Search Results (199)

Terrain-aided navigation (TAN) enables autonomous positioning through fusing prior terrain databases with real-time sensor measurements in GNSS-denied environments. Typical factors, including wide beam width and terrain elevation variations, introduce inaccuracies in elevation measurements, degrading the performance of classical elevation-based TAN methods. The SAR altimeter operates in nadir-looking mode to acquire range–Doppler projection images with inherent cross-track ambiguity for positioning based on image information, yet its accuracy is limited by single-feature and fixed-grid approaches. In this paper, we introduce an adaptive positioning framework for the SAR altimeter that combines XGBoost-based multi-feature fusion with Bayesian particle filtering. First, a fast DDM template generation algorithm is employed to improve computational efficiency. Then, an ensemble learning framework integrating complementary similarity features is introduced to achieve robust single-frame matching. Additionally, a Bayesian filtering-based dynamic grid construction method is developed to concentrate particles in high-probability regions, eliminating boundary truncation errors inherent to fixed approaches. The proposed method’s primary advantage is the reliable three-dimensional localization under extreme radar configurations, such as wide beam width and high-altitude maneuvering platforms. Experimental results based on both simulated and real data validate the method, demonstrating superior positioning performance under wide-beam conditions. Full article

Conductive hydrogel strain sensors using poly(3,4-ethylenedioxythiophene) (PEDOT) as fillers are rapidly advancing and are emerging as candidates for monitoring devices such as wearable electronic skin. However, due to limitations such as low elongation and high hysteresis, it is difficult to fully leverage its promising sensor properties in practical applications. In this study, we synthesized flake-like PEDOT particles (FP particles) and used Polyacrylamide (PAM) as the hydrogel matrix to fabricate a conductive hydrogel strain sensor. These particles were obtained by grinding PEDOT particles prepared via a template-free method. After swelling with ethylene glycol (EG) and assembly with polyvinyl alcohol (PVA), the FP particles become porous and contain many hydroxyl groups. This design enables the adsorption of acrylamide (AM) monomers within FP particles, facilitating the in situ polymerization of PAM onto the PEDOT/PVA chains, thereby yielding a dual-network structure with strong entanglements. This gives the sensor high elongation and very low hysteresis. In addition, it offers favorable sensor performance, including high sensitivity, high repeatability, and reliability. This strain sensor can be used in wearable electronic skin applications for facial monitoring and motion detection. Full article

(1) Background: Cerium silicate (CeSi) nanoparticles (NPs) have potential as a restorative filler particle with multifunctional properties to improve longevity. To increase the biological activity, these nanoparticles can be fabricated with ultrasmall pores (mesoporous) (MPCeSi-NP) that can be loaded with a polyphosphate inhibitor, such as gallein. (2) Methods: MPCeSi-NPs were custom-synthesized with a microemulsion method, using cetyltrimethylammonium bromide (CTAB) as a template for self-assembly. Biocompatibility with oral keratinocytes/fibroblasts was tested, with the addition of examining the biomineralization potential with human bone-marrow-derived mesenchymal stromal cells (BM-MSCs). MPCeSi-NP, loaded with gallein, was tested against Rothia dentocariosa (Rd). MPCeSi-NP was added to a resin matrix of triethylene glycol dimethacrylate (TEGDMA) and Bisphenol A-glycidyl methacrylate (BisGMA) with subsequent mechanical properties evaluation. (3) Results: MPCeSi-NPs had high biocompatibility with oral keratinocytes and fibroblasts, especially at concentrations below 300 µg/mL. MPCeSi-NPs induced the biomineralization of BM-MSCs. Higher cerium levels increased mineralization. MPCeSi-NP had weak antimicrobial activity against Rd. At 1% wt, MPCeSi-NPs did not reduce the polymerization potential and mechanical properties of a TEGDMA:BisGMA polymer material, with controlled release of gallein in a simulated degradation model. (4) Conclusions: MPCeSi-NPs are highly biocompatible and bioinductive and have the potential to improve the biological response of current restorative materials. Full article

