Search Results (365)

This work highlights the feasible fabrication of translucent ceramics from un-doped and Nd³⁺-doped BaLaLiWO₆ (BLLW) and BaLaNaWO₆ (BLNW) cubic tungstates using the Spark Plasma Sintering (SPS) method. Ceramics were sintered using pure-phase, homogeneous powders with submicron particle sizes, obtained via the solid-state reaction method. The present study investigated the microstructural, structural, and spectroscopic properties of both un-doped and Nd³⁺-doped sintered specimens. All the ceramic materials exhibited certain drawbacks that significantly contributed to their low transparency in both sample types. However, initial spectroscopic tests on sintered translucent ceramics doped with Nd³⁺ ions revealed promising properties, comparable to those of the powdered samples. Therefore, we believe that producing higher-quality ceramics would improve their spectroscopic properties. For that, further optimization of the manufacturing conditions is necessary. Full article

To enhance the fabrication consistency and surface quality of microlens array (MLA) molds, this study presents a high-quality and high-efficiency rotary profile-cutting (RPC) method conducted on a four-axis ultraprecision machining platform. A geometric model is established to define the relationship between tool parameters and microlens structural features, and the toolpath is optimized by refining control points to enhance machining accuracy. In addition, a novel tool-setting error characterization approach is developed, enabling submicron-level positioning of the diamond tool, with errors in the X and Y directions controlled within 1 μm. Experimental validation demonstrates the successful fabrication of a 6 × 6 square-array MLA mold with a curvature radius of 507 μm using the proposed RPC method. Subsequent replication of MLA through precision glass molding (PGM) yielded structures with a peak-to-valley (PV) value below 354 nm and surface roughness (Ra) below 11 nm. Optical performance tests confirm the high consistency and accuracy of the fabricated MLA, highlighting the potential of the proposed RPC technique for advanced optical component manufacturing. Full article

The growing demand for ‘clean label’ functional foods necessitates the development of products that are not only health-promoting but also possess high sensory quality. Fruit mousses are an excellent matrix for fortification, appealing to a wide consumer base. This study aimed to enrich a conventional apple–plum mousse with vitamin D₃ and sea buckthorn oil, employing an encapsulation strategy based on endogenous fruit pectin. Three mousse variants were produced: a control (traditional), one fortified via the encapsulation of vitamin D₃ and sea buckthorn oil in a pectin-based nanoemulsion, and one fortified via the direct addition of the bioactive compounds. The products were analysed using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), colorimetry, texture analysis, rheology, fatty acid profiling, and sensory evaluation (profiling and ranking). SEM and FTIR analyses confirmed the successful formation of spherical submicron capsules (approx. 100–300 nm) within the fortified mousse. Encapsulation resulted in significantly lower colour change (ΔE = 6.07 ± 0.03) compared to direct addition (ΔE = 11.16 ± 0.03). The fortified mousses exhibited approximately 16–20% lower hardness (0.21–0.22 N vs. 0.25 N) and threefold lower adhesiveness (0.06–0.08 N·s vs. 0.19 N·s) compared to the control. Rheological analysis indicated that fortification did not compromise the structural stability of the mousses (G′ > G″ across 0.1–10 Hz). The fatty acid profile was significantly improved in the fortified variants, with a three-fold increase in linoleic acid (C18:2 n-6 c: from 16.90% to 55–56%) and the introduction of γ-linolenic acid (C18:3 n-6: 0.38–0.39%). Sensory ranking revealed no significant differences in overall quality between the control and fortified mousses (p > 0.05). Pectin present in fruits can be effectively utilised to encapsulate vitamin D₃ and sea buckthorn oil, allowing the successful development of a functional fruit mousse with an improved nutritional profile and retained sensory quality. Encapsulation proved to be a superior fortification method, offering better protection of bioactive compounds and a lesser impact on the product’s original colour. Full article

The room-temperature and high-temperature microstructural characteristics and tensile properties of an Al-12Si-4Cu-2Ni-0.5Mg piston alloy modified with calcium (Ca; denoted as AC sample) or phosphorus (P; denoted as AP sample) under different heat treatment conditions were systematically analyzed. Under Ca modification, the second-phase network structure of the alloy was adjusted and strengthened by an Al-TCB master alloy. Eutectic silicon (Si) particles in the AC sample possessed a fibrous structure, whereas the AP sample contained elongated eutectic Si particles, and Ca modification was found to be a potential method for simultaneously enhancing the strength and plasticity of the alloy to a matching degree at high temperatures. The T6 treatment noticeably increased the density of nanoscale precipitates; however, it also disrupted the growth of the second-phase network structure. Micron and submicron C-TiB₂ and Al₄C₃ particles formed by the in-situ reaction of TCB particles acted as bridging phases within the second-phase network structure and enhanced the strength of the piston alloy. The ultimate tensile strength of the alloy at 350 °C increased from 74 to 101 MPa, representing a 36.5% enhancement. A comprehensive analysis revealed that Orowan strengthening was the main strengthening mechanism of the alloy at room temperature, whereas load transfer and network structure strengthening were the dominant strengthening mechanisms at high temperatures. Full article

