Search Results (126)

This study explores the fabrication and characterization of hybrid aluminum matrix composites reinforced with boron carbide (B₄C) and microsilica, produced via ultrasonically assisted stir casting followed by T6 heat treatment. Pure aluminum was selected as the base matrix to evaluate the combined effects of B₄C and microsilica reinforcements. Microstructural analyses showed that ultrasonic treatment effectively dispersed nanoparticles, reduced agglomeration, and enhanced particle–matrix interfacial bonding. T6 heat treatment further refined the grain structure through Zener pinning and promoted the formation of reaction layers at particle interfaces. Mechanical testing revealed that Al/B₄C composites provided the highest strength and hardness, while Al/microsilica systems retained superior ductility. The hybrid Al/B₄C/microsilica composites demonstrated a balanced combination of yield strength (38.6 MPa), ultimate tensile strength (82.6 MPa), and elongation (35.2%), confirming a synergistic strengthening–toughening effect. These results highlight the potential of Al/B₄C/microsilica hybrid reinforcements to optimize the trade-off between strength and ductility in aluminum-based composites. Full article

In the development of functional foods with therapeutic value, nanoliposomal carriers offer a promising strategy for enhancing the stability and efficacy of bioactive compounds in dairy matrices. This study evaluated the sensory acceptance and physicochemical stability of yogurt enriched with anthocyanin-loaded nanoliposomes during 21 days of refrigerated storage, assessing the impact of nanoencapsulation on compound preservation and quality. Nanoliposomes were synthesized using ultrasonic film dispersion and characterized for antioxidant and erythroprotective activities. Antioxidant capacity was assessed through DPPH, ABTS, and FRAP assays, while erythroprotective effects were evaluated via oxidative hemolysis using human erythrocytes of different ABO/RhD phenotypes. These were incorporated into artisanal yogurt, followed by physicochemical, microbiological, rheological, and sensory analyses. Anthocyanins showed strong antioxidant capacity, especially in ABTS (93.24%), DPPH (21.34%), and FRAP (1023.24 µM TE/g D.W.), reflecting their radical scavenging and reducing power. They also exhibited high erythroprotective activity, with greater antihemolytic effects in O RhD− blood and enhanced photoprotection against UVA in O RhD+ blood. Yogurt enriched with nanoliposomes showed improved color stability, reduced syneresis, and favorable rheological and sensory characteristics. These findings support nanoliposomes as molecular delivery systems in functional dairy matrices with potential nutraceutical applications targeting oxidative stress. Further work should explore molecular mechanisms and validate health-promoting effects. Full article

Essential oils play important roles in the modern food industry as additives and spices. At the same time, most essential oils have broad-spectrum bacteriostatic properties and can be used as natural antimicrobial materials. However, the application of essential oils is limited due to their strong volatility and insolubility in aqueous substrates. In this study, we used ultrasonic emulsification, carboxymethyl chitosan, and Tween 80 to formulate tea tree essential oil (TTO) nanoemulsions with high stability. With a minimum diameter of about 51 nm (PDI = 0.236 ± 0.021) post-emulsification, the TTO nanoemulsions disperse effectively in the drainage system and exhibit good stability after 14 days of storage. In addition, the bioactivity (antibacterial and antioxidant) of TTO nanoemulsions was significantly enhanced following emulsification, as evidenced by MIC and DPPH assays, indicating that nano-emulsification is beneficial to the development of various essential oils. TTO nanoemulsions can be used as a new food preservative to control the growth of bacteria and prevent the deterioration of food via oxidation. Full article

Bats are ecologically vital mammals, serving as pollinators, seed dispersers, and bioindicators of ecosystem health. Many species inhabit natural caves, which offer optimal conditions for survival but present challenges for direct ecological monitoring due to their dark, complex, and inaccessible environments. Traditional monitoring methods, such as mist-netting, are invasive and limited in scope, highlighting the need for non-intrusive alternatives. In this work, we present a portable multisensor platform designed to operate in underground habitats. The system captures multimodal data, including near-infrared (NIR) imagery, ultrasonic audio, 3D structural data, and RGB video. Focusing on NIR imagery, we evaluate the effectiveness of the YOLO object detection framework for automated bat detection and counting. Experiments were conducted using a dataset of NIR images collected in natural shelters. Three YOLO variants (v10, v11, and v12) were trained and tested on this dataset. The models achieved high detection accuracy, with YOLO v12m reaching a mean average precision (mAP) of 0.981. These results demonstrate that combining NIR imaging with deep learning enables accurate and non-invasive monitoring of bats in challenging environments. The proposed approach offers a scalable tool for ecological research and conservation, supporting population assessment and behavioral studies without disturbing bat colonies. Full article

