Search Results (978)

In recent years, hybrid materials have been widely applied in the cultural heritage conservation field, especially to preserve color pigments. Among these, one of the most problematic (in terms of conservation science) is the red pigment cinnabar/vermilion. The challenge of this work was to prepare a hybrid coating consisting of a fluorinated polymer (known to protect cinnabar/vermilion), further modified with an inorganic filler based on anatase TiO₂. The latter is suitable because it is functionalized with quenchers, the particles are well above the nanoscale (≥200 nm in diameter), and it was added to the polymer matrix in small quantities. These characteristics made it suitable as a hybrid coating for protecting natural cinnabar, as demonstrated by the results obtained through a multi-analytical approach, based on multispectral imaging, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) coupled with energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF), contact angle, spectrophotometry and mechanical tests, which were applied to evaluate the performances of the hybrid coating on laboratory specimens (after aging) and original samples. The experimental results provide insight into both the physicochemical decomposition mechanism of natural cinnabar under laboratory-simulated aging conditions and the benefits of the coating. In particular, the treatment did not induce electrochemical changes in the mercury, which remained in its oxidized state (+2) rather than being further reduced to elemental mercury (Hg⁰), the species responsible for the blackening of cinnabar/vermilion (also combined with meta-cinnabar). In the oxidized form (Hg²⁺), the protein binder was altered, yet the application of the hybrid coating did not cause further physicochemical changes (i.e., red shift) to the Hg²⁺/egg-based binder system. This was also reflected in the color properties, which underwent no significant alteration. Finally, the mechanical tests yielded satisfactory results, particularly regarding water vapor permeability and treatment efficiency (even eight months after the initial application, although studies on the same samples are still ongoing). The hybrid coating was ultimately applied to original samples collected at Poggio Spaccasasso (Tuscany, Italy), which could be representative of prehistoric artworks based on natural cinnabar and traces of prehistoric adhesives made from beeswax, natural oils, and plant resins. Full article

The use of nanoscale materials has expanded rapidly in recent decades, with titanium dioxide (TiO₂) nanoparticles among the most widely produced. Their increasing environmental release raises concerns about ecosystem-level effects. A key mechanism of toxicity is the generation of reactive oxygen species (ROS), although these effects strongly depend on particle properties, including crystalline form, size, morphology, surface characteristics, and exposure conditions. Here, we assessed and compared the ecological impacts of anatase and rutile TiO₂ nanoparticles across prokaryotic and eukaryotic systems, including aquatic microbial communities, microbial cultures, plant bioassays (Sinapis alba, Triticum aestivum), the SOS Chromotest, and zebrafish (Danio rerio) assays. Nano-TiO₂ exposure markedly restructured freshwater microbial communities by suppressing sensitive taxa (e.g., Actinomycetota, Flavobacterium, and Limnohabitans) while enriching more tolerant genera such as Pseudomonas, Sediminibacterium, Haliscomenobacter, and Hydrogenophaga. These shifts likely reflect differences in cell-envelope structure, biofilm formation, and antioxidant capacity. The two investigated TiO₂ nanoparticle types showed distinct biological effects: rutile was associated with more pronounced microbial community shifts and bacterial cell damage, whereas anatase caused stronger responses in plant assays, particularly by impairing hypocotyl growth and plant water balance. Besides the limited acute genotoxicity revealed by the SOS Chromotest, TiO₂ nanoparticles did not significantly affect survival or final larval body length in the zebrafish embryo assay under the tested conditions; however, the hatching delay observed at the highest concentration indicated a sublethal developmental effect. Overall, our results show that TiO₂ nanoparticle toxicity cannot be generalized across biological systems and suggest that biological responses depend on the combined influence of particle characteristics and organism-specific structural and physiological traits. Full article