The by-products of Cavia porcellus (legs and head) were valorized for collagen extraction using ultrasound-assisted extraction (UAE). Process optimization was performed through response surface methodology (central composite design) considering amplitude, cycle, and time as factors. Samples were pretreated with NaOH and butyl alcohol, followed by acetic acid extraction under controlled sonication. The quadratic models for yield and hydroxyproline showed excellent fit (high R², R²adj, and R²pred) with no significant lack of fit. The optimal conditions were identified at 100% amplitude, cycle = 1, and 27.47 min, and these were validated experimentally, yielding 28.15 ± 0.19% collagen and 4.18 ± 0.12% hydroxyproline, values that closely matched predictions. The optimal extract exhibited a hydrodynamic diameter of 599.3 nm, a ζ-potential of −61.3 mV, and a polydispersity index of 0.33, indicating a highly stable colloidal dispersion with submicron fibrils. SEM micrographs confirmed fibrillar bundles consistent with the particle size distribution, while FTIR spectra showed characteristic amide bands indicative of triple-helix preservation. These results demonstrate that UAE of guinea pig by-products produces collagen with high structural integrity and colloidal stability, highlighting its potential for food and biomaterial applications. Full article

Foam sound-absorbing materials develop a fine cellular structure during manufacturing, resulting in variations in porosity, cell size, and the proportion of naturally occurring thin membranes that obstruct skeletal openings. This membrane proportion significantly affects sound absorption. In this study, we utilized cross-sectional images obtained from a submicron resolution computer tomography (CT) scanner (nano-CT) that can capture membrane structures to theoretically assess the sound absorption of foam materials with membranes. We processed these cross-sectional images using techniques, including binarization, to extract the contours of the foam skeletons and the cross-sectional areas of the voids. By modeling the foam’s cross-section as the clearance between two planes, we were able to determine the propagation constant and characteristic impedance within this clearance. The effective density was adjusted based on measured tortuosity. The normal-incidence sound absorption coefficient (SAC), derived from the transfer matrix method, was then compared with experimental values obtained from a two-microphone impedance tube. Image processing techniques helped extract the skeleton cross-section and reduce residual noise, thereby minimizing the effect of variations in the binarization threshold on theoretical values. The accuracy of the theoretical model was enhanced by incorporating a correction factor for the skeleton surface area. Full article

This work presents a comprehensive study on the fabrication, microstructural evolution, and mechanical performance of hybrid aluminum matrix composites based on Al6060 alloy reinforced with ~2 wt.% TiB₂ and ~1 wt.% multi-walled carbon nanotubes (MWCNTs). The composites were produced via ultrasonically assisted stir casting followed by radial-shear rolling (RSR). The combined processing route enabled a uniform distribution of reinforcing phases and significant grain refinement in the aluminum matrix. SEM, EDS, XRD, and EBSD analyses revealed that TiB₂ particles acted as nucleation centers and grain boundary pinning agents, while MWCNTs provided a network structure that suppressed agglomeration of ceramic particles and enhanced interfacial load transfer. As a result, hybrid composites demonstrated a submicron-grained structure with reduced anisotropy. Mechanical testing confirmed that yield strength (YS) and ultimate tensile strength (UTS) increased by 67% and 38%, respectively, in the cast state compared to unreinforced Al6060, while after RSR processing, YS exceeded 115 MPa and UTS reached 164 MPa, with elongation preserved at 14%. Microhardness increased from 50.2 HV0.2 (base alloy) to 82.2 HV0.2 (hybrid composite after RSR). The combination of ultrasonic melt treatment and RSR thus provided a synergistic effect, enabling simultaneous strengthening and ductility retention. These findings highlight the potential of hybrid Al6060/TiB₂–MWCNT composites for structural applications requiring a balance of strength, ductility, and wear resistance. Full article