MPs are pervasive pollutants in marine ecosystems, posing risks to aquatic organisms due to their small size and bioaccumulation potential. This study investigated the intestinal toxicity of MP particles extracted from mangrove sediments in zebrafish, comparing the effects before and after microbial degradation. Zebrafish were exposed to either undegraded MPs or microbially degraded MP extracts at concentrations of 0 (control), 2, 10, and 50 mg/L for 21 days in 10 L tanks (stocking density: 10 fish/L), with three replicate tanks per concentration. MPs were dispersed ultrasonically before addition to the water. Intestinal samples were collected on 7, 14, and 21 days for the analysis of immune response (tumor necrosis factor-alpha, TNF-α; interleukin-1 beta, IL-1β; interleukin-6, IL-6; interleukin-8, IL-8) and antioxidant activity (superoxide dismutase, SOD; catalase, CAT). Histopathological analysis revealed intestinal wall thinning, villus damage, and epithelial cell detachment in zebrafish exposed to both undegraded and degraded MP extracts; however, undegraded MPs induced more severe intestinal damage. Results indicated dynamic changes in cytokine expression: TNF-α decreased initially before increasing, while IL-1β and IL-8 first rose then declined. IL-6 peaked on day 7, dropped by day 14, and increased again on day 21. CAT expression decreased, whereas SOD increased only in the pre-degradation group. Microbial degradation reduced intestinal damage severity, with effects intensifying at higher MP exposure levels. These findings demonstrate that MPs can impair zebrafish digestive systems, but microbial degradation mitigates their toxicity. This study underscores the importance of biodegradation as a potential environmental remediation strategy and provides experimental evidence on MPs’ impact on aquatic organisms. Full article

Extensive studies have established that ultrasonic micro-jets and acoustic cavitation selectively intensify interfacial interactions at multiphase boundaries, thereby enhancing the flotation of soluble salt minerals and oxide ores. Although a growing body of evidence shows that pulp-borne nanoparticles (i.e., nanosolids, colloids, and nanoscale gas nuclei) mediate these effects, their role in the flotation of ultrafine smithsonite after collector addition has not yet been systematically examined. To fill this gap, we compared the flotation response of ultrafine smithsonite under conventional stirring (SC) and ultrasonic conditioning (UC), using sodium oleate (NaOL) as the collector, and dissected the governing mechanisms across three pillars, mineral–NaOL interaction, particle aggregation, and frothability, with particular attention paid to how nanoparticles modulate each dimension. The flotation results show that flotation performance under UC is dictated by NaOL concentration. At low NaOL levels (i.e., below 4 × 10⁻⁴ M), UC depresses both recovery and kinetics relative to SC, while at high NaOL levels, the trend reverses and UC outperforms SC. Mechanistic analysis reveals that sonication erodes mineral surfaces and generates cavitation, flooding the pulp with various nanoparticles. When NaOL is scarce, zinc-containing components and zinc-rich nanosolids sequester the collector through non-selective adsorption and precipitation, leaving smithsonite poorly hydrophobized. Consequently, particle aggregation and pulp frothability are markedly inferior to those in the SC system, so the flotation recovery and kinetics remain lower. As the NaOL concentration rises, smithsonite becomes adequately hydrophobized, and the pulp fills with hydrophobic zinc-rich nanosolids, along with cavitation-induced gas nuclei or tiny bubbles. These nanoparticles now act as bridges, accelerating the aggregation of ultrafine smithsonite once sonication stops and agitation begins, while simultaneously improving frothability. Although the strong dispersive action of ultrasound still suppresses initial flotation kinetics, cumulative recovery ultimately surpasses that of SC. The findings delineate a nanoparticle-regulated flotation paradigm and establish a critical NaOL concentration window for effective UC in ultrafine smithsonite flotation. This framework is readily transferable to the beneficiation of other ultrafine, soluble oxidized minerals (rhodochrosite, dolomite, etc.). Full article

