Search Results (3,458)

In this study, a surface texture design technique for 3D-extruded prototype products was developed. The study determines some target functional properties of polymer-made items. Four series of experimental samples (acrylonitrile–butadiene–styrene (ABS), thermoplastic polyurethane (TPU), polylactide (PLA), and polyethylene terephthalate glycol (PETG)) were 3D-printed using the fused filament fabrication (FFF) approach. The morphology and hydrophilic/hydrophobic balance of the surfaces of the experimental samples were regulated directly by the 3D design and by gas-phase fluorination techniques. The observed distilled water and ethylene glycol edge wetting angles of the surfaces of the experimental samples were determined by a 3D filament stroke arrangement. It was shown that varying the 3D design promoted hydrophobization and provided anisotropic wetting (the distilled water edge angle of the same sample varies from 76 to 116 degrees). The textured surfaces simultaneously demonstrated hydrophilicity in one direction and hydrophobicity in the other. The changing of the fluorine-containing gas mixture surface treatment duration allowed us to alter the hydrophilic/hydrophobic balance of 3D-extruded prototypes. The fluorination kinetics of the experimental samples were studied empirically. The combination of macroscopic surface design (through FFF 3D printing) and microscopic surface modification (through gas-phase fluorination) permitted a significant reduction in the straining friction coefficient and increased the wettability of the complex-shaped 3D-printed products. Full article

The glial tube is a longitudinal structure predominantly composed of densely bundled, aligned astrocytes that projects from the subventricular zone (SVZ) to the olfactory bulb. Neural precursor cells (NPCs) generated in the SVZ migrate through this glial tube—referred to as the rostral migratory stream (RMS)—to replace olfactory bulb interneurons in the mammalian brain. RMS astrocytes have distinct morphological and functional characteristics. These characteristics facilitate the unique purpose of the RMS as an endogenous living scaffold directing NPC migration and maturation. However, the transcriptomic factors underlying these unique structure–function attributes versus standard stellate astrocytes have not been examined. We previously developed biofabrication techniques to create the first tissue-engineered rostral migratory stream (TE-RMS) that replicates key features of the glial tube in vivo. We have shown that TE-RMS astrocytes exhibit elongated nuclei, longitudinally aligned intermediate filaments, and enrichment of key functional proteins—cytoarchitectural and surface features characteristic of native RMS astrocytes. In the current study, we performed RNA-seq on TE-RMS astrocytes in comparison to planar astrocyte cultures to identify gene expression patterns that may underlie their profound morphological and functional differences. Remarkably, we found 4,008 differentially expressed genes in TE-RMS astrocytes, with 2076 downregulated (e.g., LOC690251 and ccn5) and 1932 upregulated (e.g., lrrc45 and cntn1) compared to planar astrocytes. Moreover, there were 256 downregulated and 91 upregulated genes with >3-fold change. We also conducted analyses of gene sets related to cytoskeleton and nuclear structure, revealing the greatest enrichment of actin-related components. Overall, the TE-RMS offers a platform to study the interplay between transcriptomic and cytoarchitectural dynamics in a unique astrocyte population. Full article

This study proposes and demonstrates a highly sensitive displacement sensor based on a flexible random laser. The sensor utilizes a polydimethylsiloxane (PDMS) film where a self-assembled surface grating structure is formed via oxygen plasma surface treatment combined with bending prestress. This structure acts as a photon-trapping microcavity and multiple scattering feedback center, integrated with embedded laser dye PM597 as the gain medium to form a flexible grating random laser. Experiments show that the device generates random lasing emission under 532 nm pumping (threshold ~21 mJ/cm²) with a linewidth of ~0.25 nm and a degree of polarization of ~0.82. Applying micro-displacement alters the PDMS film curvature, subsequently changing the grating morphology (height, angle). This modifies photon trapping efficiency and geometric deflection loss within the equivalent resonator cavity, leading to significant modulation of the random laser output intensity. A linear correspondence between displacement and lasing intensity was established (R² ≈ 0.91), successfully demonstrating displacement sensing functionality. This scheme not only provides a low-cost method for fabricating flexible grating random lasers but also leverages the extreme sensitivity of random lasing modes to local disordered structural changes, paving the way for novel high-sensitivity mechanical sensors and on-chip integrated photonic devices. Full article

