Search Results (10,020)

In the present paper, the interaction between metal oxide nanoparticles and carbon materials was studied, and the results showed a synergetic effect, leading to an improvement in the properties of the obtained hybrid composites. The In₂O₃ NPs were prepared by the precipitation method and thermal treatment at 550 °C. The composites were obtained using an ex situ method, by mixing the In₂O₃ NPs with reduced oxide graphene (rGO) in a ratio of 10:1. The structural, morphological, and chemical composition studies of the In₂O₃ NPs and In₂O₃-rGO composites were investigates by FTIR and EDX spectroscopy, SEM microscopy, and XRD analysis. These techniques have highlighted the obtaining of In₂O₃ of high purity, and crystallinity, with the mean particle size in the range of 8–25 nm, but also, the dispersion of In₂O₃ NPs onto rGO sheets. We examined the influence of the In₂O₃ nanostructure morphology and In₂O₃-rGO composites on the electrochemical properties using cyclic voltammetry. The surface properties of the In₂O₃ and composite films were studied by contact angles, which indicate the maintenance of the hydrophilic nature. The obtained results establish the synergy between the main components to form In₂O₃-rGO, which can be used for the development of biosensors to enhance the device performance. Full article

A friction composite material which contains cellulose fiber, carbon fiber, wollastonite, graphite, and resin for use in oil-cooled friction units, hydromechanical boxes, and couplings was developed. The fabrication technique includes the formation of a paper layer based on the mixture of stated fibers via a wet-laid process, impregnation of the layer with phenolic resin, and hot pressing onto a steel carrier. The infrared spectra of the polymeric base (phenolic resin) were studied by solvent extraction. The structural-phase analysis of the obtained material was carried out by the SEM method, and the particle size distribution parameters of the composite components were estimated based on the images of the sample surface. The surface roughness parameters of the samples are as follows: Ra = 5.7 μm Rz = 31.4 μm. The tribotechnical characteristics of the material were tested in an oil medium at a load of 5.0 MPa and a rotation mode of 2000 rpm for 180 min in a pair with a steel 45 counterbody. The coefficient of friction of the developed material was 0.11–0.12; the degree of wear was 6.17 × 10⁻⁶ μm/mm. The degree of compression deformation of the composite is 0.36%, and the compressive strength is 7.8 MPa. The calculated kinetic energy absorbed and power level are 205 J/cm² and 110 W/cm², respectively. The main tribotechnical characteristics of the developed friction material correspond to industrial analogues. Full article

Laser-Directed Energy Deposition (L-DED) is an additive manufacturing technique used for producing and repairing components, mainly for coating applications, depositing metal matrix composites such as cemented carbides, composed of hard metal carbides and a metallic binder. In this sense, this study evaluated the preparation of a ready-to-press WC-25Co powder as a reliable feedstock for L-DED process. This powder required pre-heat treatment studies to prevent fragmentation during powder feeding, due to the absence of metallurgical bonding between WC and Co particles. In the current study, the Taguchi methodology was used, varying laser power, powder feed rate, and scanning speed to reach an optimised deposition window. The best bead morphology resulted from 2400 W laser power, 11 mm/s scanning speed, and 9 g/min feed rate. Moreover, defects such as porosity and cracking were mitigated by applying a remelting strategy of 2400 W and 9 mm/s. Therefore, a perfect deposition is obtained using the optimised processing parameters. Microstructural analysis of the optimised deposited line revealed a fine structure, comprising columnar and equiaxed dendrites of complex carbides. The average hardness of the deposited WC-25Co powder on a AISI 1045 steel was 854 ± 37 HV0.2. These results demonstrate the potential of L-DED for processing high-performance cemented carbide coatings. Full article