Oral delivery of hydrophobic compounds remains challenging due to their poor aqueous solubility and the potential toxicity associated with conventional surfactant-based emulsions. To address these issues, we present a surfactant-free encapsulation strategy using electrosprayed alginate hydrogel beads for the stable and controlled delivery of hydrophobic oils. Hydrophobic compounds were dispersed in high-viscosity alginate solutions without surfactants via ultrasonication, forming kinetically stable oil-in-water dispersions. These mixtures were electrosprayed into calcium chloride baths, yielding monodisperse hydrogel beads. Higher alginate concentrations improved droplet sphericity and suppressed phase separation by enhancing matrix viscosity. The resulting beads exhibited stimuli-responsive degradation and controlled release behavior in response to physiological ionic strength. Dense alginate networks delayed ion exchange and prolonged structural integrity, while elevated external ionic conditions triggered rapid disintegration and immediate payload release. This simple and scalable system offers a biocompatible platform for the oral delivery of lipophilic active compounds without the need for surfactants or complex fabrication steps. Full article

We propose a single-phase chiral elastic metamaterial capable of simultaneously exhibiting negative effective mass density and negative bulk modulus in the ultrasonic frequency range. The unit cell consists of a regular hexagonal frame connected to a central circular mass through six obliquely oriented, slender aluminum beams. The design avoids the manufacturing complexity of multi-phase systems by relying solely on geometric topology and chirality to induce dipolar and rotational resonances. Dispersion analysis and effective parameter retrieval confirm a double-negative frequency region from 30.9 kHz to 34 kHz. Finite element simulations further demonstrate negative refraction behavior when the metamaterial is immersed in water and subjected to 32 kHz and 32.7 kHz incident plane wave. Equifrequency curves (EFCs) analysis shows excellent agreement with simulated refraction angles, validating the material’s double-negative performance. This study provides a robust, manufacturable platform for elastic wave manipulation using a single-phase metallic metamaterial design. Full article

Al-based nanocomposite energetic materials have broad application prospects in explosives and propellants, owing to their excellent energy release efficiency. However, their insufficient reliability, poor stability, and difficulty of formation limit their practical application. This study employed self-assembly using a hydrophilic polymer polyvinylpyrrolidone (PVP) together with nano-aluminum powder (Al), copper oxide (CuO), and ammonium perchlorate (AP) to obtain high-strength and high-activity composite micrometer-sized microspheres. The influence of PVP concentration on the mechanical behavior of Al/AP composite microspheres was systematically investigated, and Al was replaced with ultrasonically dispersed Al/CuO to explore the mechanism of action of PVP in the system and the catalytic behavior of CuO. PVP significantly enhanced the interfacial bonding strength. The Al/AP/5%PVP microspheres achieved a strength of 8.4 MPa under 40% compressive strain, representing a 365% increase relative to Al/AP. The Al/CuO/AP/5%PVP microspheres achieved a strength of 10.2 MPa, representing a 309% increase relative to Al/CuO. The mechanical properties of the composite microspheres were improved by more than threefold, and their thermal reactivities were also higher. This study provides a new method for the controlled preparation of high-strength, high-activity, micrometer-sized energetic microspheres. These materials are expected to be applied in composite solid propellants to enhance their combustion efficiency. Full article

Friction leads to substantial energy losses and wear in mechanical systems. This study explores the tribological potential of the high-temperature superconductor precursor Y₂BaCuO₅ (Y211), synthesized via chemical co-precipitation, as a novel additive to PAO6 base oil. A 0.3 wt.% Y211/PAO6 lubricant (CD) was formulated using ultrasonic dispersion. Tribological performance was evaluated using a custom end-face tribometer (steel-on-iron) under varying loads (100–500 N) and speeds (300–500 rpm), comparing CD to neat PAO6. The results indicate that the Y211 additive consistently reduced the coefficient of friction (COF) relative to neat PAO6, maintaining a stable value around ~0.1. However, its effectiveness was strongly load-dependent: a significant friction reduction was observed at 100 N, while the benefit diminished at higher loads (>200 N), with the COF peaking around 200 N. Rotational speed exerted minimal influence. Compared with neat PAO6, the inclusion of 0.3 wt.% Y211 resulted in a reduction in the coefficient of friction by approximately 50% under low-load conditions (100 N), with COF values decreasing from 0.1 to 0.045. Wear depth measurements also revealed a reduction of over 30%, supporting the additive’s anti-wear efficacy. Y211 demonstrates potential as a friction-reducing additive, particularly under low loads, but its high-load performance limitations warrant further optimization and mechanistic studies. This highlights a novel tribological application for Y211. The objective of this study is to evaluate the tribological effectiveness of Y₂BaCuO₅ (Y211) as a lubricant additive, investigate its load-dependent friction behavior, and explore its feasibility as a multifunctional additive leveraging its superconductive precursor structure. Full article