The aim of this research was to examine the antibacterial activity of commercially available silver nanoparticles against foodborne bacteria and to evaluate the properties of pullulan films incorporating these nanoparticles, including their antibacterial activity and selected physical properties. First, the antibacterial activity of silver nanoparticles against foodborne bacteria was investigated. The following parameters were assessed to evaluate the antibacterial activity of silver nanoparticles: minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), percentage antibacterial activity, bacterial survival based on time–kill curves, leakage of DNA and intracellular proteins using spectrophotometric measurements, and changes in bacterial cell morphology using scanning and transmission electron microscopy (SEM and TEM). Pullulan films with silver nanoparticle content ranging from 2 to 32 µg/cm² were obtained. The films were evaluated for antibacterial activity and physical properties, including macroscopic and microstructural (SEM) observations, thickness, light barrier, and color. Silver nanoparticles at a concentration of 25 µg/mL achieved 100% inhibition of the test bacteria, with destruction of bacterial cells after 3 or 6 h of incubation, depending on the silver nanoparticle concentration. Incorporation of silver nanoparticles into pullulan films, even in lower amounts, resulted in an antibacterial effect. All films had a compact and uniform microstructure and were shiny and flexible. Analysis of variance showed a significant (p < 0.05) effect of the addition of silver nanoparticles on the thickness, transparency, and color of the films. The obtained pullulan films containing silver nanoparticles were characterized by strong inhibitory activity against foodborne bacteria, had a brown color of varying intensity, a uniform microstructure, a smooth surface, and were barriers to UV radiation and visible light. Full article

Antarctica, largely free from geopolitical borders, serves as a critical site for scientific research, environmental monitoring and climate studies. The continent’s ice cap holds over 60% of the Earth’s freshwater and provides a stable climatological record spanning 800,000 years. In this study, the relationship between changes in atmospheric CO₂ levels over the past century and the microstructural characteristics of Antarctic ice was investigated. While it is well-documented that CO₂ fluctuations have driven the periodic expansion and retreat of ice sheets, no research to this day has explored how variations in CO₂ concentrations influence the physical integrity of ice at the microscopic scale. To address this, grain size, anisotropy, irregularity, and solidity of surface and near-surface ice samples collected over the past 70 years were analyzed. These microstructural features were compared against historical atmospheric greenhouse gas data from multiple Antarctic research stations, including records from the Scripps Institution of Oceanography, the Japanese Antarctic Research Expedition, and the NOAA Global Monitoring Laboratory. Results reveal a correlation between rising CO₂ levels and changes in ice microstructure, particularly an increase in the grain size as well as the reduction in the grain aspect ratio and in the morphological solidity. The study remains limited by significant sources of variability, including differences in sampling depths, geographical locations, seasonal effects, and inconsistencies in analytical tools and methodologies reported across the literature. Despite these limitations, this proof-of-concept study elicits the need for continued meta-analyses of existing climate datasets. Such efforts could provide deeper insights into the role of greenhouse gas concentrations in defining the microstructural stability of Antarctic ice, which is critical for predicting ice sheet integrity and its contribution to sea level rise. Full article