Bowl-shaped gold nanoparticles (BAuNPs) are of significant interest due to their tunable localized surface plasmon resonance (LSPR) properties. This report presents a new synthesis method that uses hemispherical hydrogen nanobubbles on planar, non-conducting surfaces as templates for gold shell deposition. Initial synthesis under stagnant conditions yielded non-uniform sub-micron particles, attributed to localized hydrogen concentration gradients. The cyclonic flow was introduced aiming to reduce these gradients, although simultaneously inducing significant particle aggregation, obscuring the open structure. To overcome these challenges, an electrochemical microfluidic system was implemented to create a laminar flow environment. This configuration optimizes ion distribution and introduces shear forces that promote particle detachment, successfully limiting particle dimensions to below 200 nm, and preventing the accumulation. Systematic optimization identified optimal parameters: an ideal channel length of 7.5 mm, an applied potential of −0.6 V, and a flow rate of 0.028 µL s⁻¹. These parameters that strike a balance between nanobubble growth and gold deposition kinetics can produce highly uniform BAuNPs with a well-defined open structure and thin solid gold shells, with an outer diameter of 105.3 ± 12.1 nm and a core diameter of 80.1 ± 11.9 nm. These structural parameters successfully shift the plasmonic resonance to 760 nm, which responds perfectly with the first biological window for potential in vivo biomedical applications. Full article

Superhydrophobic surfaces are typically achieved through the synergistic integration of appropriate nanostructures and low-surface-energy chemical compositions. This study presents a novel and facile method for constructing a superhydrophobic hierarchical structure directly on a pristine selective laser melting (SLM) titanium surface. The intrinsic partially melted Ti particles, which are inherent to the SLM fabrication process, were strategically utilized as a natural microscale template for the in situ growth of TiO₂ nanotubes via electrochemical anodization. Three distinct micro/nano-topographies were successfully fabricated, integrating the spherical microparticles with either conventional TiO₂ nanotube arrays or separated nanotube arrays. The results demonstrate that the resulting superhydrophobic behavior can be effectively regulated by two key factors: the liquid–solid contact mode at the microscale and the strength of capillary action within the nanostructures. Notably, these characteristics can be tailored by controlling the nanotube diameter and intertubular spacing. These findings contribute to a deeper understanding of the role of micro–nano hierarchical structures in engineering superhydrophobic surfaces, thereby opening new avenues for advanced applications. Full article

This study investigated the mechanism by which different fractions of chickpea protein influenced the formation of oleogels. Total chickpea protein (CPP, 0.5 wt%), chickpea albumin (ALB, 0.5 wt%), globulin (GLO, 0.5 wt%), and glutelin (GLU, 0.5 wt%) were separately used as oleogelators by combining with xanthan gum (XG, 0.5 wt%) at pH 7 to construct soybean oil-based oleogels via the emulsion-templated method. Particle size measurement revealed that the GLU-XG (526 nm) exhibited the smallest particle size compared to CPP-XG (605 nm), ALB-XG (642 nm), and GLO-XG (819 nm). The four complexes exhibited increasing surface hydrophobicity and conformational flexibility (as revealed by fluorescence spectroscopy) in the order of GLO-XG < ALB-XG < CPP-XG < GLU-XG. Compared with other complexes, the higher surface hydrophobicity, smaller particle size, and more flexible structure of GLU-XG conferred a superior surface activity. Consequently, the fabricated emulsion demonstrated a smaller droplet size (13.91 μm) and enhanced centrifugal stability (94.64%). The confocal laser scanning microscope images confirmed that the oleogel based on GLU-XG exhibited the most uniform and densest network, leading to the highest oil-binding capacity (98.7%) and storage/loss modulus, followed by those based on CPP-XG (97.2%), ALB-XG (95.6%), and GLO-XG (93.9%). This research provides a theoretical basis for using chickpea protein in oleogel formulations and enhances understanding of the structural and interfacial properties of these protein fractions. Full article

