Search Results (454)

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

This study aimed to evaluate the effects of dietary nano-copper supplementation on growth performance, nutrient digestibility, antioxidant status, inflammatory response, and intestinal barrier function in weanling pigs under heat stress conditions. Forty 20-day-old weaned weanling pigs (Yorkshire × Landrace × Duroc) weighing 6.49 ± 0.08 kg were randomly divided into five treatments with eight replicates each. The pre-feeding period was 2 days, followed by a 22-day experimental period. All groups were exposed to high heat conditions at 35 ± 1 °C. The control group received a basal diet, while the low copper sulfate (LC) group received a diet with 50 mg/kg of copper sulfate, the high copper sulfate (HC) group received a diet with 150 mg/kg of copper sulfate, the low nano-copper (LNC) group received a diet with 50 mg/kg of nano-copper oxide, and the high nano-copper (HNC) group received a diet with 150 mg/kg of nano-copper oxide. Compared to the basal group, pigs supplemented with copper (either CuSO₄ or nano-CuO) exhibited significantly higher average daily gain (ADG, p < 0.048) and feed intake (ADFI, p = 0.005), with the 50 mg/kg nano-copper group showing improved nutrient digestibility (p < 0.05) and intestinal morphology. Nano-copper supplementation significantly enhanced mucosal SOD activity (p < 0.05), reduced MDA levels (p < 0.05), and downregulated pro-inflammatory cytokines such as IL-1β and IL-6 (p < 0.05). Notably, 50 mg/kg of nano-copper increased the apparent total tract digestibility (ATTD) of copper to 30.29%, significantly higher than the 16.55% observed in the 150 mg/kg CuSO₄ group (p < 0.05). Furthermore, fecal copper concentration was significantly reduced by 20.7% in the 50 mg/kg nano-copper group compared to copper sulfate (p < 0.001). In conclusion, nano-copper appears to be a promising alternative to copper sulfate for improving growth performance and reducing fecal copper concentrations in weanling pigs under heat stress conditions. Full article

Nano-titanium dioxide ceramic coatings exhibit excellent wear resistance, corrosion resistance, and self-cleaning properties, showing great potential as multifunctional protective materials. This study proposes a synergistic reinforcement strategy by encapsulating micron-sized Al₂O₃ particles with nano-TiO₂. A core-shell structured nanocomposite coating composed of 65 wt% nano-TiO₂ encapsulating 30 wt% micron-Al₂O₃ was precisely designed and fabricated via a slurry dip-coating method on Q235 steel substrates. The microstructure and surface morphology of the coatings were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Comprehensive performance evaluations including densification, adhesion strength, wear resistance, and thermal shock resistance were conducted. Optimal coating properties were achieved under the conditions of a binder-to-solvent ratio of 1:15 (g/mL), a heating rate of 2 °C/min, and a sintering temperature of 400 °C. XRD analysis confirmed the formation of multiple crystalline phases during the 400 °C curing process, including titanium pyrophosphate (TiP₂O₇), aluminum phosphate (AlPO₄), copper aluminate (Cu(AlO₂)₂), and a unique titanium phosphate phase (Ti₃(PO₄)₄) exclusive to the 2 °C/min heating rate. Adhesion strength tests revealed that the coating sintered at 2 °C/min exhibited superior interfacial bonding strength and outstanding performance in wear resistance, hardness, and thermal shock resistance. The incorporation of nano-TiO₂ into the 30 wt% Al₂O₃ matrix significantly enhanced the mechanical properties of the composite coating. Mechanistic studies indicated that the bonding between the nanocomposite coating and the metal substrate is primarily achieved through mechanical interlocking, forming a robust physical interface. These findings provide theoretical guidance for optimizing the fabrication process of metal-based ceramic coatings and expanding their engineering applications in various industries. Full article

