Search Results (9,234)

During braking, high-power wind turbine disc brake friction pairs experience thermo-mechanical interactions at the interface, which lead to both physical and chemical changes. The friction interface features asperities and embedded hard particles within the substrate. Wear debris from these asperities or dislodged hard particles accumulates at the interface, continuing to participate in the friction process—a phenomenon known as the “endogenous third body”. Throughout braking, the microscopic morphology and contact conditions of the interface evolve dynamically. The stress–strain distribution and vibration behaviour of the friction system, influenced by the endogenous third body, also vary with braking parameters. This study employs the W-M fractal theory to develop a finite element model of a rough friction interface containing hard-particle endogenous third bodies. The model is validated through experimental testing. Based on the performance test parameters of high-power wind turbine disc brakes, a simulation is conducted to analyse the contact friction process involving the endogenous third body at the rough interface between the brake disc and brake pad. The simulation reproduces the formation process of the endogenous third body and reveals its evolutionary stages, including “ploughing”, “gap-filling”, and “aggregation”. Additionally, the study examines changes in the internal stress–strain and vibration states of the friction system under varying braking speeds (5 m/s to 35 m/s) and braking loads (3 MPa to 6 MPa). The findings demonstrate how different braking parameters influence the friction system containing the endogenous third body. The results showed that when the braking speeds were 5 m/s, 15 m/s, 25 m/s, and 35 m/s, and the braking load was 6 MPa, the average amplitude of the brake pads was the smallest, at 0.017 mm, 0.021 mm, 0.025 mm, and 0.020 mm, respectively. This research provides valuable insights into the three-body contact friction mechanism at the micro-braking interface, the formation of composite material third bodies, and the role of wear-stage third bodies in affecting the friction interface. Full article

The effect of the process aid “OPS” on the rheological properties of hydroxyl-terminated polybutadiene propellant was investigated by formulating different components of high-solid-content slurry, and the change in slurry viscosity with shear rate, surface morphology of solid-phase particles, and contact angle of the relevant interfaces were characterized. The results showed that the polyalkene polyamine surfactant OPS could significantly reduce the apparent viscosity and enhance the rheological properties of the slurry, to up to a 30% reduction, and the effect was achieved by adjusting the interfacial properties of the aluminum powder and the binder system. With the addition of 0.1% OPS, the contact angle of the interface between the aluminum powder and the binder was obviously reduced, from 97° to 30°, and the wetting was significantly enhanced, so it was judged that the OPS was suitable for HTPB-based composite propellants. Full article

Aluminum 7075 alloys are widely utilized in aerospace, transportation, and marine industries due to their high strength and low density. However, further research is needed to understand their mechanical, thermomechanical, and vibrational behaviors when reinforced. This study focuses on the development of Al 7075 composites reinforced with zirconium silicate (ZrSiO₄), processed via sand stir casting. The mechanical properties, including tensile, compression, and impact strength, as well as thermomechanical and vibrational behaviors, were thoroughly investigated. A planetary ball mill was used to mix ZrSiO₄ with a wettability agent, and the results indicated that the addition of ZrSiO₄ with the wettability agent significantly enhanced the mechanical properties. Fourier Transform Infrared Spectroscopy (FTIR) was employed to identify the compounds formed after adding the reinforcement and wettability agent. Scanning Electron Microscope (SEM) images and Energy-dispersive X-ray (EDX) analysis revealed a uniform distribution of the particles within the matrix. The tensile, compression, and impact strengths increased by 20%, 21%, and 19%, respectively, with the addition of 8 wt% ZrSiO₄; however, strain decreased. Additionally, heat treatment further enhanced the mechanical properties of the composites. The thermomechanical properties showed improvement even at elevated temperatures, and the damping factor was enhanced with the addition of ZrSiO₄. The elemental composition of the reinforced composites was analyzed using EDX, confirming the presence of the reinforcement. This research highlights the potential of Al 7075-ZrSiO₄ composites for improved performance in various applications. Full article

This study aims to establish an equivalent parallel capacitance model for a copper/polydimethylsiloxane (Cu/PDMS) capacitive flexible pressure sensor and modulate its relative permittivity to optimize pressure sensing performance. The Cu/PDMS composite material is an ideal dielectric layer for sensors due to its high dielectric constant and tunable elasticity. By adjusting the different mixing ratios of PDMS and copper particles in micro size, the components and structure properties of the composite material can be modified, thereby affecting the electrical and mechanical performance of the sensor. We used finite element analysis (FEA) to model the sensor structure and studied the capacitance changes under various normal loading conditions to assess its sensitivity and distribution characteristics. Experimental results show that the sensor has good sensitivity and repeatability in the pressure range of 0 to 50 kPa. Additionally, we explored the effect of the addition of carbon black particles. It could be inferred that the added carbon black can enhance electrical properties due to its conductivity, which would be consequenced by the distribution optimization of Cu particles for carbon black’s low density, and it can mechanically restore some flexibility up to nearly 20%. Through these studies, our work can provide theoretical support for the design and application of flexible pressure sensors. Full article