Aerospace die forgings are safety-critical structural products whose service performance is governed by coupled microstructural evolution across multiple length scales rather than by any single descriptor. This review critically synthesizes recent progress in multiscale characterization and process–structure–property analysis of aerospace die forgings, with emphasis on forged titanium alloys, wrought nickel-based superalloys, and high-strength aluminum alloys. A practical framework is first established by linking macroscale metal-flow integrity and defect control with mesoscale gradients, microscale grain-boundary and texture evolution, and nanoscale precipitation, segregation, and interface states. The principal characterization routes are then discussed, including X-ray diffraction, EBSD/3D-EBSD, TEM/STEM, atom probe tomography, tomography-based defect evaluation, and correlative workflows. The alloy-specific sections are organized around mechanisms and property consequences rather than isolated micrographs. Finally, the review discusses how multiscale descriptors can support crystal-plasticity, phase-field, cellular-automata, and ICME-oriented modeling, and identifies future priorities in three-dimensional characterization, quantitative descriptor extraction, uncertainty-aware modeling, environmental degradation assessment, and closed-loop process optimization. Overall, the performance of aerospace die forgings is shown to depend on coordinated control of phase stability, grain-boundary network evolution, precipitation state, defect population, and location-dependent heterogeneity across the full manufacturing route. Full article

The optimization and the engineering development of additive manufacturing (AM) products both require accurate, non-destructive techniques to extract their mechanical performances. The Instrumented Indentation Test (IIT) has such a potential, although it currently lacks standard procedures that are suitable for analyzing materials which are affected by internal residual stress (RS). Additionally, nanoindentation testing suffers from the presence of indentation size effects (ISE), which hamper the possibility of correlating the measured mechanical performance at different indentation depths or peak loads using the standard indentation hardness (H_IT) and modulus (E_IT). This paper presents a novel IIT methodology that is based on new indentation parameters, namely the loading stiffness rate (LSR) and the rate-derived hardness (H_R), which are then used to assign the desired mechanical performances of an L-PBF 316L austenitic stainless-steel alloy obtained via multiload/multiscale IIT strategy. The mean values of LSR, H_R, H_IT, and E_IT on the macroscale were 57.3 ± 1.4 GPa, 2.33 ± 0.059 GPa, 2.41 ± 0.13 GPa, and 201 ± 7.8 GPa, respectively, whereas on the nanoscale they were 56.1 ± 5.1 GPa, 2.30 ± 0.21 GPa, 3.00 ± 0.36 GPa, and 219 ± 24 GPa, respectively. Unlike the standard H_IT, the new indentation parameters of the nano- and macro-IITs are within the standard deviation, proving their ISE-free property. The obtained E_IT was slightly higher than the reference Young’s modulus (~190 GPa) of the 316L stainless steel. The loading secant stiffness versus depth plot can be used to assess the susceptibility of RS to relax during indentation, which is an important performance factor for the engineering design of AM components. The successful correlation that has been found between electron backscatter diffraction (EBSD) analysis (in terms of crystal anisotropy, grain size, and dislocation density) and nanoindentation testing at three subregions of the core zone of the investigated deposit confirms the validity of the proposed methodology. The proposed methodology is a step towards the full determination of the three Ps, that is, process, properties, and performance of advanced AM products. Full article

Guided Bone Regeneration (GBR) is a pivotal technique in dental and orthopedic applications for regenerating bone in areas of deficiency. Natural polymers such as collagen, chitosan, alginate, and gelatin have emerged as essential materials in GBR due to their biocompatibility, biodegradability, and bioactivity. These polymers not only provide a scaffold for bone regeneration but also support cellular adhesion, proliferation, and differentiation. Despite their benefits, challenges such as variable degradation rates, insufficient mechanical strength, and limited bioactivity hinder their optimal clinical use. To address these limitations, ongoing research focuses on enhancing the properties of natural polymers. Composite materials combining fast- and slow-degrading polymers are being developed to achieve consistent degradation rates. Surface modifications, including nanoscale texturing and growth factor coatings, are improving bioactivity. Nanotechnology further enhances the structural and therapeutic potential of GBR materials, while advancements in 3D bioprinting enable the creation of customized scaffolds with precise architecture. These innovations aim to bridge the gap between biological compatibility and clinical functionality, making natural polymers more adaptable and effective in GBR. This review highlights the mechanisms, challenges, and advancements in natural polymers for GBR, emphasizing their potential to transform bone regeneration into a more reliable and patient-centered approach. Full article

