Search Results (10,276)

Background: Three-dimensional (3D) cell cultures are increasingly recognized as effective models for studying diseases and developing cell therapies. In the endocrine pancreas field, organoids/spheroids derived from human islet cells enable advances in diabetes research, drug screening, and tissue engineering. While various 3D culture methods exist, approaches such as magnetic bead-assisted aggregation remain underexplored for endocrine pancreatic cells. Additionally, the use of biological scaffolds, especially those derived from decellularized pancreatic extracellular matrix, provides a biomimetic environment that promotes adhesion, proliferation, and functionality of pancreatic cells. This study presents a protocol for magnetic bead-guided 3D culture of human islet cells within decellularized pancreatic scaffolds. Methods: Human pancreas from adult brain-dead donors was harvested for both islets’ isolation processing and decellularization to generate an acellular pancreatic bioscaffold. Primary human pancreatic islets were first grown in two-dimensional adherent cultures, then enzymatically harvested from the surface and reassembled into three-dimensional clusters using different initial cell amounts (small clusters 0.5 × 10⁴–1 × 10⁴ and larger clusters 2.5 × 10⁴–5 × 10⁴ cells) and then placed within acellular pancreatic slices of different thickness, namely 50 and 90 μm. Optic microscopic examination, scanning electron microscopy analysis, and assessment of insulin and lactate dehydrogenase (LDH) levels were used to evaluate these 3D islet-like cluster cultures. Results: We report the establishment of 3D cultures derived from primary pancreatic islet cells using a magnetic approach in a remarkable 18 h period for the complete formation of 3D clusters. The small clusters (0.5 × 10⁴–1 × 10⁴ cells) exhibited a faster attachment to the acellular matrix, with cells visibly spreading outside the cluster interacting with the bioscaffold slice, when compared to the larger clusters (2.5 × 10⁴–5 × 10⁴ cells). These cells continued to produce insulin, and no statistically significant differences in LDH levels were found under these different conditions. Conclusions: Here, we demonstrate that a magnetic bead-based protocol can be successfully applied to endocrine pancreatic cells, enabling the rapid formation of compact, viable, and functional 3D structures. Despite limitations such as higher cost and prolonged retention of magnetic particles, the approach supports size-dependent interactions with decellularized pancreatic scaffolds. These findings are valuable for researchers designing experiments tailored to specific objectives and underscore the potential of this platform for advancing diabetes research and pancreatic tissue engineering. Full article

This experimental review discusses evolutionarily approved, naturally pre-designed skeletal architectures of marine keratosan sponges in the form of 3D scaffolds, which have garnered increasing interest in the fields of structural and functional biomimetics as well as in tissue engineering. It has been demonstrated that these renewable, ready-to-use natural scaffolds can undergo further modifications through specialized treatments such as metallization and carbonization, enabling the creation of functional biomaterials while maintaining the species-specific hierarchical 3D structure. The study presented remarkable findings, including the demonstration of the unique shape-memory behavior of these scaffolds even after two months of exposure to high mechanical pressure at temperatures exceeding 100 °C. Additionally, the cytocompatibility and biological performance of natural and carbonized (1200 °C) spongin scaffolds, derived from selected bath sponges, were comparatively investigated with respect to growth and proliferation of human MG-63 osteoblastic cells. Understanding whether carbonization universally enhances osteogenic capabilities or selectively amplifies the inherent architectural advantages remains to be critical for the rational design of sponge-derived scaffolds in bone and structural tissue engineering applications. Full article

Superconducting transition-edge sensors (TESs) exhibit excellent single-photon detection performance. The quantum efficiency (QE), which quantifies the probability that an incident photon is absorbed and converted into a measurable signal, is strongly governed by the optical properties of the constituent thin films. Specifically, for typical TES device architectures where optical transmission is negligible, maximizing the QE requires the minimization of surface reflectance to ensure high photon absorptance. In this work, we systematically study how anodic oxidation modifies the optical response of superconducting titanium (Ti) thin films that are relevant for TES devices. Anodization is carried out under well-controlled constant-current conditions in an aqueous electrolyte containing ammonium pentaborate and ethylene glycol. Experimentally, we show that anodic oxidation substantially reduces the ultraviolet (UV) reflectance and induces a monotonic redshift of the reflectance minimum as the anodic oxidation cutoff voltage (V_ocv) increases. Finite-difference time-domain (FDTD) simulations based on spectroscopic ellipsometry data reproduce the measured spectra with good fidelity for most samples, validating the extracted optical constants. By comparing samples prepared at different current densities and oxidation times, we identified V_ocv as the primary parameter controlling the reflectance response, because it determines the thickness and effective optical properties of the anodic TiO_x layer. Under optimized conditions, reflectance values below 1% in the 320.9–340.2 nm wavelength range and below 2% in the 316.3–346.3 nm range are achieved, indicating a significant enhancement in potential absorptance. These results demonstrate that anodic oxidation provides a simple, post-fabrication, and voltage-tunable route for engineering the UV optical response of Ti-based TES structures and for enhancing their potential QE by suppressing reflection losses. Full article