Cementitious materials prepared by the ice-templating method appear to have difficulty simultaneously possessing good mechanical properties and an oriented microstructure with microchannels. Surface micro-ceramicization of TiB₂ and the decomposed products of cement hydrates at high temperatures can be regarded as in situ solid–solid reactions involving oxygen, thereby enhancing mechanical properties. This study investigates the mechanical property changes in cement paste with different water-to-cement ratios containing 25% TiB₂ micron powder before and after high-temperature treatment. Cementitious samples are prepared using both freeze-casting (F-CAST) and regular casting (R-CAST) methods with and without the heating post-treatment. The average compressive strength of samples with a W/C of 0.65 prepared by the freeze-casting method at −60 °C with a heating post-treatment is much larger than that of samples prepared by the regular casting method with and without the same heating process. The freeze-casting process for preparing cementitious composites with TiB₂ not only reorders the distribution of water molecules but also redistributes the concentrations of the TiB₂ particles and the main hydrates in the frozen samples. Due to the concentration increase near ice crystal channels within the samples, led by the freeze concentration effect, the new products are formed and cover the channel surfaces after high-temperature treatment. This enhances both the overall and internal properties of the cement-based TiB₂ composite material. The variation in TiB₂ content within the specimens is of paramount importance. Full article

As the core abrasive in chemical mechanical polishing (CMP) processes, the morphology, size uniformity, and chemical reactivity of CeO₂ nanoparticles (NPs) are crucial factors determining the surface precision and yield of devices. In this work, a KNO₃–LiNO₃ eutectic molten salt was used as the reaction medium. By systematically adjusting key processing parameters (such as the type of cerium source, the species and dosage of surfactants, and calcination conditions), the regulatory effects of these factors on particle growth mechanisms were clarified. This adjustment enabled the controlled synthesis of spherical CeO₂ NPs with customized morphology, particle size, and surface defect states. The multi-stage reaction process of the precursor during calcination was identified by applying thermal analysis techniques, including TG-DSC and TG-FTIR. This process includes dehydration, ion exchange, and thermal decomposition. Microstructural analysis shows that the type and dosage of the cerium source and template agent significantly affect the uniformity of particle size and spherical morphology. Moreover, by using an optimized process with a heating rate of 6 °C/min and maintaining at 400 °C for 3 h, spherical CeO₂ NPs with an average particle size of 60 nm, uniform size distribution, and high sphericity were successfully synthesized via a single-step calcination process. Based on these findings, a further proposal was put forward regarding a crystal growth mechanism mediated by micelle-directed assembly and oriented attachment. This method only requires a single calcination step, has mild reaction conditions, and involves a simple process without the need for specialized equipment—features that show great potential for scalable production. It provides both a theoretical basis and experimental support for the controlled preparation of high-performance CeO₂ abrasives. Full article

This study presents a wide-linear-range flexible pressure sensor based on a gradient non-uniform porous structure. Through co-optimization of material composition and structural parameters, the sensor integrates high sensitivity, a broad linear response range, and excellent stability. The sensing layer is fabricated using a PVC/CNT composite slurry, with interdigital silver electrodes screen-printed on a PET substrate. A porous architecture is constructed via solution blending and a template method. Innovatively, orthogonal experiments were employed to optimize the conductive filler concentration and porosity. A mixed sugar template comprising particles of 50–75 μm and 125–150 μm was introduced to form a gradient non-uniform porous structure, effectively expanding the linear response range. Experimental results demonstrate that the sensor exhibits outstanding linearity (R² > 0.99) and high sensitivity (5.57 kPa⁻¹) over a broad pressure range of 0–120 kPa. It also shows a dynamic response speed of 50 ms, cyclic stability exceeding 500 cycles, and signal fluctuation of less than 5%. Scanning electron microscopy (SEM) analysis reveals the synergistic mechanism of the non-uniform pores, confirming the effectiveness of this design in reconciling the trade-off between sensitivity and linear range. This study offers new insights into the performance optimization of flexible pressure sensors and demonstrates significant potential for applications in health monitoring and electronic skin (E-skin). Full article