ZERODUR glass-ceramic is widely used in ultra-precision optical components because of its extremely low thermal expansion and excellent dimensional stability. However, its two-phase microstructure, composed of crystalline and amorphous phases with different mechanical properties, may cause non-uniform material removal during magnetorheological polishing, thereby limiting further improvement of nanoscale surface quality. To address this issue, this study investigates the effect of oxide abrasives on the surface homogenization of ZERODUR. A single-particle abrasive–workpiece contact model based on modified Hertz contact theory and elastoplastic contact analysis was established to compare the indentation responses of CeO₂, SiO₂, and ZrO₂ abrasives in the two constituent phases. Magnetorheological polishing experiments were conducted under identical process parameters, and the polished surfaces were characterized by AFM over scan areas of 2 μm × 2 μm, 5 μm × 5 μm, and 10 μm × 10 μm. The results show that all three abrasives improved the surface quality of the ring-polished substrate, with ZrO₂ achieving the best surface homogenization performance. The lowest roughness, Ra = 0.104 nm, was obtained at a 2 μm field of view, and the ZrO₂-polished surface showed more stable roughness evolution across different scan sizes than the CeO₂- and SiO₂-polished surfaces. These results indicate that the elastic modulus, hardness, and mechanical compatibility of abrasives with ZERODUR play key roles in governing contact stress, indentation behavior, and final surface quality. This work addresses the lack of mechanistic understanding of abrasive-dependent surface homogenization in the magnetorheological polishing of two-phase ZERODUR glass-ceramic. The main innovation is the integration of contact-mechanics-based abrasive–workpiece modeling with multi-scale AFM characterization to clarify how abrasive mechanical compatibility affects nanoscale surface uniformity and to guide abrasive selection for ultra-smooth optical manufacturing. Full article

Monocrystalline silicon, with its high refractive index, high infrared transmittance, and excellent dimensional stability, serves as a key optical component in high-energy laser systems, infrared imaging, and guidance fields. Its processing quality directly affects the performance indicators of related systems. To address the challenges of nanoscale precision shape and property control during processing, methods such as ultra-precision cutting, magnetorheological polishing, laser micromachining, ion beam processing, plasma etching, and chemical–mechanical polishing have been adopted to improve the surface shape accuracy and repair defects of monocrystalline silicon components. This paper reviews the research progress of key technologies, including nanoscale precision surface shape control manufacturing technology, nanoscale precision property control generation methods, and combined processes for its nanoscale shape and property control, providing technical support for achieving nanoscale precision shape and property control manufacturing of monocrystalline silicon components. Full article

Polyacrylamide (PAM) is widely used to improve sandy muck in shield tunneling due to its excellent physicochemical properties. During shield excavation, the temperature of excavated soil varies with geological depth and equipment heat transfer, making it necessary to investigate the temperature effect on the performance of PAM-modified sandy muck. In this study, molecular dynamics (MD) simulations are employed to construct a (PAM, H₂O)/α-SiO₂ interfacial model. The microstructural evolution and interfacial interaction characteristics between PAM molecules and the α-SiO₂ substrate are analyzed at the nanoscale under different temperature conditions. A structure–performance–mechanism relationship is established, forming a conceptual framework of the “configuration–interaction energy–stability” mechanism for PAM-modified sandy muck. The main findings are as follows: (1) The PAM exhibits the most stable interfacial bonding with α-SiO₂ between 278 K and 318 K, primarily governed by electrostatic attraction and hydrogen-bond synergy. (2) Within this temperature range, PAM forms a dense and stable interfacial adsorption structure, whereas both thermodynamic stability and structural integrity decline outside it. (3) At 318K, the PAM/α-SiO₂ system shows the most favorable hydrogen-bonding behavior, with orderly alignment of PAM and H₂O molecules and optimal chain flexibility and adhesion capacity. Therefore, 318 K is the upper temperature limit reference point at which the improvement effect of PAM remains the most stable, providing theoretical guidance for temperature-controlled soil conditioning in shield tunneling. Full article

Camel milk is increasingly recognized as a premium functional food, attributed to its rich nutraceutical compounds. Recent research has concentrated on the nanoscale extracellular vesicles derived from camel milk (CM-EVs), which exhibit distinctive properties. This review examines the methodologies for isolating and characterizing CM-EVs, alongside their potential health benefits in functional foods and nutraceuticals. CM-EVs have the capacity to safeguard functional proteins, noncoding RNAs, and bioactive lipids from degradation within the gastrointestinal tract, rendering them particularly suitable for incorporation into infant formulas, adult dietary supplements, and nutraceuticals targeting chronic inflammatory and metabolic disorders. Preclinical models indicate that CM-EVs can mitigate oxidative stress, enhance intestinal barrier integrity, and modulate gut microbiota, thereby contributing to the reduction in colonic injury and inflammation. Nonetheless, the majority of these findings are derived from laboratory and animal studies, highlighting a substantial deficiency in human clinical trials. Critical research gaps remain, necessitating further investigation into the elucidation of molecular mechanisms, assessment of long-term safety, evaluation of bioavailability, and compatibility with dairy processing techniques. This review underscores the significance of CM-EVs as bioactive food components and delineates research priorities, such as standardizing isolation methods, investigating food matrix integration, and providing translational evidence for their application in nutrition and preventive medicine. Full article