In mechanical engineering, interest in reliable and practicable technologies for nano- and microstructuring of tool surfaces is increasing. Femtosecond laser structuring offers a promising approach that combines high processing speeds with high precision. However, a knowledge gap remains regarding the optimal process parameters for achieving specific surface patterns on hot-work tool steel substrates. The current study aims to investigate the effects of laser scanning parameters on the formation of self-organized surface structures and the resulting topography and morphology. Therefore, samples were irradiated using a 300 fs laser with linearly polarized light (λ = 1030 nm). Scanning electron microscopy revealed four structure types: laser-induced periodic surface structures (LIPSSs), micrometric ripples, micro-crater structures, and pillared microstructures. The results for surface area and line roughness indicate that high laser pulse overlaps lower the strong ablation threshold more effectively than high scanning line overlaps, promoting the formation of pillared microstructures. For efficient ablation and increased surface roughness, higher pulse overlaps are therefore advantageous. In contrast, at low fluences, higher scanning line overlaps support a more homogeneous formation of nanostructures and reduce waviness. Full article

Cavitation erosion is a critical problem for many engineering components, such as ship propellers, diesel engine exhaust valves, cylinder liners, pump impeller blades, hydraulic turbines, and bearings, which are exposed to high-velocity flowing fluids or to vibratory fluid motion. It represents a mechanical degradation of the surface caused by the continuous collapse of bubbles in the surrounding liquid, which seriously affects flow efficiency and component service life, increasing maintenance frequency and refurbishment costs. The intensity and evolution of the cavitation erosion phenomenon depend on the hydrodynamic conditions to which the component surface is exposed, the properties of the liquid, and the judicious selection of the most suitable material. This paper aims to modify the microstructure of a Ni-based superalloy by applying recrystallization annealing heat treatment in order to obtain surfaces resistant to cavitation erosion for components that handle fluids under local pressure fluctuations. Experimental tests are carried out using a vibratory apparatus with piezoceramic crystals operating at a frequency of 20 kHz and an amplitude of 50 µm. The cavitation erosion performance of the Ni-based superalloy INCONEL 625, heat treated by recrystallization annealing, are compared with that of austenitic stainless steel AISI 316L subjected to solution treatment. For both metallic alloys, based on mass loss measurements, the characteristic time-dependent curves of the mean cumulative erosion penetration depth, MDE(t), and the mean erosion rate, MDER(t), are determined. The comparison of these curves and of the parameters defined and recommended by the ASTM G32 standard demonstrates that, for the Inconel 625 superalloy, resistance to cavitation erosion increases by 77–81% compared to that of AISI 316L austenitic stainless steel. X-ray diffraction analyses (XRD) show that, in the microstructure of the Inconel 625 superalloy, in addition to austenite, MC-type carbides, M₂₃C₆ carbides, and intermetallic phases γ″ = Ni₃(Nb, Al, Ti) and δ = Ni₃(Nb, Mo) are also present. Full article

High-entropy alloys (HEAs) represent one of the most promising emerging material families, particularly for advanced surface engineering applications. In this work, a near-high-entropy alloy (near-HEA) coating was produced on a 316L stainless steel substrate using laser metal deposition (LMD) from a powder mixture of Inconel 625, Cr and Mo, without the intentional addition of Fe. Due to dilution from the substrate, the resulting alloy contained elevated Fe content while maintaining Cr, Ni and Mo concentrations within the generally accepted compositional range of HEAs. The deposited layer exhibited a dual-phase microstructure consisting of a face-centered cubic (FCC) phase and a highly distorted tetragonal phase forming a periodic network with a characteristic length scale of several hundred nanometers. The hardness of the coating increased to approximately three times that of the substrate, reaching values of 600–700 HV. To further modify the surface properties, laser-induced periodic surface structures (LIPSS) were generated on the polished coating using femtosecond pulsed laser irradiation at different energy densities. The morphology and subsurface structure of the resulting periodic patterns were investigated by scanning electron microscopy. LIPSS with characteristic dimensions ranging from the micrometer to nanometer scale were successfully produced. Cross-sectional analyses revealed that the underlying dual-phase microstructure remained continuous within the laser-structured regions, indicating that LIPSS formation occurred predominantly via metallic ablation without significant phase transformation or amorphization. These results demonstrate the combined applicability of LMD and femtosecond laser structuring for producing mechanically enhanced, micro- and nanostructured near-HEA coatings with potential for advanced surface-related functionalities. Full article