Background/Objectives: Salt-based density gradient ultracentrifugation (SBUC) is frequently used to isolate lipoproteins for their subsequent analysis. However, the addition of salts may disrupt their molecular composition. Therefore, the aim of the present study was to assess the impact of SBUC upon the molecular composition of low-density lipoprotein (LDL) particles, compared to a validated non-salt method involving iodixanol gradient ultracentrifugation (IGUC). Methods: Whole human plasma was analysed for various lipid parameters before LDL particles were isolated using both SBUC and IGUC methods. Each fraction was then filtered to obtain low-molecular-weight compounds. The LDL molecular content of the resulting fractions from both methods was determined using untargeted liquid chromatography–mass spectrometry (LC-MS) in positive and negative modes. Results: A total of 1041 and 401 features were putatively identified using positive and negative modes, respectively. Differences were shown in the molecular composition of LDL prepared using SBUC and IGUC; in positive mode ionisation, the PLS-DA model showed reasonable fit and discriminatory power (R2 = 0.63, Q2 = 0.58, accuracy 0.88) and permutation testing was significant (p < 0.001). Conclusions: The findings reveal distinct differences in the small molecule composition of LDL prepared using the two methods, with IGUC exhibiting greater variation. In negative mode, both methods detected phospholipids, long-chain sphingolipids, and ceramides, but IGUC showed higher fold differences for some phospholipids. However, in positive mode, non-native brominated adducts were found in LDL isolated using SBUC and evidence of potential bacterial contamination was discovered in samples prepared using IGUC, both of which have the capacity to affect in vitro experiments. Full article

Saprolite ores in nickel laterite deposits are pyrometallurgically processed to produce Fe-Ni alloy and Ni matte. The key to achieving the highest recovery degrees from nickel ore in electric arc furnaces and producing top-quality ferro-nickel alloys lies in maintaining optimal carbon consumption and carefully controlling the composition of the slag. This research work focused on finding the optimal smelting procedure for extracting ferro-nickel from calcined nickel ore. Comparing experimental data to the results of thermodynamic modeling using Factsage 8.2 software was a key part of the study. The nickel smelting process, which involved a carbon consumption of 4 wt.%, resulted in ferro-nickel with an Fe/Ni ratio of 4.89 and slag with a nickel content of just 0.017%. The structure and properties of nickel slag in the MgO-SiO₂-FeO system were investigated by observing the changes in the MgO/SiO₂ ratio. This study found a significant nickel recovery degree of 95.6% within the optimal M/S ratio range of 0.65 to 0.7. When the M/S ratio exceeds 0.7, iron-rich magnesium silicates (Mg_xFe_ySiO_2+n) are generated within the slag. These compounds are released downwards due to their higher specific weight, restricting the movement of small metal particles and contributing to increased metal loss through the slag. Optimized slags could revolutionize smelting, increasing metal recovery while minimizing environmental impact. Full article

In this paper, the abrasive effects of lunar simulant regoliths (LHS-1, LMS-1) have been investigated. Sealing performance of different sealant pin materials on stainless steel has been tested by the pin-on-disc method. Pin materials included block types such as pure polytetrafluoroethylene (PTFE), composite PTFE, as well as braided PTFE and hybrid-composite braided PTFE. Tribological properties were evaluated based on measured friction, wear, surface roughness and scanning electron micrographs. Most significant differences were observed in the sealing effect of the pins between the braided and the block-type pin materials. The stainless steel/pin pairs showed significantly higher (0.4–0.5) friction coefficients for the braided pins than the block ones (0.2–0.3), while there was not a significant difference in the abrasive effect of the different lunar regoliths. Although significant wear of the steel part occurred only with the block-type pins, this disadvantage was apparent in comparison with the braided pins. The abrasive particles caused deformation and eventually complete disintegration of the braided pins. Both the coefficient of friction and the wear could be estimated by a multiple linear regression model, in which different regolith size was the dominant independent parameter for the various pins. Full article