Vegetable crops such as tomato are highly susceptible to various pathogens. Nanoparticles (NPs) are emerging as effective nano-bactericides for managing plant pathogens. Communities of rhizosphere bacteria are essential for plant physiological health and also serve as a critical factor in evaluating the environmental compatibility of NPs. We evaluated the effects of a nano-bactericide (Cu-Ag nanoparticles) and a commercial bactericide (thiodiazole–copper) on the rhizosphere microbiome of tomato. The results show that low and high doses of the two bactericides induced alterations in the bacterial community structure to differing extents. Cu-Ag nanoparticles increased the relative abundance of potentially beneficial bacteria, including Bacteroidota, Gemmatimonadota, Acidobacteriota, and Actinobacteriota. Functional prediction revealed that Cu-Ag nanoparticles may affect the metabolic pathways of tomato root rhizosphere microorganisms and regulate the lacI/galR family, which controls virulence factors and bacterial metabolism. This study provides insight into the influence of metal nanoparticles on plant rhizosphere microbiomes and may lay a foundation for the application of nano-bactericides for the environmentally friendly control of plant diseases. Full article

The lubrication performance of the cylinder liner–piston ring (CLPR) is crucial for the energy efficiency and operating reliability of marine diesel engines. To enhance the boundary lubrication of marine engine oil, a 1,3-diketone fluid HPTD (1-(4-hexylphenyl) tridecane-1,3-dione, HPTD) was introduced as an ash-free friction modifier. Besides that, octadecylamine-functionalized nanocopper particles (ODA-Cu) were also added to the marine oil to improve its anti-wear behavior. Through cylinder-on-disk friction tests, the appropriate contents of HPTD and ODA-Cu were determined, which then formed hybrid additives and modified the engine oil. The tribological performance of the modified oil was analyzed under various normal loads, reciprocating frequencies, and testing temperatures. Based on the synergy of the tribochemical reaction of HPTD and the mending effect of ODA-Cu on the sliding surface, the modified oil not only had lower sulfated ash content but also exhibited superior lubrication performance (i.e., reduced coefficient of friction by 15%, smaller wear track by 43%, and higher maximum non-seizure load by 11%) than the pristine engine oil. The results of this study would be helpful for the design of novel hybrid eco-friendly additives for marine engine oil. Full article

Printed electronics employ established printing methods to create low-cost, mechanically flexible devices including batteries, supercapacitors, sensors, antennas and RFID tags on plastic, paper and textile substrates. This review focuses on the specific contribution of screen printing to that landscape, examining how ink viscosity, mesh selection and squeegee dynamics govern film uniformity, pattern resolution and ultimately device performance. Recent progress in advanced ink systems is surveyed, highlighting carbon allotropes (graphene, carbon nano-onions, carbon nanotubes, graphite), silver and copper nanostructures, MXene and functional oxides that collectively enhance mechanical robustness, electrical conductivity and radio-frequency behavior. Parallel improvements in substrate engineering such as polyimide, PET, TPU, cellulose and elastomers demonstrate the technique’s capacity to accommodate complex geometries for wearable, medical and industrial applications while supporting environmentally responsible material choices such as water-borne binders and bio-based solvents. By mapping two decades of developments across energy-storage layers and functional electronics, the article identifies the key process elements, recurring challenges and emerging sustainable practices that will guide future optimization of screen-printing materials and protocols for high-performance, customizable and eco-friendly flexible devices. Full article