As a step towards the substitution of saturated fats with camellia oil in foods, a camellia oil-based oleogel was prepared using a walnut protein isolate–chitosan (WPI-CS) composite via an emulsion template method. The preparation process, structural characteristics, and stability of the oleogel were systematically analyzed. Our findings showed that varying the ratio of WPI-CS to camellia oil (CO) effectively regulated the emulsion particle size, zeta potential, and viscosity, thereby subsequently influencing the oil-holding capacity (OHC), rheological properties, and thermal stability of the oleogel. When the WPI-CS:CO ratio was 13:7, the oleogel exhibited superior performance, including relatively high OHC, improved rheological properties, and excellent thermal stability. In addition, the OHC of the oleogel varied significantly with temperature, and high oxidative stability was observed at WPI-CS ratios such as 13:7–10:10. Application tests in cake formulations demonstrated that the oleogel has potential as a partial butter replacement. This study provides a theoretical basis for the construction of WPI-based oleogels and offers new insights for the development of healthy fat substitutes. Full article

Deep eutectic solvents (DES) have emerged as a versatile and sustainable medium for the green synthesis of nanomaterials, offering a viable alternative to conventional organic solvents and ionic liquids. Nanomaterials can be synthesised in DESs via multiple routes, including chemical reduction, solvothermal, and electrochemical methods. Among the different pathways, this review focuses on the electrochemical synthesis of nanomaterials in DESs, as it offers several advantages: low cost, scalability for large-scale production, and low-temperature processing. The size, shape, and morphology (e.g., nanoparticles, nanoflowers, nanowires) of the resulting nanostructures can be tuned by adjusting the concentration of the electroactive species, the applied potential, the current density, mechanical agitation, and the electrolyte temperature. The use of DES as an electrolytic medium represents an environmentally friendly alternative. From an electrochemical perspective, it exhibits high electrochemical stability, good solubility for a wide range of precursors, and a broad electrochemical window. Furthermore, their low surface tensions promote high nucleation rates, and their high ionic strengths induce structural effects such as templating, capping and stabilisation, that play a crucial role in controlling particle morphology, size distribution and aggregation. Despite significant progress, key challenges persist, including incomplete mechanistic understanding, limited recyclability, and difficulties in scaling up synthesis while maintaining structural precision. This review highlights recent advances in the development of metal, alloy, oxide, and carbon-based composite nanomaterials obtained by electrochemical routes from DESs, along with their applications. Full article

This study presents a channel-free, micro-well–template-assisted magnetic particle trapping method for efficient single-particle isolation without the need for microfluidic channels. Dual-surface silicon micro-well arrays were fabricated using photolithography, PE-CVD, and DRIE processes, featuring hydrophilic well interiors and hydrophobic outer surfaces to enhance trapping performance. The proposed method combines magnet-assisted sedimentation with rotational sweeping of a glass slide placed above the micro-well array, enabling rapid and uniform particle confinement within a 250 × 250 well array. Experimental results showed that the trapping efficiency increased with the well width and depth, achieving over 93.8% within three trapping cycles for optimized structures. High single-particle occupancy was obtained for wells of comparable size to the particle diameter, while deeper wells enabled stable trapping with minimal loss. The entire trapping process was completed within five minutes per cycle, demonstrating a rapid, simple, and scalable approach applicable to digital immunoassay systems for ultrasensitive biomolecule detection. Full article

Porous Ti-6Al-4V foams are excellent materials due to their low density, high specific strength, and excellent biocompatibility. This study investigates the fabrication of open-cell Ti-6Al-4V foams using the replica impregnation method with polyurethane templates of varying pore sizes (20, 25, and 30 ppi) and sintering temperatures (1170 °C, 1200 °C, 1250 °C, and 1280 °C). The effects of these parameters on microstructural evolution, phase composition, and mechanical properties were examined. Microstructural analysis showed that optimum densification occurred at 1250 °C. However, at 1280 °C, excessive grain growth and pore coarsening were observed. XRD, SEM, and EDS analyses confirmed that α-Ti was the matrix phase, while titanium carbide formed in situ as a result of the carbon residues released from the decomposed polyurethane template. With the development of the TiC phase and enhanced interparticle bonding due to sintering, the compressive strength progressively increased up to 1250 °C. At 1280 °C, strength decreased due to excessive TiC growth, causing brittleness and pore coarsening, reducing structural integrity. Maximum compressive strength of 40.2 MPa and elastic modulus of 858.9 MPa were achieved at 1250 °C with balanced TiC dispersion and pore structure. Max density of 1.234 g/cm³ was obtained at 1250 °C. Gibson-Ashby analysis and the fracture surfaces confirmed the brittle behavior of the foams, which is attributed to the presence of TiC particles and microcracks in the structure. The study concludes that 1250 °C provides an ideal balance between densification and structural integrity, offering valuable insights for biomedical and structural applications. Full article