Particulate matter (PM) suspended in the air has posed significant potential threats to human health. However, current air filters designed to intercept PM are confronted with several challenges, including a complicated preparation process, monotonous protective performance, and uncomfortable wearability. Herein, a novel jet-splitting electrospinning strategy was demonstrated to simply fabricate a hierarchically structured PLA membrane with a high filtration performance, antibacterial performance, and rapid heat dissipation for effective and comfortable air filtering. Formulating a cationic antibacterial surfactant in the PLA solution to tailor the splitting of charged jets enables the simultaneous formation of nanofibers, submicron-fibers, and beads in the hierarchical filtration network by the single-jet electrospinning. Benefiting from the synergistic effect of multi-scale fibers and beads, the hierarchically structured filter exhibited an excellent filtration efficiency of 99.979% and high quality factor of 0.45 Pa⁻¹ against PM_0.3, with a remarkably low pressure drop of 18.7 Pa. Furthermore, the hierarchical structure endowed the filter with excellent stability in filtration performance, even under 20-cyclic and 480 min long-term tests, high-humidity tests with sodium chloride aerosol particles, and the 20-cycle PM_2.5 smoke tests. Simultaneously, the filter also demonstrated remarkable antibacterial performance and an excellent heat dissipation property—all achieved due to its PLA formulation and the hierarchical structure. Full article

Titanium matrix composites (TMCs) possess excellent properties, which are widely applied in various high-end fields. An ultrafine multi-scale network structure may further enhance the TMCs. Then, the application potential is widened. Here, the in situ synthesized TC4-B-Si composites were prepared by selective laser melting technology, to achieve ultrafine microstructure by inducing ultra-rapid heating/cooling process. The preparation process–structure–performance relationships were investigated. It was found that an appropriate laser energy density leads to high-density TMCs with stable molten pools and good interlayer bonding. With the decreasing energy density, the in situ generated TiB network structure is refined from the sub-micron scale to the nano-scale. The most Si atoms are supersaturated solid-dissolved in the titanium matrix. In addition, the TiB distribution becomes heterogeneous. Due to the co-effect of grain refinement and reinforcement distribution, the microhardness shows a rising and then falling trend, with decreasing energy density. With a good balance of these two factors, the maximum value of microhardness reaches 454 HV. Therefore, controlling process parameters is a feasible way to achieve multi-structures, and thus enhanced properties. This method is expected to be used on various lightweight and wear-resistant structural components. Full article

In the quest to produce high-purity alumina, bottom-up engineering via architecting the interior of ceramic with bimodal structures of alumina powders in the absence of any additives has gained considerable attention owing to the simplicity offered. The present work investigated the influence of bimodal structures containing micron (~35 μm) and submicron (~600 nm) Al₂O₃ powders on the formation of dense Al₂O₃ ceramic. To this end, ball-milling was conducted to prepare the desired sizes of powders, followed by two-step sintering in a vacuum at 1450 °C and 1650 °C with 6 h and 4 h holding times, consecutively. The bimodal structures induced the formation of Al₂O₃ ceramic with nearly full densification (>99%; ρ 3.95 g/cm³). Both the coarse and fine-grained moieties synergistically balanced the densification kinetics whilst suppressing abnormal grain growth. The uniform and homogeneous grain size minimized the plasma porosity down to <6.0%, limiting the penetration of plasma during the etching process. Full article

To solve the limitations of these models for submicron materials like electrospun nanofiber membranes, a numerical simulation was used to construct a three-dimensional model closer to the actual structure to explore the filtration resistance and efficiency of these membranes. Based on the actual polydisperse electrospun nanofiber filter, the three-dimensional structure (fiber diameter 280 nm–1300 nm, thickness 0.0150 mm–0.0240 mm, and solid volume fraction 11.3–17.7%) was reconstructed by GeoDict software. The filtration resistance was simulated with the FlowDict module (surface velocity 6.89 cm/s, 20 °C), and the filtration efficiency was calculated with the FilterDict module (2.5 μm particles, tracking 20,000). The results are compared with the experimental values, Davids empirical formula, Happel model, and Kuwabara model. The results show that the simulated values of filtration resistance are generally higher than the experimental values (deviation ≤ 20%), among which the simulation and experiment have the highest consistency, followed by the Davids formula (such as the relative error of 41.62% at 9% spinning solution concentration), and the Kuwabara model has the largest error (59.86%). The simulated value of filtration efficiency is higher than the experimental value (deviation ≤ 7%), because the model assumes that the particles adhere directly after contacting the fiber, and the actual sliding off is not considered. This study confirms that numerical simulation can efficiently predict the filtration performance of electrospun nanofiber membranes. Therefore, it provides a basis for optimizing material structure by adjusting spinning parameters and promoting the engineering application of submicron filter materials. Full article