Novel dentin bonding pretreatment using copper sulfate (CuSO₄) and dipotassium hydrogen phosphate (K₂HPO₄) may create a more hydrophobic environment for dentin bonding. Thus, this study aims to investigate the impact of a CuSO₄ + K₂HPO₄ pretreatment on dentin μTBS when bonded with a universal adhesive to conventional and CAD/CAM resin composites. Eighty recently extracted human molars (n = 80) were chosen and placed in transparent acrylic blocks to expose the crowns entirely. Nano-filled resin composite and CAD/CAM resin blocks were selected. Based on the dentin pretreatment, type of resin composite, and adhesion strategy, the teeth were randomly allocated into eight equal groups (n = 10). The microtensile bond strength (μTBS) and fracture mode were determined. A three-way analysis of variance (ANOVA) was used to analyze the μTBS data, followed by Tukey’s post hoc test. The μTBS values were not significantly affected by either the resin composite type (p > 0.05) or the adhesive strategy (p > 0.05) according to the three-way ANOVA results. Conversely, significant differences were detected between no dentin pretreatment (24.20 ± 4.54 MPa) and CuSO₄ + K₂HPO₄ pretreatment (33.66 ± 5.22 MPa) using an etch-and-rinse adhesive strategy for nano-filled composites (p < 0.001). Additionally, significant differences were detected between no dentin pretreatment (24.71 ± 4.33 MPa) and CuSO₄ + K₂HPO₄ pretreatment (32.49 ± 4.92 MPa) using an etch-and-rinse adhesive strategy for CAD/CAM resin blocks (p < 0.001). Moreover, significant differences were detected between no dentin pretreatment (21.20 ± 3.40 MPa) and CuSO₄ + K₂HPO₄ pretreatment (30.31 ± 3.87 MPa) using a self-etching adhesive strategy for nano-filled composites (p < 0.001). Also, significant differences were detected between no dentin pretreatment (23.89 ± 3.89 MPa) and CuSO₄ + K₂HPO₄ pretreatment (31.22 ± 4.71 MPa) using a self-etching adhesive strategy for CAD/CAM resin blocks (p < 0.001). In conclusion, dentin μTBS was enhanced by a copper-based treatment when used with nano-filled and CAD/CAM resin blocks. Full article

Phase change materials (PCMs) are widely used in latent heat thermal energy storage systems (LHTESSs), but their low thermal conductivity limits performance. This study numerically investigates the enhancement of thermal efficiency in LHTESSs using nano-enhanced PCM (NePCM), composed of paraffin wax embedded with copper (Cu) nanoparticles. The NePCM is confined within a trapezoidal cavity, with the base serving as the heat source. Four different cavity heights were analyzed: cases 1, 2, 3, and 4 with the heights D of 24 mm, 18 mm, 15 mm, and 13.5 mm, respectively. The finite element method was employed to solve the governing equations. The influence of two hot base temperatures (333.15 K and 338.15 K) and Cu nanoparticle volume fractions ranging from 0% to 6% was examined. The results show that incorporating Cu nanoparticles at 6 vol% (volume fraction) enhanced thermal conductivity and reduced melting time by 10.71%. Increasing the base temperature to 338.15 K accelerated melting by 65.55%. Among all configurations, case 4 exhibited the best performance, reducing melting duration by 15.12% compared to case 1. Full article

In this study, an innovative internal oxidation-powder metallurgy combined process was employed to controllably generate nano-sized Cr₂O₃ reinforcing phases within the Cu matrix. The Cu/Cr₂O₃ composites were successfully fabricated using the hot-press sintering (HP) method, and a systematic comparison was made between the microstructure and mechanical properties of composites prepared by internal oxidation and external addition methods. The results show that internal oxidation primarily occurs during the sintering process rather than ball milling. Compared with external addition, the internal oxidation method effectively prevents particle aggregation and achieves a uniform distribution of Cr₂O₃ particles in the Cu matrix. When the Cr content reaches 5 wt%, the Cu-5%Cr composite exhibits optimal mechanical properties, with a yield strength of 282.7 MPa and ultimate tensile strength of 355 MPa, representing increases of 43% and 34% over pure copper, respectively, while maintaining an elongation of 12.6%. The Cr₂O₃ particles generated via internal oxidation enhance their strength through Orowan strengthening and dislocation pinning, thereby significantly improving mechanical performance without compromising plasticity. This research provides a novel process optimization approach for developing high-performance dispersion-strengthened copper matrix composites. Full article