Y₂O₃-coated MgO: Ce⁺³ particles with different precipitants were prepared by the co-precipitation method; the phase and morphology of the sample were characterized by XRD, TEM, and DTA-TG, and the apparent activation energy of the coated particles was studied by thermal analysis kinetics. The results showed that the precursors synthesized by single-phase and multi-phase precipitants were calcined at 1000 °C for 1.5 h to obtain Y₂O₃-coated MgO: Ce⁺³ particles with coating thicknesses of about 2.5 nm and 5 nm. The apparent activation energies of the precursor phase change in three stages were calculated using the Doyle–Ozawa method and the Kissinger method. The average values for single-phase samples were 95.61, 74.90, and 275.27 kJ/mol, while those for multi-phase samples were 74.90, 56.06, and 240.14 kJ/mol. The activation energies for the grain growth of the two samples were 30.56 kJ/mol and 26.27 kJ/mol. Due to the differences in activation energies at each reaction stage, the reason for the influence on the thickness of the coating layer of the two precipitants is that the smaller the activation energy, the lower the required synthesis energy. An increase in coating thickness indicates an improvement in the surface activity of the coated particles. Moreover, the luminescence intensity of the composite sample is significantly higher than that of the single-phase sample, and the luminescence performance is optimal when the Ce⁺³ ion in the composite sample is 0.3 mol%. Full article

Silver nanoparticle-coated multi-walled carbon nanotube (Ag/MWNT) composites were prepared using a chemical plating method that effectively controls the overgrowth of silver nanoparticles, ensuring uniform particle size. Functionalization of the carbon nanotube surface with numerous functional groups facilitates the binding of silver ions to multi-walled carbon nanotubes (MWNTs). This process results in Ag/MWNT composites with a uniform distribution of silver nanoparticles, prepared through reduction via the silver mirror reaction. The impact of dispersants and reducing agents on the silver coating of carbon nanotubes was studied. The results revealed the formation of negatively charged functional groups (-COOH, -OH, -C=O, and -NH2) on the nanotube surface. These groups acted as nucleation sites for the formation of silver nanoparticles. These groups acted as nucleation sites for the formation of silver nanoparticles. Simultaneously, the Ag/MWNT composites demonstrated effective dispersion within the matrix, improving the electrical conductivity of the electronic paste by 32.1% and 33.1%. This improvement was attributed to the forming of a conductive pathway within the silver-modified composite. Ag/MWNT composites within the paste system improved interfacial contact between fillers and the matrix, enhancing their potential applications in thermal interface materials. Full article

The aim of this study was to evaluate the applicability of high-protein preparations in the production of ice cream. Ice cream for the experiment was produced with the addition of the following high-protein preparations: micellar casein concentrate (CN) obtained from skimmed milk, buttermilk protein concentrate (BMP), whey protein concentrate (WPC) with 80% protein content, and skimmed milk powder (SMP) as the control sample. The ice cream mix (composition, colour, and consistency index) and the ice cream (overrun, melting rate, hardness, and sensory attributes) were analysed in this study. The addition of high-protein preparations increased the protein content of the ice cream mix, thus modifying selected properties of the mix and the produced ice cream. Mixes fortified with high-protein preparations were characterised by a higher consistency index (maximum values for WPC) and larger particle size (maximum values for CN) than those of the control sample. The whiteness index was lower in high-protein ice cream mixes than in the control sample. Depending on the type of preparation added to the ice cream mix, the resulting ice cream differed in hardness (hardness was highest in samples containing WPC, 276.54 N), overrun (lowest in samples containing WPC, 52.40%), and melting rate (lowest in samples containing BMP and highest in samples containing WPC, 0.24 g/min). High-protein preparations did not induce significant changes in ice cream palatability, except for ice cream fortified with WPC, which scored lower in the sensory analysis due to lower fluffiness, higher brittleness, and sour aroma and taste. Full article

Background/Objectives: The present study focused on the formulation and evaluation of novel topical systems containing Salvia officinalis (sage), emphasizing their antioxidant and anti-inflammatory properties. Sage, rich in carnosol, offers considerable therapeutic potential, yet its low water solubility limits its effectiveness in traditional formulations. The aim of our experimental work was to improve the solubility and thus bioavailability of the active ingredient by developing self-nano/microemulsifying drug delivery systems (SN/MEDDSs) with the help of Labrasol and Labrafil M as the nonionic surfactants, Transcutol HP as the co-surfactant, and isopropyl myristate as the oily phase. Methods: The formulations were characterized for droplet size, zeta potential, polydispersity index (PDI), encapsulation efficacy, and stability. The composition exhibiting the most favorable characteristics, with particle sizes falling within the nanoscale range, was incorporated into a cream and a gel, which were compared for their textural properties, carnosol penetration, biocompatibility and efficacy. Results: Release studies conducted using Franz diffusion cells demonstrated that the SNEDDS-based cream achieved up to 80% carnosol release, outperforming gels. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) test and enzyme-linked immunosorbent assays (ELISA) showed strong efficacy, with an in vivo carrageenan-induced rat paw edema model revealing that the SNEDDS-based cream significantly reduced inflammation. Conclusions: These findings highlight the potential of SNEDDS-enhanced topical formulations in improving therapeutic outcomes. Further research is warranted to confirm their long-term safety and efficacy. Full article