Despite aesthetic trends, metal–ceramic restorations continue to be widely accepted due to their durability, and variations in surface preparation process can significantly influence bond strength outcomes. The purpose of this study was to determine whether there are differences in the bond strength depending on three surface treatment protocols for veneering ceramics on Ni-Cr alloys. The following surface treatments were used: (1) control (C) (no treatment), (2) airborne-particle abrasion (APA) with 50 µm Al₂O₃ (G1-APA), (3) APA followed by oxidation (G2-APA-O), and (4) APA-O, with a second APA (G3-APA-O-APA). Subsequently surface roughness (R_a and R_z) was evaluated using profilometry, hardness was measured through Leeb’s hardness dynamic test (HLD), morphology was investigated through scanning electron microscopy (SEM), and the chemical composition of the alloy surface was evaluated using energy-dispersive spectroscopy (EDS). After surface treatments, veneering ceramic was applied, the debonding crack initiation strength (DCIS) was investigated through the three-point bending test, failure mode was classified using a stereoscopic microscope, and chemical characterization of the fractured surfaces was performed using Raman spectroscopy (RS). For DCIS, G2-APA-O demonstrated the highest value 63.97 ± 44.40 (MPa) (p < 0.05). The results of this study indicate that oxidation treatment has a positive effect on the bonding strength between veneering ceramic and Ni-Cr alloys. Full article

In this study, alkali-treated wood flour/dynamic polyurethane composites were successfully prepared through a solvent-free one-pot method and in situ polymerization. The effects of the alkaline treatment process, changes in the flexible long-chain content in the dynamic polyurethane system, and the wood flour filling amount on the interface’s bonding, mechanical, and reprocessing properties were investigated. Partial removal of lignin and hemicellulose from the alkali-treated wood flour enhanced rigidity and improved interface bonding and mechanical strength when combined with dynamic polyurethane. The tensile strength was improved from 5.65–11.00 MPa to 13.08–23.53 MPa. As the composite matrix, dynamic polyurethane could not easily infiltrate all wood flour particles when its content was low or its fluidity was poor. Conversely, excessive content or overly high fluidity led to leakage and the formation of large pores, affecting the mechanical strength. As the polyol content increased, the matrix exhibited greater fluidity, which enabled it to accommodate more wood flour and penetrate the cell cavity or even the cell wall. This improved infiltration enhanced the interface bonding performance of the composites and made their mechanical properties sensitive to changes in wood flour content. The reprocessing ability of the prepared composites decreased with the increase in wood flour content, and the interface bonding was enhanced after reprocessing. The tensile strength retention rate of the composites prepared with alkali-treated wood flour was lower. This study provides a theoretical basis for optimizing the performance of wood fiber/dynamic polyurethane composites and an exploration path for developing self-healing and recyclable wood–plastic composites, which can be applied to building materials, automotive interiors, furniture manufacturing, and other fields. Full article

Particulate matter (PM), a complex mixture of solid particles and liquid droplets, originates from both natural sources, such as sand, pollen, and marine salts, and anthropogenic activities, including vehicle emissions and industrial processes. While PM itself is not inherently toxic in all its forms, it often acts as a carrier of xenobiotic toxicants, such as heavy metals and organic pollutants, which adhere to its surface. This combination can result in synergistic toxic effects, significantly enhancing the potential harm to biological systems. Due to its small size and composition, PM can penetrate deep into the respiratory tract, acting as a physical “shuttle” that facilitates the distribution and bioavailability of toxic substances to distant organs. The omnipresence of PM in the environment leads to unavoidable and constant exposure, contributing to increased morbidity and mortality rates, particularly among vulnerable populations like the elderly, children, and individuals with pre-existing health conditions. This exposure also imposes a substantial financial burden on healthcare systems, as treating PM-related illnesses requires significant medical resources and leads to higher healthcare costs. Addressing these challenges necessitates effective mitigation strategies, including reducing PM exposure, improving air quality, and exploring novel approaches such as AI-based exposure prediction and nutritional interventions to protect public health and minimize the adverse effects of PM pollution. Full article