Soft and flexible capacitive tactile sensors are vital in prosthetics, wearable health monitoring, and soft robotics applications. However, achieving accurate real-time force detection and spatial localization remains a significant challenge, especially in dynamic, non-rigid environments like prosthetic liners. This study presents a real-time force point detection and tracking system using a custom-fabricated soft elastomeric capacitive sensor array in conjunction with image processing and machine learning techniques. The system integrates Otsu’s thresholding, Connected Component Labeling, and a tailored cluster-tracking algorithm for anomaly detection, enabling real-time localization within 1 ms. A $6\times 6$ Dragon Skin-based sensor array was fabricated, embedded with copper yarn electrodes, and evaluated using a UR3e robotic arm and a Schunk force-torque sensor to generate controlled stimuli. The fabricated tactile sensor measures the applied force from 1 to 3 N. Sensor output was captured via a MUCA breakout board and Arduino Nano 33 IoT, transmitting the Ratio of Mutual Capacitance data for further analysis. A Python-based processing pipeline filters and visualizes the data with real-time clustering and adaptive thresholding. Machine learning models such as linear regression, Support Vector Machine, decision tree, and Gaussian Process Regression were evaluated to correlate force with capacitance values. Decision Tree Regression achieved the highest performance ($R^2=0.9996, RMSE=0.0446$), providing an effective correlation factor of $51.76$ for force estimation. The system offers robust performance in complex interactions and a scalable solution for soft robotics and prosthetic force mapping, supporting health monitoring, safe automation, and medical diagnostics. Full article

In this work, 1,3-diketone synthesized via the Claisen condensation method and nano-copper particles modified by the Brust–Schiffrin method were added into a commercial marine medium-speed diesel engine cylinder piston oil to evaluate their effects on boundary lubrication performance. Friction and wear tests conducted on CKS-coated piston ring and cast-iron cylinder liner samples demonstrated significant reductions in both friction and wear with the addition of 1,3-diketone and nano-copper particles. Compared to the original oil without additives, the friction force was reduced by up to 16.7%, while the wear of the piston ring and cylinder liner was decreased by up to 21.6% and 15.1% at 150 °C, respectively. A worn surface analysis indicated that the addition of 1,3-diketone and functionalized nano-copper particles influenced the depolymerization and tribo-chemical reactions of the anti-wear additive ZDDP (zinc dialkyldithiophosphate) in the original engine oil. This modification enhanced the oil’s anti-friction and anti-wear properties, offering valuable insights into the development of eco-friendly lubricants for energy-efficient systems. Full article

Introducing nano-twins into electrolytic copper foil is an effective method to enhance strength and toughness. While pulse electrodeposition enables the easier preparation of high-density nano-twin copper, large-scale industrial production mainly relies on direct current electrodeposition. Therefore, systematically studying the effects of electroplating parameters on the microstructure and mechanical properties of direct current electrodeposited copper foil is crucial. In this paper, we discuss the effects of pH value, C_CuSO4, and J_k on the microstructure and mechanical properties of electroplated copper foils at room temperature. The results show that copper foils exhibit stronger (220)_Cu preferred orientation on the M surface than on the S surface with changes in pH value, C_CuSO4, and J_k. When the pH value is 2.5, the C_CuSO4 is between 70 and 90 g/L, and the J_k is within the range of 70–90 mA/cm², the prepared copper foil has better compactness and no obvious pinhole-like defects. Particularly, the copper foil electroplated with a pH value of 2.5, a C_CuSO4 of 80 g/L, and a J_k of 80 mA/cm² consists of equiaxed and columnar grains, featuring small grain size, uniform distribution, and a dense structure, resulting in excellent mechanical properties. Full article