Carbon fibre-reinforced polymers (CFRPs) are a lightweight alternative solution for various applications due to their mechanical and structural properties. However, debonding at the fibre–matrix interface is an important failure mechanism in composite materials. Proposed solutions include using nano-scale reinforcements to strengthen and toughen structural composites. This study covers a comprehensive approach for evaluating occupational hazards during the sizing of 6k carbon fibres using multi-walled functionalized carbon nanotubes (MWCNTs) and few-layer graphene (FLG) at a pilot scale. Material hazard and exposure banding showed elevated risks of exposure to nanomaterials during the sizing process, while a ‘what-if’ process hazard analysis allowed for the evaluation of hazard control options against the hypothetical process failure scenarios of human error and utilities malfunctioning. On-site measurements of airborne particles highlighted that using MWCNTs or FLG as a sizing agent had negligible effects on the overall exposure potential, and higher micro-size particle concentrations were observed at the beginning of the process, while particle size distribution showcased high concentrations of particles below 50 nm. This analysis provides a thorough investigation of the risks and potential exposure to airborne hazardous substances during CF sizing while providing insights for the effective implementation of a safe-by-design strategy for designing targeted hazard control systems. Full article

Green synthesis of nanocomposites offers an eco-friendly and viable solution to overcome the limitations of conventional chemical and physical methods as it uses biological agents to act as reducing and stabilizing agents. The current study’s novelty is phyto-fabricated manganese (Mn)-doped zinc oxide (ZnO) nanocomposites using aqueous extract of H. enneaspermus by a biological method. Mn-doped ZnO nanocomposites were synthesized using manganese acetate and zinc acetate. The synthesized nanocomposites were characterized by XRD, FTIR, SEM, and EDX analysis. XRD shows the crystalline nature of nanocomposites with particle sizes of 30–40 nm, and FTIR reveals the presence of functional groups responsible for capping and stabilization. SEM analysis indicates spherical morphology with minor aggregation due to phytochemical interactions. EDX analysis of Mn-doped ZnO nanocomposites was used to verify the elemental composition, including Mn, Zn, O, and C. The anti-bacterial property of Mn-doped ZnO nanocomposites was assessed using the agar well-diffusion method against pathogens. The results of the anti-bacterial investigation proved that Mn-doped ZnO nanocomposites inhibit the growth of pathogens at different concentrations. The research concludes that the extract of H. enneaspermus acts as a capping and reducing agent in the synthesis process. The process can offer bio-compatible nanocomposites for new drug development against pathogens. Full article

Extracellular vesicles (EVs) are lipid bilayer particles released by virtually all cells, with prominent roles in both physiological and pathological processes. The size, number, and molecular composition of released EVs correlate to the cells of origin, modulated by the cell’s environment and pathologic state. The proteins, DNA, RNA, and protein cargo carried by EVs are protected by degradation, with a prominent role in targeted intercellular signaling. These properties make EVs salient targets as both carriers of biomarkers and potential therapeutic delivery vehicles. The majority of EV research has focused on blood, urine, saliva, and cerebrospinal fluid due to easy accessibility. EVs have also been identified and studied in all ocular biofluids, including the vitreous humor, the aqueous humor, and the tear film, and the study of EVs in ocular disease is a new, promising, and underexplored direction with unique challenges and considerations. This review covers recent advances in the diagnostic and therapeutic use of ocular EVs, with a focus on human applications and key preceding in vitro and in vivo animal studies. We also discuss future directions based on the study of EVs in other organ systems and disease sates. Full article

Antimicrobial polymeric coatings rely not only on their surface functionalities but also on nanoparticles (NPs). Antimicrobial coatings gain their properties from the addition of NPs into a polymeric matrix. NPs that have been used include metal-based NPs, metal oxide NPs, carbon-based nanomaterials, and organic NPs. Copper NPs and silver NPs exhibit antibacterial and antifungal properties. So, when present in coatings, they will release metal ions with the combined effect of having bacteriostatic/bactericidal properties, preventing the growth of pathogens on surfaces covered by these nano-enhanced films. In addition, metal oxide NPs such as titanium dioxide NPs (TiO₂ NPs) and zinc oxide NPs (ZnONPs) are used as NPs in antimicrobial polymeric coatings. Under UV irradiation, these NPs show photocatalytic properties that lead to the production of reactive oxygen species (ROS) when exposed to UV radiation. After various forms of nano-carbon materials were successfully developed over the past decade, they and their derivatives from graphite/nanotubes, and composite sheets have been receiving more attention because they share an extremely large surface area, excellent mechanical strength, etc. These NPs not only show the ability to cause oxidative stress but also have the ability to release antimicrobial chemicals under control, resulting in long-lasting antibacterial action. The effectiveness and life spans of the antifouling performance of a variety of polymeric materials have been improved by adding nano-sized particles to those coatings. Full article