This study investigates the effect of boron carbide (B₄C) ceramic reinforcement on the microstructural, mechanical, electrical, and electrochemical properties of CoCrMo, Ti, and 17-4 PH alloys produced via powder metallurgy for potential biomedical applications. A systematic experimental design was employed, incorporating varying B₄C contents into each matrix through mechanical alloying, cold pressing, and vacuum sintering. The microstructural integrity and dispersion of B₄C were examined using scanning electron microscopy. The performance of the materials was evaluated using several methods, including Vickers hardness, pin-on-disk wear testing, ultrasonic elastic modulus measurements, electrical conductivity, and electrochemical assessments (potentiodynamic polarization and EIS). This study’s findings demonstrated that B₄C significantly enhanced the hardness and wear resistance of all alloys, especially Ti- and CoCrMo-based systems. However, an inverse correlation was observed between B₄C content and corrosion resistance, especially in 17-4 PH matrices. Ti-5B₄C was identified as the most balanced composition, exhibiting high wear resistance, low corrosion rate and elastic modulus values approaching those of human bone. Weibull analysis validated the consistency and reliability of key performance metrics. The results show that adding B₄C can change the properties of biomedical alloys, offering engineering advantages for B₄C-reinforced biomedical implants. Ti-B₄C composites exhibit considerable potential for application in advanced implant technologies. Full article

This study examines the mechanical and microstructural properties of graphene-reinforced AA2219 composites developed for hydrogen storage tank inner liner applications. A novel processing route combining high-energy ball milling, ultrasonic-assisted stir casting, and squeeze casting was used to achieve homogeneous dispersion of 0.5 wt.% graphene nanoplatelets and minimise agglomeration. The composites were subjected to T6 and T8 ageing treatments to optimize their properties. Microstructural analysis revealed refined grains, uniform Al₂Cu precipitate distribution, and stable graphene retention. Mechanical testing showed that the as-cast composite exhibited a UTS of 308.6 MPa with 13.68% elongation. After T6 treatment, the UTS increased to 353.6 MPa with an elongation of 11.24%. T8 treatment further improved the UTS to 371.5 MPa, with an elongation of 8.54%. Hardness improved by 46%, from 89.6 HV (as-cast) to 131.3 HV (T8). Fractography analysis indicated a shift from brittle to ductile fracture modes after heat treatment. The purpose of this work is to develop lightweight, high-strength composites for hydrogen storage applications. The novelty of this study lies in the integrated processing approach, which ensures uniform graphene dispersion and superior mechanical performance. The results demonstrate the suitability of these composites for advanced aerospace propulsion systems. Full article

Broad lateral size and thickness distributions impede the application of hexagonal boron nitride nanosheets (BNNSs) as friction modifiers in base oil, although they possess remarkable potential for lubrication performance promotion. In this work, a cascade centrifugation-assisted liquid-phase exfoliation approach was presented to prepare BNNSs from hexagonal boron nitride (h-BN) efficiently and scalably. Subsequently, they were ultrasonically dispersed into gas-to-liquid (GTL) base oil, and their lubrication performance promotion was evaluated by a four-ball tribotester. Tribological tests demonstrated that BNNS possesses excellent friction-reducing and anti-wear properties in GTL. Furthermore, the findings indicate that at a BNNS content of 0.8 wt.%, the system displayed the lowest COF and WSD. Particularly, with an addition of 0.8 wt.% BNNS into GTL, the AFC and WSD are reduced significantly by 40.1% and 35.4% compared to pure base oil, respectively, and the surface roughness, wear depth, and wear volume were effectively reduced by 91.0%, 68.5%, and 76.8% compared to GTL base oil, respectively. Raman, SEM-EDS, and XPS results proved that the outstanding friction-reducing and anti-wear properties of BNNS can mainly be ascribed to the presence of physical adsorption film and tribo-chemical film, which were composed of FeOOH, FeO, Fe₃O₄, and B₂O₃. Full article