This paper presents a combined approach to the synthesis of WC-(Fe, Ni) hard alloys obtained by mechanical activation and spark plasma sintering (SPS). The main attention at this stage of the work is paid to studying the evolution of the morphology and phase composition of WC-(Fe, Ni) powder mixtures during high-energy milling and their subsequent sintering by the SPS method. The study analyzed the effect of the mechanosynthesis time and the binder phase content on the change in the average particle size, the degree of defect formation, and the phase composition of the powders. It was found that an increase in the milling time to 240 min promotes the formation of the WC nanocrystalline structure and the accumulation of microdefects, which is accompanied by a decrease in the average particle size and an increase in the dislocation density. The X-ray phase analysis of the samples after SPS confirmed the preservation of the WC phase and the formation of the γ-(Fe, Ni) matrix without the formation of secondary carbide phases. The analysis of sample shrinkage showed three main stages: initial compaction, intense shrinkage, and structure stabilization. The obtained data demonstrate that optimization of the parameters of mechanical activation and SPS allow for effective control of the phase composition and morphology of WC-(Fe, Ni) powders, which opens up opportunities for their subsequent study in conditions of aggressive environments and radiation exposure. Full article

Cancer remains one of the most pressing global health challenges, driving the need for innovative treatment strategies. Boron neutron capture therapy (BNCT) offers a highly selective approach to destroying cancer cells while sparing healthy tissues. To improve boron delivery, Fe₃O₄@Au nanoparticles were developed and functionalized with a boron-containing carborane compound. Fe₃O₄ nanoparticles were synthesized and covered by gold, followed by (3-Aminopropyl)triethoxysilane (APTES) modification to introduce amino groups for carborane immobilization. Comprehensive characterization using SEM, DLS, FTIR, EDX, Brunauer–Emmett–Teller (BET), and XRD confirmed successful functionalization at each stage. TEM confirmed the final structure and elemental composition of the nanoparticles. BET analysis revealed a surface area of 94.69 m²/g and a pore volume of 0.51 cm³/g after carborane loading. Initial release studies in PBS demonstrated the removal of only loosely bound carborane within 48 h, with FTIR confirming stable retention of the compound on the nanoparticle surface. The modified nanoparticles achieved a stable zeta potential of −20 mV. The particles showed low toxicity within a range of concentrations (0–300 μg Fe/mL) and were efficiently accumulated by U251MG cells. These results demonstrate the potential of the obtained nanoparticles to carry boron and gold for their possible application as a theranostic agent. Full article

The search for a simple, scalable, and eco-friendly method for synthesizing micro-sized photocatalysts is an urgent task. Plasma technologies are highly effective and have wide possibilities for targeted synthesis of novel materials. The mass-average temperature of plasma treatment is higher than the stability temperature of anatase and brookite, the most photoactive polymorphs of titanium dioxide. In this work, by optimizing the plasma treatment conditions and selecting source materials, a method for synthesizing micro-sized photocatalyst based on heterocomposite TiO₂/ZnO particles with high anatase content is proposed. The synthesis method involves treating a powder mixture of titanium and zinc by low-temperature argon plasma under atmospheric conditions. The relationship between the structural-phase composition, morphology, and photocatalytic properties of the microparticles was investigated. A model for the synthesis of composite microparticles containing anatase, rutile, and heterostructural contact with zinc oxide is proposed. The photocatalytic degradation of methylene blue and metronidazole was studied to evaluate both sensitized and true photocatalytic processes. The metronidazole degradation confirmed the intrinsic photocatalytic activity of the synthesized composites. Additionally, the features of photocatalysis under UV and solar irradiation were studied, and a photocatalysis mechanism is proposed. The synthesized micro-sized heterocomposite photocatalyst based on TiO₂/ZnO contained anatase (36%), rutile (60), and brookite (4%) and showed a photocatalytic activity during the methylene blue degradation process under UV irradiation (high-pressure mercury lamp, 250 W): 99% in 30 min. Full article

