried with a gum Arabic gel system to obtain a powder formulation (FD-BCP). The technological, physicochemical, and bioactive characteristics of both formulations are described. Total monomeric anthocyanin and antioxidant activities (DPPH and ABTS) did not differ substantially (p > 0.05), but the liquid extract’s total phenolic content was significantly higher (4.95 mg GAE/g db) than the powder formulation’s (4.46 mg GAE/g db). While FD-BCP had three main hydrophilic phenolic compounds, suggesting partial encapsulation, high-resolution LC-MS analysis identified 21 phenolic compounds in BCP-E, dominated by chlorogenic, quinic, and protocatechuic acids. The development of a stable gum Arabic matrix that maintains the phenolics’ structural integrity was confirmed by SEM and FTIR observations. According to cytotoxicity tests conducted on L929 fibroblast cells, both formulations were biocompatible (>70% viability) and even stimulated cell growth at moderate dosages. Dose- and time-dependent viability patterns were successfully described by Principal Component Analysis and Artificial Neural Network models, highlighting the fact that formulation type is the main factor influencing biological response. Overall, ultrasonic extraction and freeze-drying offer efficient and sustainable strategies for producing stable and bioactive-rich components from black carrot pomace that may be used in functional foods and biomedical products. Full article

This study reports the fabrication of copper-based metal matrix composites reinforced with a combination of micro- and nano-sized titanium carbide (TiC) particles using the powder metallurgy route. The micro-TiC content was maintained at 5 wt.%, while the nano-TiC addition was systematically varied between 1 and 3 wt.% in increments of 1 wt.%. The consolidation of the blends was achieved by uniaxial compaction at 500 MPa, followed by sintering in a nitrogen atmosphere at 750–900 °C for 2 h. Tribological assessment under dry sliding conditions was performed using a pin-on-disk apparatus. Structural and microstructural examinations using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) confirmed a uniform incorporation of the reinforcements within the Cu matrix. The incorporation of nano-TiC up to 2 wt.% significantly enhanced density, hardness, and wear resistance, after which a marginal decline was observed. SEM analysis of worn surfaces revealed that adhesive wear, abrasion, and delamination were the primary wear mechanisms. To better understand the relationship between processing conditions and material responses, response surface methodology (RSM) was employed. The developed models for density, hardness, and wear loss showed good agreement with the experimental results, with confirmatory tests yielding errors of 1.59%, 2.06%, and 2%, respectively, thereby validating the approach’s reliability. Full article

CO₂ emissions continue to rise, along with the associated environmental risks. In response, the United Nations has been promoting the adoption of sustainable practices among businesses worldwide. In parallel, an innovative technology known as additive manufacturing (AM) has emerged over the past four decades. This technology has the potential to be more sustainable than conventional manufacturing (CM) technologies. When metals are used as the material, the process is referred to as metal additive manufacturing (mAM). AM technologies have seven process categories, which include metal mAM processes, most notably powder bed fusion (PBF), directed energy deposition (DED), binder jetting (BJT), material extrusion of metal-filled feedstock, and sheet lamination. Among these, PBF and DED are by far the most widely applied metal AM technologies in both industrial practice and academic research. The use of mAM is increasing; however, is it truly more sustainable than CM? Motivated by this question, a systematic literature review (SLR) was conducted to compare the sustainability impacts of mAM and CM across the three dimensions of sustainability: environmental, economic, and social. The evidence shows mixed sustainability outcomes, which are synthesized later in the conclusions. The sustainability comparison is influenced by factors like part redesign with topological optimization (TO), the material and energy mix used, geometric complexity, production volume per batch, and the boundaries adopted. Economic viability remains critical; companies are unlikely to adopt mAM if it proves more expensive than CM as this could threaten its competitiveness. Social impacts are the least studied dimension, and it is difficult to anticipate the changes that might occur because of such a transition. Full article

Fruit peels, a primary fruit processing by-product, are rich in biodegradable polymers (e.g., dietary fibers and proteins) and bioactive substances (e.g., polyphenols, essential oils, and pigments) that are suitable for producing active and intelligent packaging films. In recent years, there is a new trend to utilize fruit peels in the form of powders for film production, which aligns with circular economy principles. In general, fruit peel powders (FPPs) can function as rigid fillers and the polymer matrix in packaging films, forming FPP-filled and FPP-based films, respectively. These two film types exhibit distinct characteristics: FPP-filled films typically have a compact structure with strong molecular interactions, leading to superior mechanical and barrier properties. Conversely, FPP-based films often display a cracked structure with weaker molecular interactions, resulting in inferior mechanical and barrier properties. Despite these differences, both film types demonstrate excellent antioxidant and antimicrobial activities, pH sensitivity, and biodegradability, as well as considerable promise for active and intelligent packaging. This review comprehensively summarizes the preparation methods, structural characteristics, physical and functional properties, and active and intelligent packaging potential of both film types. It also features a multi-dimensional comparison of FPP-filled and FPP-based films’ performance and a discussion of their current challenges and future directions. Full article

A vacuum-arc pulsed plasma accelerator (APPA) operating at a discharge current of 750 A and a pulse duration of 110 μs with a repetition rate of 5 Hz was employed to deposit thin films and coatings under low- and medium-vacuum conditions. The aim of this study was to obtain metal coatings suitable for potential applications in the energy and chemical industries. SEM, AFM, and XRD techniques were used to investigate the structure and morphology of coatings formed on metallic and insulating substrates under the following conditions: residual pressure of 10⁻²–10⁻⁴ mbar and deposition times of 10–30 min. Under medium-vacuum conditions, thin and non-uniform metallic films with thicknesses ranging from 0.4 to 1.9 μm were deposited on metal substrates. The morphology of thick films deposited under low-vacuum conditions consisted of spherical metal particles of various sizes (0.1–1 μm), containing up to 30% carbon and 28% oxygen. On silicon substrates, spherical microparticles up to 4 μm in diameter with thin shells approximately 0.3 μm thick were formed. One possible mechanism for microsphere formation—the desorption of residual gases by the coating material—is discussed. The potential of the APPA method for producing metal shells, relevant to powder manufacturing due to the high energy density of the process and the intrinsic purity of vacuum technologies, is also considered. Porous coatings obtained using the APPA technique may be applicable in the fabrication of energy-related materials, such as battery anodes. Full article