This work presents microwave sensing of ethanol concentration in ethanol–water mixtures using a low-cost 3D-printed cavity resonator. The objective is to realize a customizable liquid sensor that combines high measurement accuracy with inexpensive, in-house fabrication. The cylindrical cavity is fabricated from polylactic acid using fused deposition modeling and metallized on its inner surface with copper tape. The resonator operates in the TM₀₁₀ mode with a resonant frequency of 3 GHz. A standard 1.5 mL centrifuge tube is used as a modular sample holder and inserted through a circular opening in the top endcap of the cavity. The quality factor of the air-filled cavity is 200, which decreases to 37.3 when the cavity is loaded with deionized water. As an application example, ethanol concentrations in ethanol–water mixtures are determined using both the resonant frequency and the peak magnitude of the transmission coefficient (|S₂₁|). For ethanol concentrations between 20% and 100%, the concentration can be accurately extracted from the resonant frequency alone: a quartic calibration curve yields a coefficient of determination $R^2=0.9992$, an average sensitivity of approximately 8.4 MHz/% ethanol, and a mean absolute error of about 0.58% on the calibration set. In addition, a cubic calibration based on the peak $\mid S_{21}\mid$ over the 0–90% concentration range achieves a mean absolute error of approximately 0.52% on the calibration set and about 0.55% on an independent validation set covering 5–85% ethanol. Comparison with conventionally machined metal cavities shows that the proposed 3D-printed cavity achieves a high Q-factor at significantly lower cost and can be fabricated in-house using a standard 3D printer. These results demonstrate metrologically relevant performance in terms of low error and high sensitivity using a low-cost and easily replicable platform for microwave liquid sensing in biomedical and chemical engineering applications. Full article

Natural-fiber biocomposites are increasingly viewed as promising materials for sustainable engineering. However, their broader adoption remains constrained by coupled challenges related to interfacial compatibility, moisture sensitivity, environmental durability, processing limitations, and end-of-life trade-offs. Rather than treating fiber selection, matrix chemistry, processing routes, durability, and sustainability as independent considerations, this review emphasizes their interdependence through the fiber–matrix interface, which governs stress transfer, moisture transport, and long-term property evolution. It provides a comprehensive and integrative analysis of natural-fiber–reinforced polymer composites, encompassing plant-, animal-, and emerging bio-derived reinforcements combined with bio-based, biodegradable, and selected synthetic matrices. Comparative analysis across the literature demonstrates that interfacial engineering consistently dominates mechanical performance, moisture resistance, and property retention, while mediating trade-offs among stiffness, toughness, recyclability, and biodegradability. Moisture transport and environmental ageing are examined using thermodynamic and diffusion-controlled frameworks that link fiber chemistry, interfacial energetics, swelling, and debonding to performance degradation. Fire behavior and flame-retardant strategies are reviewed with attention to heat-release control and their implications for durability and circularity. Processing routes, including extrusion, injection molding, compression molding, resin transfer molding, and additive manufacturing, are assessed with respect to fiber dispersion, thermal stability, scalability, and compatibility with bio-based systems. By integrating structure–property relationships, processing science, durability mechanisms, and sustainability considerations, this review clarifies how natural-fiber biocomposites can be designed to achieve balanced performance, environmental stability, and circular life-cycle behavior, thereby providing guidance for the development of systems suitable for near-term engineering applications. Full article