To enhance the wear resistance of laser-clad coatings, this study investigates the underlying modulation mechanisms of scanning speed on the microstructure and properties of TiC-TiB₂-reinforced 316L stainless steel composite coatings. TiC/TiB₂ particle-reinforced 316L stainless steel composite coatings were fabricated on 45# steel substrates via laser cladding. Our analysis reveals that scanning speed critically governs the thermal cycle of the melt pool, thereby modulating the coating’s microstructure and properties: Lower scanning speeds prolong melt pool duration, consequently intensifying ceramic particle dissolution, coarsening, and tendencies toward agglomeration and settling. Conversely, higher scanning speeds promote rapid solidification, which both preserves ceramic particles and refines the matrix grains. With increasing scanning speed, accelerated melt pool cooling rates drive a microstructural transition from coarse dendrites to refined equiaxed grains, accompanied by dramatically enhanced uniformity in ceramic particle distribution. Coatings deposited at higher scanning speeds exhibit a 22% increase in hardness compared to those at lower speeds. Wear resistance evolution parallels this hardness trend: at 480 mm/min scanning speed, wear reduction can be expected, with the wear volume decreasing by 58.60% and the friction coefficient reducing by 42.1% relative to 120 mm/min. Full article

Titanium and its alloys are widely used in orthopedics because of their excellent mechanical properties and biocompatibility; however, their bioinert surface results in sluggish osseointegration and renders implants susceptible to bacterial infection. This study innovatively constructed a “CHP-Ti-MAO” composite coating, which aims to simultaneously improve early osseointegration and antibacterial performance. CHP micron coatings coated with hydroxyapatite (HA) and curcumin (Cur) at different PLGA concentrations (50%, 100%, and 150%) were deposited on the basis of calcium–phosphorus ceramic coatings prepared by micro-arc oxidation (MAO) following the emulsification-solvent volatilization method. It was found that increasing the concentration of PLGA can increase the particle size of the coating, enhance the hydrophilicity, and significantly improve the sustained release performance of the drug. Among them, the 100% PLGA concentration group performed the best: the drug-release half-life reached 75 h, and the corrosion current density was the lowest (9.5 × 10⁻⁹ A/cm²), showing the best corrosion resistance. This group of coatings has a strong and long-term antibacterial effect on Escherichia coli, with an antibacterial rate of more than 95% at 24 h and more than 99% by day 17. The hemolysis rate of all coatings was lower than 5%, indicating good biocompatibility. This study confirmed that 100% CHP-Ti-MAO composite coating successfully solved the limitations of excessive pore size and insufficient antibacterial persistence of an MAO layer and also had excellent slow-release, corrosion resistance, and high-efficiency antibacterial capabilities, which provided an important basis for the development of a new generation of multifunctional titanium-based implants. Full article

The treatment of organic waste from dyes or other industry processes is a crucial issue that requires urgent attention. Photocatalysis is a promising method for tackling this problem, with ZnO being a commonly used photocatalyst material. This study compared the degrading efficiency of ZnO particles and ZnO-Ag composites by utilizing flame and spray pyrolysis techniques. Under UV light, methylene blue (MB) was used as a model organic waste. The generated particles were characterized using Brunauer–Emmett–Teller (BET) surface area, scanning electron microscopy (SEM), X-Ray diffraction (XRD), and a UV-Vis spectrometer. The findings showed that the ZnO and ZnO-Ag obtained using both methods exhibited hexagonal Wurtzite crystal structures, and there was no significant difference in the crystal sizes produced. SEM analysis indicated that the morphology of the resulting particles differed significantly, with flame-synthesized particles being remarkably smaller in size (one-thirtieth the size following spray synthesis) and having smoother surfaces. Furthermore, the addition of Ag particles to ZnO enhanced the MB degradation efficiency by two to three times, achieving a maximum of 64% at 75 min. The BET analysis showed that the surface area of ZnO doped with Ag was larger compared to that of pristine ZnO. On the other hand, the ZnO-Ag particles produced via spray pyrolysis exhibited a total pore volume (determined through nitrogen adsorption–desorption analysis) three times larger than that of the particles produced via the flame method. The particles produced via spray pyrolysis also had better MB degradation performance compared to those synthesized using flame pyrolysis. Full article