The effects of Mn/RE (Nd, Gd) multi-modification on the microstructure and high-temperature compressive creep properties of Mg–8.0Al alloys were investigated. The dominant intermetallic phases in the as-cast microstructure are β-Mg₁₇4Al₁₂, Al₂(Gd,Nd), Al₁₁(Gd,Nd)₃, Al₈(Gd,Nd)Mn₄, and Al₁₀Mn₂(Gd,Nd). The detailed structures of various intermetallics were revealed by TEM; the results indicate that Mn addition promotes grain refinement and facilitates the precipitation of lath-shaped and spherical β-Mg₁₇Al₁₂ in as-cast Mg–Al–RE alloys, resulting in increases in the tensile strength and elongation of the 1.0Mn alloy by 26.5% and 92.1%, respectively. Additionally, thermally stable micron-scale Al₈(Gd,Nd)Mn₄ and Al₁₂(Gd,Nd)₂Mn₅, along with dynamically precipitated spherical nano-sized AlGd and AlNd particles in the α-Mg matrix, were innovatively observed in compression-crept specimens tested at 200 °C and 60 MPa; these phases play a key role in improving high-temperature creep resistance. A significant finding is that excessive Mn addition deteriorates creep performance, which is attributed to excessive grain refinement and the consequent increase in the contribution of grain boundary sliding during creep. However, the negative effect of grain boundary sliding—caused by grain refinement—on creep performance can be balanced by the strengthening effect of Al–Mn–Gd phases and the dynamic precipitation of nanoscale Al–RE particles. This paper provides new insights for designing Mg–Al–Nd–Gd–Mn alloys with both excellent high-temperature creep resistance and significantly enhanced mechanical properties. Full article

Nanobubbles have attracted increasing interest in food systems because they can modify gas dispersion, interfacial transport, washing performance, preservation processes, and the structures of dispersed matrices. However, their behavior cannot be interpreted based on bubble size alone. Proteins, polysaccharides, lipids, salts, colloidal particles, gas composition, and processing conditions can alter interfacial adsorption, gas transfer, bubble persistence, and matrix organization in food systems. This review examines the physicochemical mechanisms proposed to explain nanobubble persistence and functionality, with an emphasis on surface charge, interfacial adsorption, gas supersaturation, confinement, and interactions with food biopolymers. A central distinction is made between passive nanobubble-containing systems and externally activated systems involving hydrodynamic cavitation, ultrasound, plasma, pressure fluctuations, and reactive gases. Under passive conditions, nanobubbles mainly act as gas–liquid interfaces that influence local transport and adsorption. In activated systems, microbial inactivation, reactive oxygen species formation, and apparent mass-transfer enhancement often arise from external energy input, gas chemistry, turbulence, and transient supersaturation rather than from nanobubbles alone. Interfacial stability is used here as an organizing concept to connect nanobubble persistence, food-matrix interactions, generation methods, characterization limitations, and interpretation of reported technological effects. Current methods, such as dynamic light scattering and nanoparticle tracking analysis, provide useful size and concentration estimates but cannot unambiguously distinguish nanobubbles from protein aggregates, fat droplets, micelles, polysaccharide assemblies, and other colloidal structures in complex matrices. Therefore, reliable interpretation requires complementary methods, appropriate controls, and standardized reporting of gas composition, generation method, energy input, matrix properties, and processing conditions. Thus, nanobubble-containing technologies show promise for food processing; however, their value depends on the separation of nanoscale interfacial effects from concurrent hydrodynamic, chemical, and matrix-dependent phenomena. Full article