This study elucidates the photocatalytic NOx abatement efficacy of eco-efficient mortars incorporating construction waste-derived aggregates functionalized with nano-TiO₂. The research findings demonstrate a positive correlation between NOx abatement efficiency and nano-TiO₂ substitution ratio, with recycled glass sand (RG)-based panels exhibiting superior performance compared to standard sand and recycled clay brick sand (RCBS)-based counterparts. The employment of ultrasonic dispersion as a nano-TiO₂ incorporation method yields enhanced abatement efficiency relative to direct mixing, attributable to improved photocatalyst dispersion and surface area accessibility. The loading capacity of nano-TiO₂ on recycled aggregates is observed to be positively influenced by the concentration of nano-TiO₂ solution, with recycled clay brick sand demonstrating the highest loading capacity. RG-RCBS panels are shown to exhibit higher NOx abatement efficiency than standard sand (SS)-RCBS panels, with an optimal substitution ratio of 40% glass sand identified for maximizing abatement efficacy in RG-RCBS systems. A decline in NOx abatement efficiency is observed with increasing NOx flow rate and concentration, attributable to reduced pollutant residence time and excess pollutant load exceeding the panels’ processing capacity. Prolonged curing time also results in diminished abatement efficiency, due to microstructural alterations within the mortar matrix and the accumulation of photocatalytic reaction byproducts. Collectively, these findings underscore the potential of recycled aggregate-based mortars, in conjunction with nano-TiO₂, as a viable eco-efficient strategy for NOx abatement, highlighting the critical influence of material selection, photocatalyst loading, and operational parameters on system performance. Full article

Cement is widely used as the primary binder in concrete; however, growing environmental concerns and the rapid expansion of the construction industry have highlighted the need for more sustainable alternatives. Geopolymers have emerged as promising eco-friendly binders due to their lower carbon footprint and potential to utilize industrial byproducts. Geopolymer mortar, like other cementitious substances, exhibits brittleness and tensile weakness. Basalt fibers serve as fracture-bridging reinforcements, enhancing flexural and tensile strength by redistributing loads and postponing crack growth. Basalt fibers enhance the energy absorption capacity of the mortar, rendering it less susceptible to abrupt collapse. Basalt fibers have thermal stability up to about 800–1000 °C, rendering them appropriate for geopolymer mortars designed for fire-resistant or high-temperature applications. They assist in preserving structural integrity during heat exposure. Fibers mitigate early-age microcracks resulting from shrinkage, drying, or heat gradients. This results in a more compact and resilient microstructure. Using basalt fibers improves surface abrasion and impact resistance, which is advantageous for industrial flooring or infrastructure applications. Basalt fibers originate from natural volcanic rock, are non-toxic, and possess a minimal ecological imprint, consistent with the sustainability objectives of geopolymer applications. This study investigates the mechanical and thermal performance of a geopolymer mortar composed of metakaolin and red mud as binders, with basalt powder and limestone powder replacing traditional sand. The primary objective was to evaluate the effect of basalt fiber incorporation at varying contents (0.4%, 0.8%, and 1.2% by weight) on the durability and strength of the mortar. Eight different mortar mixes were activated using sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) solutions. Mechanical properties, including compressive strength, flexural strength, and ultrasonic pulse velocity (UPV), were tested 7 and 28 days before and after exposure to elevated temperatures (200, 400, 600, and 800 °C). The results indicated that basalt fiber significantly enhanced the performance of the geopolymer mortar, particularly at a content of 1.2%. Specimens with 1.2% fiber showed up to 20% improvement in compressive strength and 40% in flexural strength after thermal exposure, attributed to the fiber’s role in microcrack bridging and structural densification. Subsequent research should concentrate on refining fiber type, dose, and dispersion techniques to improve mechanical performance and durability. Examinations of microstructural behavior, long-term durability under environmental settings, and performance following high-temperature exposure are crucial. Furthermore, investigations into hybrid fiber systems, extensive structural applications, and life-cycle evaluations will inform the practical and sustainable implementation in the buildings. Full article