This study aims to enhance the corrosion property of 17-4PH martensitic stainless steel, a material commonly used in industrial applications including nuclear power components, to enhance its performance in borate buffer solutions. The study employed plasma-based low-energy nitrogen ion implantation at temperatures ranging from 350 °C to 550 °C for 4 h to modify the steel surface. Microstructural characterization via XRD and TEM revealed the formation of a nanocrystalline nitrided layer, with thickness increasing from 11 to 27 μm and surface nitrogen concentration rising from 29.7 to 33.1% as temperature increased. Correspondingly, the nanocrystalline grains coarsened from an average size of 2 nm to 15 nm. The main findings showed that all nitrided layers significantly improved general corrosion resistance in pH 8.4 borate solution compared to the unmodified steel. An optimal performance with a corrosion potential of −169.4 mV(SCE) and a passive current density of 0.5 μA/cm² was achieved at 450 °C, accompanying the development of a denser passive film with high polarization resistance and lower defect density. It is concluded that the high interstitial nitrogen concentration within the nanocrystalline γ′_N accelerates passivation kinetics and enhances corrosion resistance, with the applied point defect model clarifying the underlying improvement mechanism. Full article

Lunar dust exhibits exceptionally strong adhesion, abrasiveness, and electrostatic charging due to long-term exposure to extreme temperature cycling (−183 °C to 127 °C), high vacuum, and intense radiation. With the rapid advancement of global lunar exploration programs and the planned construction of lunar bases, lunar dust has become a critical threat to exploration equipment, spacesuits, and spacecraft sealing systems. This paper systematically reviews recent progress in lunar dust mitigation technologies from the perspective of engineering application requirements. Key micro-mechanism factors governing dust adhesion and removal efficiency are analyzed, and the protection mechanisms and application scenarios of traditional lunar dust mitigation technologies are comprehensively discussed, including both active and passive approaches. Active protection technologies generally provide effective dust removal but suffer from high energy consumption, whereas passive strategies can reduce dust adhesion but face challenges in mitigating dynamic dust accumulation. To overcome these limitations, recent studies have increasingly focused on active–passive synergistic strategies that integrate surface modification with dynamic dust removal. Such approaches enable improved efficiency and adaptability by combining long-term dust resistance with real-time removal capability. Based on the latest research advances, this paper further proposes an integrated technical framework for the engineering design of efficient lunar dust protection. Full article

Transparent conductive SnO₂ films, promising for application in electronic engineering, were obtained by sol–gel synthesis via mixing SnCl₂∙2H₂O and NH₄F solutions, followed by deposition onto glass substrates by centrifugation and heat treatment at 450 °C. The physicochemical processes of SnO₂ crystallization in water–alcohol solutions of SnCl₂ were analyzed depending on the concentration of the crystallization initiator NH₄F and the alcohols used. The sol–gel processing of the thin films was investigated using a Latin square approach. Three factors affecting the film formation conditions were varied at three levels to determine the best combination of film properties involving the maximum transparency and lowest specific electrical resistance. The effect of solvent type (ethanol, 1-butanol and isopropanol), the amount of introduced fluorine (5, 10, and 15 at. %) and the number of deposited layers (10, 15, and 20) on the composition, morphology, crystallization features, transparency and specific surface resistance of the synthesized thin films was studied. The obtained films of ~200–340 nm thickness exhibited ~78%–95% transparency in the visible spectrum range and specific surface resistance (ρ_s) from ~10⁹ to >10¹² Ω/sq. The optimal combination of thin (~250 μm) SnO₂<Sn> film target performances including transparency 84% and specific surface resistance ~10⁹ Ω/sq. was achieved in the case of their preparation in isopropanol with an average concentration of NH₄F (10 at. % F) and spin-on deposition of 20 layers. Full article

Adaptive winglets improve aerodynamic efficiency by enabling geometry adjustments tailored to flight conditions. In this study, an engineering-oriented optimization framework is developed and applied to numerical aerodynamic evaluations based on the wing–winglet configuration of a KC-135 aircraft, under representative takeoff, climb, and cruise conditions. A Plackett–Burman design is employed to screen the 10 kinds of winglet geometric parameters, from which the dominant variables affecting drag are identified. Subsequently, response surface methodology is used to construct surrogate models and determine optimal parameter combinations for each flight phase, thereby defining a feasible morphing envelope for adaptive winglet operation. The results indicate that a coupled morphing of winglet height and cant angle constitutes the most effective morphing mode. Across the takeoff, climb, and cruise phases, the optimal morphing envelope involves a continuous transition from Height = 0.20b/2 and Cant angle = 86.3° at takeoff, to Height = 0.192b/2 and Cant angle = 8.2° during climb, and finally approaching the baseline configuration (Height = 0.135b/2, Cant angle = 20°) at cruise, while achieving a maximum drag reduction efficiency improvement of up to 8.8% at the climb phase. Full article