Polyhydroxyalkanoates (PHAs) are bio-based, biodegradable polyesters increasingly explored as sustainable biomaterials for regenerative medicine. This review summarizes recent advances in PHA-based bone substitute materials, highlighting their properties, fabrication methods, and biological performance. PHAs combine biocompatibility, tunable mechanical behavior, and degradation into non-toxic metabolites, while copolymerization and monomer selection modulate the stiffness, crystallinity, and resorption rate. Processing techniques such as solvent casting, electrospinning, and additive manufacturing allow the production of porous architectures that mimic bone extracellular matrix. Electrospinning is particularly suitable for nanoscale fibrous matrices, whereas 3D printing enables patient-specific scaffolds with controlled geometry and interconnected porosity. Scaffold performance can be further improved through the incorporation of osteoconductive fillers, including hydroxyapatite, β-tricalcium phosphate, bioactive glasses, graphene oxide, and carbon nanotubes, as well as through drug-delivery and pro-angiogenic functionalization. In vitro and in vivo studies consistently report favorable cytocompatibility, enhanced osteogenic differentiation, vascularization, and effective repair of bone defects in animal models. However, clinical translation remains limited by production costs, variability in polymer quality, thermal processing constraints, and regulatory challenges. Future progress will rely on more efficient biosynthesis, medical-grade purification, multifunctional scaffold design, and stronger collaboration between academia, industry, and clinicians to unlock the full potential of PHAs in regenerative bone therapies. Full article

The interaction between light and chiral plasmonic metasurfaces provides a powerful mechanism for controlling polarization states at the nanoscale. Utilizing displacement Talbot lithography for large-area fabrication, we characterized the chiroptical response by measuring the evolution of Stokes parameters to quantify phase retardation between orthogonal polarization components. To elucidate the underlying physical mechanism, we employ a hybrid finite element method and rigorous coupled-wave analysis approach to investigate the behavior of the far-field and local-field configurations. Our results reveal that the phase shift is highly sensitive to symmetry-breaking features, where the interplay between different modes dictates the overall circular dichroism signal. Furthermore, the analysis of local field plots suggests specific contributions of plasmonic modes to the chiroptical response. We conclude that the phase shift effects, characterized via Stokes parameters and modal analysis, provide a robust metric for engineering chiroptical properties in these systems. This work establishes a fundamental framework for developing compact polarization-control elements and enhances the understanding of phase-modulated light-matter interactions in chiral plasmonic metasurfaces. Full article

The pearlitic microstructure, comprising alternating lamellae of ferrite and cementite, provides a favorable combination of strength, toughness, and wear resistance. Consequently, pearlitic steels have been widely utilized in pipeline systems due to their advantageous mechanical properties and cost-effectiveness. These characteristics also render pearlitic steel pipelines promising candidates for hydrogen transport infrastructure, particularly in the context of repurposing existing natural gas networks. However, interactions between hydrogen and the pearlitic microstructure raise significant concerns regarding hydrogen embrittlement, a phenomenon that can substantially degrade mechanical performance and compromise long-term structural integrity. Experimental observations indicate that pearlitic microstructures are particularly susceptible to hydrogen embrittlement, largely due to the high density of ferrite–cementite interfaces, which act as effective hydrogen trapping sites. These detrimental effects motivate the present study, which aims to develop a deeper understanding of nanoscale mechanisms of hydrogen-assisted crack initiation and propagation in pearlitic microstructures. In this work, molecular dynamics simulations are employed to investigate the initiation and propagation of hydrogen-affected cracks in pearlitic microstructures, considering lamellar orientations both parallel and perpendicular to the applied tensile loading direction. The analysis focuses on the synergistic interaction between hydrogen-enhanced decohesion (HEDE), which promotes interfacial separation due to hydrogen segregation, and hydrogen-enhanced localized plasticity (HELP). Full article

In this paper, we investigate the existence and positivity of solutions for a class of twelfth-order nonlinear boundary value problems that naturally arise in the mathematical modeling of elastic and micro-mechanical systems. The considered model incorporates higher-order derivatives to account for nonlocal and gradient effects that commonly appear in the analysis of micro- and nano-scale elastic structures. By employing the Leray–Schauder nonlinear alternative and fixed point theorems, we establish sufficient conditions for the existence of at least one positive solution. The analysis relies on the explicit construction and properties of the associated Green’s function, which plays a fundamental role in deriving upper and lower bounds for the nonlinear term. The obtained results extend and generalize earlier works on sixth, eighth and tenth-order problems to the twelfth-order case. Finally, numerical examples are presented to illustrate the applicability and accuracy of the theoretical findings. The results provide a rigorous analytical foundation for the study of high-order elastic models and micro-scale structural stability. Full article