To investigate the contact performances and meshing characteristics of gears systematically, an improved comprehensive meshing stiffness model of spur gears with consideration of the tooth surface morphology, lubrication, friction, and thermal effects is presented based on the thermal elastohydrodynamic lubrication (TEHL) theory. The fractal feature of the tooth surface morphology is verified experimentally and characterized by the Weierstrass–Mandelbrot fractal function. Based on this, the rough contact stiffness, oil film stiffness, and thermal stiffness are introduced into the stiffness model. Comparisons between smooth and rough models are carried out, and the maximum temperature rise is increased by 24.7%. Subsequently, the influences of the torque, rotational speed, and fractal parameters on the oil film pressure and thickness, friction and temperature rise, and contact stiffness and comprehensive meshing stiffness are investigated. The results show that the oil film pressure and the maximum temperature rise increase by 125.18% and 69.08%, respectively, with an increasing torque from 20 N·m to 300 N·m. As the rotational speed is increased, the oil film thickness sharply increases, the rough peak contact area and friction reduce, and the stiffness fluctuation weakens. For fractal parameters, the oil film pressure and film thickness, friction, and temperature rise are nonlinear with changes in the fractal dimension D and fractal scale characteristic G. The results reveal that this work provides a more reasonable analysis for understanding the meshing characteristics and the design and processing of gears. Full article

Pinus yunnanensis, is an ecologically and economically important tree species in southwestern China. However, its natural renewal is relatively lagging behind, and it is difficult to achieve sustainable development. Apical removal (top-pruning) can eliminate apical dominance, stimulate sprouting, and provide high-quality scions for clonal propagation. Root systems are a critical foundation for sprouting capacity. In this study, one-year-old P. yunnanensis seedlings were subjected to four treatments: removal of 3/4 (H1), 2/4 (H2), or 1/4 (H3) of the seedling height, and a non-topped control group (CK). The objective was to investigate the seedlings’ responses in terms of root morphology, biomass allocation, and allometric growth. The results showed that by May, biomass allocation in the topped treatments increased by 13.37%, 11.01%, and 7.86%, respectively, compared with the control, and also exhibited higher coefficients of variation. Under the H2 treatment, both fine and coarse roots accounted for a higher proportion of total root biomass and displayed stronger water-retention stability. With increased top-pruning intensity and time, root volume, specific root length, root tissue density, and root tip number were the first to respond, indicating the onset of allometric growth. Notably, in May, the growth rate of specific root surface area followed the order: H3 > H1 > CK > H2. These findings suggest that the root system adapts to environmental changes by modulating growth patterns among various indicators to optimize resource allocation and enhance adaptability. Full article

This study focuses on the susceptibility and surface degradation of low-alloy carbon steel 42CrMo4 to corrosion and cavitation erosion, as this steel is widely used in marine environments with aggressive chemical species and harsh conditions. Due to its high strength and fatigue resistance, 42CrMo4 steel is often employed in offshore mechanical components such as shafts and fasteners as well as crane parts in ports and harbors. Various experimental methods, including corrosion and cavitation tests, were used to assess the steel’s surface integrity under extreme conditions. Surface changes were monitored using modern analytical tools for precise assessments, including image and morphological analyses, to quantify degradation levels and specific parameters of defects induced by corrosion and cavitation. Non-destructive techniques such as optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and image analysis software were employed for the quantitative assessment of morphological parameters and elemental analysis. EDS analysis revealed changes in elemental composition, indicating corrosion products that caused significant mass loss and defect formation, with degradation increasing over time. The average corrosion rate of 42CrMo4 steel in a 3.5% NaCl solution reached a peak value of 0.846 mm/year after 120 days of exposure. Cavitation erosion behavior was measured based on mass loss, indicating the occurrence of different cavitation periods, with the steady-state period achieved after 60 min. The number of formed pits increased until 120 min, after which it decreased slightly. This indicates that a time frame of 120 min was identified as significant for changes in the mechanism of pit formation. Specifically, up to 120 min, pit formation was the dominant mechanism of cavitation erosion, while after that, as the number of pits slightly declined, the growth and merging of formed pits became the dominant mechanism. The cavitation erosion tests showed mass loss and mechanical damage, characterized by the formation of pits and cavities. The findings indicate that the levels of surface degradation were higher for corrosion than for cavitation. The presented approach also provides an assessment of the degradation mechanisms of 42CrMo4 steel exposed to corrosive and cavitation conditions. Full article