Ag-doped ZnO is a promising photocatalyst. However, the combined influence of the Ag doping concentration and furnace temperature has not been adequately explored, hindering the optimization of ZnO/Ag materials for practical applications. In this study, ZnO/Ag materials were synthesized via ultrasonic spray pyrolysis by systematically varying both the furnace calcination temperature and the Ag doping concentration. The synthesized materials were analyzed through a range of spectroscopic methods to investigate their structural, morphological, and surface characteristics. Their photocatalytic activity was assessed by monitoring the degradation of methylene blue (MB) under ultraviolet light exposure. The findings indicate that the ZnO sample that was calcined at 400 °C exhibited the highest degradation efficiency among the undoped samples, which can be attributed to its submicron particle size, moderate crystallinity, and high surface hydroxylation. The sample with 5-wt% Ag doping achieved enhanced performance, demonstrating the best photocatalytic activity (65% MB degradation). This improvement was attributed to the synergistic effects of surface plasmon resonance and optimized interaction between the Ag nanoparticles and surface hydroxyl groups. Excessive Ag loading (10 wt%) led to reduced activity owing to potential agglomeration and recombination centers. These results highlight the critical role of both the thermal and chemical parameters in tailoring ZnO-based photocatalysts for wastewater treatment applications. Full article

Magneto-plasmonic structures have been a subject of tremendous attention of researchers in recent decades as they provide unique approaches regarding the efficient control of optical, magneto-optical, and nonlinear-optical effects. Among others, magneto-plasmonic crystals (MPCs) have become one of the most studied structures, known for their high-quality tunable resonant optical properties. Here, we present the results of experimental and numerical studies on the functional magneto-optical (MO) response of planar 1D plasmonic crystals composed of Co/Au stripes of submicron period on the surface of a 3 μm thick rare-earth garnet layer. The experimental and numerical studies confirm that the wavelength–angular spectra of such structures contain a set of tunable resonant features in their optical and magneto-optical response, associated with the excitation of (i) surface plasmon polaritons at the Co/Au grating–garnet interface, as well as (ii) waveguide (WG) modes propagating in the garnet slab. A comparison of the MO effects in the transversal and longitudinal magnetization of the plasmonic structures is presented. We show that the most efficient Fano-type MPC magneto-optical response is realized for the WG modes of the first order for the longitudinal magnetization of the structure. Further perspectives regarding the optimization of this type of plasmonic crystal are discussed. Full article

This study presents a microfluidic chip platform designed using a multiscale 3D printing strategy for fabricating microfluidic chips with integrated, high-resolution, and customizable membrane structures. By combining two-photon polymerization (2PP) for submicron membrane fabrication with liquid crystal display printing for rapid production of larger components, this approach addresses key challenges in membrane integration, including sealing reliability and the use of transparent materials. Compared to fully 2PP-based fabrication, the multiscale method achieved a 56-fold reduction in production time, reducing total fabrication time to approximately 7.2 h per chip and offering a highly efficient solution for integrating complex structures into fluidic chips. The fabricated chips demonstrated excellent mechanical integrity. Burst pressure testing showed that all samples withstood internal pressures averaging 1.27 ± 0.099 MPa, with some reaching up to 1.4 MPa. Flow testing from ~35 $\mathsf{\mu }$L/min to ~345 $\mathsf{\mu }$L/min confirmed stable operation in 75 $\mathsf{\mu }$m square channels, with no leakage and minimal flow resistance up to ~175 $\mathsf{\mu }$L/min without deviation from the predicted behavior in the 75 $\mathsf{\mu }$m. Membrane-integrated chips exhibited outlet flow asymmetries greater than 10%, indicating active fluid transfer across the membrane and highlighting flow-dependent permeability. Overall, this multiscale 3D printing approach offers a scalable and versatile solution for microfluidic device manufacturing. The method’s ability to integrate precise membrane structures enable advanced functionalities such as diffusion-driven particle sorting and molecular filtration, supporting a wide range of biomedical, environmental, and industrial lab-on-a-chip applications. Full article

A superhydrophobic surface with hierarchical micro/nano-array structures was successfully fabricated on 6061 aluminum alloy through a combination of femtosecond laser etching and anodic oxidation. Femtosecond laser etching formed a regularly arranged microscale “pit-protrusion” array on the aluminum alloy surface. After modification with a fluorosilane ethanol solution, the surface exhibited superhydrophobicity with a contact angle of 154°. Subsequently, the anodic oxidation process formed an anodic oxide film dominated by an array of aluminum oxide (Al₂O₃) nanopores at the submicron scale. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed that the nanopore structures uniformly and continuously covered the laser-ablated layer. This hierarchical structure significantly increased the surface water contact angle to 162°. Wettability analysis showed that the prepared composite coating formed an air layer accounting for 91% of the surface area. Compared with the sample only treated by femtosecond laser etching, the presence of the Al₂O₃ nanopore structure significantly enhanced the mechanical durability, superhydrophobic durability, and corrosion resistance of the superhydrophobic surface. The proposed multi-step fabrication strategy offers an innovative method for creating multifunctional, durable superhydrophobic coatings and has important implications for their large-scale industrial use. Full article