Simulation-based training systems are increasingly deployed to prepare learners for complex, safety-critical, and dynamic work environments. While advances in computing have enabled immersive and data-rich simulations, many systems remain optimized for procedural accuracy and surface-level task performance rather than the macrocognitive processes that underpin adaptive expertise. Macrocognition encompasses higher-order cognitive processes that are essential for performance transfer beyond controlled training conditions. When these processes are insufficiently supported, training systems risk fostering brittle strategies and negative training effects. This paper introduces a macrocognitive design taxonomy for simulation-based training systems derived from a large-scale meta-analysis examining the transfer of macrocognitive skills from immersive simulations to real-world training environments. Drawing on evidence synthesized from 111 studies spanning healthcare, industrial safety, skilled trades, and defense contexts, the taxonomy links macrocognitive theory to human–computer interaction (HCI) design affordances, computational data traces, and feedback and adaptation mechanisms shown to support transfer. Grounded in joint cognitive systems theory and learning engineering practice, the taxonomy treats macrocognition as a designable and computable system concern informed by empirical transfer effects rather than as an abstract explanatory construct. Full article

The functionalization of molecules on C₆₀ is a promising engineering approach, as non-covalently governed fullerene surfaces facilitate reversible host–guest recognition, tunable electronic communication, and conformationally adaptive molecular adsorption. In this work, spin-resolved simulations using density functional theory (DFT) were conducted to examine the interaction between a newly identified arylalkanone isolated from the medicinal species Myristica ceylanica and the nanocarbon framework of C₆₀ fullerene, including doped configurations incorporating group III elements (B, Al, Ga, In and Tl). The results indicate that the arylalkanone binds to pristine C₆₀ through an exothermic, energetically favourable binding process, supporting thermodynamically viable molecular uptake. Among the doped models, B substitution exhibits the greatest overall thermodynamic preference; however, Al doping produces the most pronounced enhancement in binding energy, identifying the Al-doped configuration as the most effective surface-uptake architecture in relative terms. Across all complexes, a small amount of charge transfer is noted, signifying weak yet persistent electronic coupling between the ligand and the carbon carrier. Additionally, all doped fullerenes demonstrate induced magnetic behaviour, a property of increasing relevance in spintronics research, suggesting that these complexes may hold future value in spin-dependent electronic and molecular-recognition-guided nanoscale biomedical engineering. Full article

Understanding the competitive adsorption mechanism is crucial for the rational design of CO₂ adsorbents. In this work, the surface of zeolite 5A was modified with varying concentrations of n-octadecylphosphonic acid (ODPA) to enhance the adsorptive separation of CO₂ over C₃H₆. With a 0.01 mol/L concentration of ODPA, the modified zeolite 5A achieves CO₂/C₃H₆ ideal selectivity over 73 at 298 K, a substantial improvement over the pristine zeolite 5A, which exhibits a selectivity of 6.07. The Sips isotherm model provides an excellent fit to the experimental data, offering insights into the adsorption mechanism, with a calculated enthalpy change of −30.70 kJ/mol for CO₂ and −16.54 kJ/mol for C₃H₆, along with favorable Gibbs free energy changes ranging from −9.00 to −3.54 kJ/mol for CO₂ and −4.96 to −2.04 kJ/mol for C₃H₆ over the temperature range of 298–373 K. Kinetic analysis reveals faster diffusion in pristine zeolite 5A; however, surface modification significantly enhances CO₂/C₃H₆ selectivity while maintaining balanced adsorption capacity. Adsorption uptakes of CO₂ and C₃H₆ in pristine zeolite 5A follow the pseudo-first-order model and pseudo-second-order model, respectively. Pristine zeolite 5A shows rapid adsorption, with a CO₂ adsorption capacity of 4.10 mmol/g with a rate constant of 2.60 min⁻¹, and a C₃H₆ adsorption capacity of 1.99 mmol/g with a rate constant of 0.34 min⁻¹. The modification with ODPA increases adsorption energy barriers, with CO₂ activation energy reaching 5.18 kJ/mol and C₃H₆ activation energy up to 15.63 kJ/mol, while tetrahydrofuran washing restores site accessibility, demonstrating tunable diffusion and adsorption behavior. These findings lay the foundation for designing high-efficiency, and selective adsorbents through targeted surface engineering. Full article