This paper presents the growth and in situ optical characterization of silicon nanowires (Si NWs) on Al₂O₃(0001) substrates that are thermally faceted using the atomic low angle shadowing technique (ATLAS) method. Annealing Al₂O₃ substrates in air before surface faceting was used for the first time, as identified by atomic force microscopy (AFM). Planar Si NW arrays were subsequently deposited and characterized in real-time by reflectance anisotropy spectroscopy (RAS). RAS measurements detected irreversible spectral changes during growth, e.g., red-shift in peak energy for marking amorphous Si NW formation. Blue-shifts in RAS spectra following annealing post-growth at varied temperatures were found to be associated with structural nanowire development. AFM analysis following annealing detected dramatic changes in morphology, e.g., quantifiable differences in NW height and thickness and complete disappearance of nanowire structures at high temperatures. These results confirm the validity of in situ RAS as a monitoring tool for nanowire growth and illustrate Si NW morphology’s sensitivity to thermal processing. Full article

The intensification of thermal stress in cities due to urbanization and climate change underscores the urgent need to improve outdoor habitability. This study analyses the influence of three opaque façade technologies—traditional, lightweight and external thermal insulation composite systems—combined with two albedo levels (0.30 and 0.80), on summer outdoor conditions in Mendoza (Argentina), Madrid (Spain) and Campinas (Brazil). Using a calibrated microclimatic model with ENVI-met v5.6 software, a digital replica of a 10-storey urban canyon was simulated to generate 18 scenarios, assessing the effect of façade thermal mass and reflectivity on the urban microclimate. The results show that (i) scenarios that mainly affect air temperature (AT) are those that modify the thermal mass of the façade technologies. For example, traditional technology with a low albedo reduce maximum AT by up to 1.2 °C in Campinas, 0.89 °C in Mendoza, and 0.81 °C in Madrid compared to light technology with the same albedo level. (ii) Mean radiant temperature (MRT) increases significantly in scenarios involving lightweight façade by 4.53 °C in Madrid, 4.46 °C in Mendoza, and 3.39 °C in Campinas. Conversely, increasing façade albedo further amplifies MRT due to multiple reflections in urban canyons with increases of 6.50 °C in Campinas, 6.09 °C in Mendoza, and 5.33 °C in Madrid. The impact is more pronounced with traditional façades. (iii) Traditional façades and low-albedo ETIC systems experience the fewest hours of very high thermal stress (UTCI > 38 °C), whereas lightweight façades increase exposure to extreme heat. Overall, air temperature is primarily determined by façade thermal mass, mean radiant temperature by surface reflectivity, and thermal comfort by the combined effect of both. These findings confirm that high reflectivity can be counterproductive in dense urban canyons, emphasizing the importance of climate- and morphology-sensitive façade strategies for urban resilience. Full article

Regulated proteolysis via autophagy is essential for cellular homeostasis, yet the specific role of autophagy-related gene 7 (ATG7) in corneal epithelial maintenance remains unclear. Using a conditional knockout mouse model (Atg7^f/f K14Cre^+/−), we investigated the impact of ATG7 deficiency on corneal epithelial autophagy, morphology, and vascular dynamics. Loss of ATG7 disrupted autophagosome formation, evidenced by increased LC3B expression but reduced LC3B-positive puncta and absence of autophagosomes ultrastructurally. Although gross corneal morphology was preserved, ATG7 deficiency led to thickened epithelium and increased peripheral lymphatic vessel sprouting, indicating a pro-inflammatory and pro-lymphangiogenic microenvironment. Proteomic analysis revealed upregulation of RAB8, TM9S3, and RETR3, suggesting activation of compensatory pathways such as exophagy, reticulophagy, and Golgiphagy. Inflammatory and angiogenic components were downregulated, suggesting a moderate loss of inhibitory capacity based on the lymphatic phenotypes observed. At the same time, while these two compensatory changes occur, other proteins that positively regulate lysosome formation are reduced, resulting in a phenotype linked to deficient autophagy. These findings demonstrate that ATG7-mediated autophagy maintains corneal epithelial homeostasis and immune privilege, with implications for understanding corneal inflammation and lymphangiogenesis in ocular surface diseases. Full article