Zinc (Zn)- and copper (Cu)-containing welding fumes elevate inflammatory markers (CRP, TNF-α, IL-6, IL-8) in healthy individuals and welders. Zn- and Cu-containing nanoparticles are toxic to human macrophages. Therefore, ZnO exposure limits are under discussion. In this study, the effects of Zn/Cu-containing welding fume suspensions on A549 alveolar epithelial cells (exposure concentrations: 0.01/0.1/1/10/100 µg/mL) and THP-1 macrophages (additionally 0.001 µg/mL) were investigated over a period of 48 h. Effects on apoptosis, cytotoxicity, genotoxicity, superoxide dismutase (SOD) activity, and cytokine levels (IL-6, IL-8, MIP-1β/CCL4, TNF-α) were evaluated. Welding fume exposure increased SOD activity, and it increased Annexin-V binding and cytotoxicity effects starting at 10 µg/mL in A549 cells and particularly in THP-1 macrophages. A549 cells showed increased IL-6 at 10 and 100 µg/mL, and significant IL-8 release occurred at 10 µg/mL for A549 and 0.1 µg/mL for macrophages. Exposed macrophages released TNF-α at 1 µg/mL after 24 and 48 h and MIP-1β/CCL4 at 0.01 µg/mL after 6 h and at 0.001 µg/mL after 48 h. No genotoxic effects were detected. MIP-1β/CCL4 is a sensitive new biomarker for human macrophages exposed to Zn/Cu-containing welding fumes. The findings suggest that Zn/Cu particles affect lung cells already at doses below current occupational thresholds. Full article

This study demonstrates the achievement of robust Cu-Cu bonding strength through thermocompression bonding (TCB) under a formic acid (FA) atmosphere. When subjected to sintering at 300 °C for 1 min under FA, sintering joints exhibit an average shear strength of 50.9 MPa. This strength further increases to an average of 131 MPa when the sintering duration is extended to 20 min at the same temperature under FA. Molecular dynamics simulations are employed to model the sintering behavior of copper particles of various sizes and thus understand the diffusion mechanism. The analysis of mean square displacement (MSD) and radial distribution function from these simulations suggests that the presence of small particles aids in the sintering of large ones. A copper paste, formulated by mixing micron-sized copper particles with organic solvents, is utilized in a series of experiments to explore different sintering methodologies aimed at enhancing the mechanical integrity of the sintering joints while simultaneously addressing issues associated with copper particle oxidation. Innovative strategies, including redox processes, are applied to improve the shear strength of the sintering joints and to minimize the detrimental effects of oxidation on the copper particles. Results indicate that preoxidation, which was used to form a nano surface structure, and using an FA atmosphere, remarkably enhance the shear strength of the Cu-Cu joints created via TCB. The findings of this research are pivotal for the advancement of rapid Cu-Cu bonding techniques using micron-scale copper pastes and can have profound implications for the development of future electronic packaging and interconnection technologies. Full article

Superhydrophobic surfaces are critical in the marine industry because ships and underwater vehicles are constantly exposed to hydrodynamic friction and biofouling during operation, which can negatively affect their efficiency and increase operating costs. To address these challenges, this study proposes a straightforward method for fabricating stable superhydrophobic surfaces. By modifying nano-copper oxide on a microstructure substrate, a coating exhibiting exceptional hydrophobicity, designated as 100-SHB, was successfully developed. The 100-SHB has a water contact angle of about 163.0° and a sliding angle of about 2.0°, which is highly repulsive to water droplet impact. Furthermore, 100-SHB maintained its superhydrophobic properties under rigorous testing, including water puncture resistance, sandpaper abrasion, and ultrasonic damage tests. The incorporation of a lithography-based network structure further enhanced the mechanical stability of the surface, highlighting its robustness. In ship model experiments, the surface demonstrated a remarkable drag reduction rate of 64.2%. This environmentally friendly, simple, and scalable fabrication method represents a significant advancement toward practical implementation in the marine industry and holds promise for expanding applications in non-wetting-related fields. Full article