Skin aging is commonly characterized by increased wrinkles, loss of elasticity, and hyperpigmentation, significantly affecting personal appearance and quality of life. Although botulinum toxin type A (BTX-A) has been widely applied in cosmetic anti-wrinkle treatments, its intrinsic cytotoxicity limits broader clinical applications. In this study, we developed a novel exosome-based BTX-A composite delivery system designed to synergize the anti-aging properties of exosomes with the wrinkle-reducing effects of BTX-A while reducing toxicity. Human adipose-derived mesenchymal stem cells were genetically modified via lentiviral transduction to overexpress Synaptic Vesicle Glycoprotein 2C (SV2C), the receptor of BTX-A, thereby producing SV2C-enriched functionalized exosomes (EXO^SV2C). These exosomes (2.0 × 10⁷ particles/mL) were incubated with BTX-A (3 U/mL) to generate the EXO^SV2C-BTX-A complex. In vitro, EXO^SV2C-BTX-A significantly promoted the proliferation and migration of human dermal fibroblasts and effectively alleviated D-galactose (D-gal)-induced cellular senescence and collagen type I loss. These effects were superior to those observed with either BTX-A or exosomes alone. In vivo, intradermal injection of EXO^SV2C-BTX-A for 28 days markedly suppressed D-gal-induced skin aging in 8-week-old male KM mice, as evidenced by reduced malondialdehyde levels in dermal tissue, enhanced collagen type I expression, and preserved skin structure. Notably, the composite exhibited significantly lower toxicity compared to free BTX-A. Collectively, these findings highlight EXO^SV2C-BTX-A as a promising exosome-mediated BTX-A delivery platform with enhanced anti-aging efficacy and improved biocompatibility, offering a potential therapeutic strategy for skin rejuvenation. Full article

Almond skin (AS) from industrial almond peeling is considered an agri-food waste with adequate composition to obtain composite films for food packaging due to its richness in polysaccharides, proteins, and phenolic compounds. Composite films based on amorphous polylactic acid (PLA) or partially acetylated polyvinilalcohol (PVA) were obtained by melt blending and compression moulding, incorporating different ratios of defatted AS powder (0, 5, 10, and 15 wt.%). The filler was better integrated in the polar PVA matrix, where more interactions were detected with the filler compounds, affecting glass transition and crystallization of the polymer. The AS particles provided the films with the characteristic colour of the powder and strong UV light-blocking effect, while improving the oxygen barrier capacity of both polymeric matrices (24% in PLA with 15% AS and 42% in PVA with 10% AS). The water vapour permeability increased in PLA (by 192% at 15% AS), but decreased in PVA films, especially with low AS content (by 19% with 5% particles). The filler also provided the PLA and PVA films with antioxidant properties due to its phenolic richness, improving the oxygen barrier capacity of the materials and delaying the unsaturated oil oxidation. This was reflected in the lower peroxide and conjugated dienes and trienes values of the sunflower oil packaged in single-dose bags of the different materials. The high oxygen barrier capacity of the PVA bags mainly controlled the preservation of the oil, which made the effect of the antioxidant AS powder less noticeable. Full article

The current plunger gas lift production process still relies on the traditional ‘one-to-one’ control configuration, where one controller manages a single gas well. This approach does not fulfil platform requirements for centralized, efficient, and unified coordination and management of multiple wells. To increase production, improve efficiency, and mitigate safety risks, this article offers an intelligent optimization method for a collaborative plunger gas lift in multi-objective, multi-well platforms. The method integrates mechanistic modeling and data-driven approaches to develop a collaborative model for multiple wells on the platform, accounting for inter-well pressure interference and pipeline backpressure. A particle swarm optimization algorithm is implemented to solve the model, with a composite fitness function balancing maximum daily gas production and minimum production fluctuations. A case study on the XXX Platform shows that the method enhances total gas production, reduces production fluctuations, and lowers system backpressure compared to the current operating schedule. Implemented via a localized edge computing architecture, it supports real-time scheduling, providing technical references for shale gas development. Full article