Tissue engineering offers a promising solution by developing scaffolds that mimic the extracellular matrix and guide cellular growth and differentiation. Recent evidence suggests that scaffolds must provide not only biocompatibility and appropriate mechanical properties, but also the structural complexity and heterogeneity characteristic of natural tissues. Particle-based scaffolds represent an emerging paradigm in regenerative medicine, wherein micro- and nanoparticles serve as primary building blocks rather than minor additives. This approach offers exceptional control over scaffold properties through precise selection and combination of particles with varying composition, size, rigidity, and surface characteristics. The presented review examines the fundamental principles, fabrication methods, and properties of particle-based scaffolds. It discusses how interparticle connectivity is achieved through techniques such as selective laser sintering, colloidal gel formation, and chemical cross-linking, while scaffold architecture is controlled via molding, templating, cryogelation, electrospinning, and 3D printing. The resulting materials exhibit tunable mechanical properties ranging from soft injectable gels to rigid load-bearing structures, with highly interconnected porosity that is essential for cell infiltration and vascularization. Importantly, particle-based scaffolds enable sophisticated pharmacological functionality through controlled delivery of growth factors, drugs, and bioactive molecules, while their modular nature facilitates the creation of spatial gradients mimicking native tissue complexity. Overall, the versatility of particle-based approaches positions them as prospective tools for tissue engineering applications spanning bone, cartilage, and soft tissue regeneration, offering solutions that integrate structural support with biological instruction and therapeutic delivery on a single platform. Full article

Easy and rapid preparations of magnetic Co- and Pd-containing mesoporous carbons (IM1, IM2 and DM) from green phenolic resins, amphiphilic templates and metallic salts via two synthetic routes are reported. Catalysts IM1 and IM2 are prepared via an indirect method involving two steps, i.e., the preparation of Co-containing mesoporous carbons with different Co contents (2.5 and 12.5%) and the further introduction of Pd (2.3%) via impregnation using a solution of a Pd salt and a process of thermal reduction. The mesoporous carbon obtained contains two distinct crystalline metallic phases, i.e., Co particles of 5.0 nm (IM1) and Pd nanoparticles of ~1.3 nm (IM1), while the increase in Co content triggers higher Co particle sizes of 23 nm and Pd particle sizes of 1.3 and 6.8 nm (IM2). Differently, the catalyst DM is prepared via direct synthesis, in one step, including all precursors and both metal salts. This results in Pd₅₀-Co₅₀ nanoalloys of 6.5 nm uniformly dispersed in the carbon matrix. The reactivity and reusability of catalysts IM1, IM2 and DM were then ascertained in organic synthesis for hydrogenations of nitroarenes and enones. It turned out that no reactions were observed in the presence of the catalyst DM due to the presence of Co in Pd₅₀-Co₅₀, which deactivates the catalytic activity of Pd. Gratifyingly, catalysts IM1 and IM2 were very efficient for mild hydrogenations of both nitroarenes and enones using only 5 mequiv. of supported Pd in EtOH at room temperature. The smaller Pd particle sizes (1.3 nm) and the high surface-to-volume area are probably responsible for the high reactivity observed. Catalysts IM1 and IM2 can be recovered by application of an external magnetic field. However, a more efficient magnetic recovery of catalyst IM2 compared to IM1 was observed due to its higher Co content. Catalyst IM2 can be successfully reused at least seven times without a loss of efficiency. Finally, almost-Pd-free products can be obtained directly after reaction without any purification step, since the Pd leaching is very low (<0.1% of the initial amount), thus decreasing waste and increasing the reaction’s efficiency. Full article