In this study, the effects of batch and continuous grinding on the ceramic floor tile body were investigated in terms of cost, capacity, and technical aspects. In batch milling, a changing speed during grinding was more efficient than a constant speed. Capacity and energy consumption increased as the mill rotation speed increased in continuous grinding. Specific energy consumptions were measured as 36 kW/ton and 43.1 kW/ton, with 1.6 ton/h and 8.375 t/h capacities. Additionally, d₁₀, d₅₀, and d₉₀ values for ground ceramic floor tile bodies were determined to be 2.5, 9.5, and 47.2 µm and 2.5, 9.4, and 48.1 µm for batch and continuous grinding, respectively. No significant difference was observed in the color and shrinkage values, while water absorptions were calculated to be 1.1% and 0.3% as sintering properties for batch and continuous methods, respectively. In the phase analysis of a sintered body prepared using the continuous method, mullite and quartz were observed, while microcline was also analyzed differently from such minerals for the batch one. Structural changes, surface morphology, and roughness were also interpreted by DTA/TG, SEM, and AFM analysis. The presence of plastic clay minerals during the grinding process in batch milling caused non-plastic raw materials not to be ground sufficiently, and sintering characteristics changed. Full article

Electric arc furnace (EAF) waste, a mixture of dust and slag, was investigated as a potential secondary source of zinc. The waste primarily consisted of zinc and iron oxides, with the presence of refractory zinc ferrite, which hinders the complete recovery of zinc. This is the first study that examined the effect of mechanical treatment through high-energy planetary ball milling on the phase transformation, metal speciation, and leachability of the EAF waste. The raw material was characterized by particle size distribution, morphology, phase composition, and sequential extraction, and then subjected to milling at different rotation rates (100–400 rpm). The resulting powders were analyzed using XRD, SEM–EDS, and sequential leaching, and tested for acid (H₂SO₄) and alkaline (NaOH) leachability. Milling progressively reduced particle size, increased surface roughness, and induced structural changes, including the mechanical activation effect at low milling rates (100 rpm) and the synthesis of secondary franklinite at higher milling energies (200 rpm and 400 rpm). Sequential extraction revealed changes in zinc and iron speciation from acid-soluble to residual fractions for increased milling intensities. Leaching experiments showed rapid zinc dissolution in both acidic and alkaline solutions, while iron dissolved only in acid. The highest zinc extractions (67% in H₂SO₄, 55% in NaOH) were obtained from mechanically activated material at 100 rpm, while zinc leachability decreased for higher milling rates due to the induced mechanical synthesis of refractory phase. The kinetic model of leaching of the main components of the EAF was also established. Full article

Beaches are important geomorphic units shaped by land–sea interactions. Changes in their profiles and surface sediments are directly influenced by both natural processes and human activities. This study is based on continuous topographic and sediment monitoring from 2021 to 2023 on the open and sheltered beaches of Puqian Bay, Hainan Island. It investigates the interannual profile evolution and the spatiotemporal response of sediment grain size under the influence of an artificial island. The results show that the Guilinyang Beach profile is mainly characterized by seasonal erosion–accretion cycles and the seaward migration of sandbars, while the Hilton Beach profile has undergone long-term erosion. At Hilton, sediment grain size changes are strongly coupled with profile erosion and accretion. Seasonal waves drive spatial differences in both profile and grain-size variation across Puqian Bay. The artificial island has reshaped local alongshore sediment transport and wave energy distribution. This has led to continuous erosion and coarsening in the open sector, while the sheltered sector remains morphologically stable. These findings reveal the spatiotemporal response patterns of headland-bay beaches under both natural and anthropogenic forcing, and provide scientific evidence for understanding coastal sediment dynamics and the impacts of artificial structures. Full article

The dynamic behavior and biologically mediated transformation of microplastics (MPs) in crustaceans remain insufficiently explored in aquatic ecotoxicology. In this study, we employed the red swamp crayfish (Procambarus clarkii) as a model organism to systematically investigate the accumulation, distribution, fragmentation, and excretion kinetics of MPs within its digestive system under controlled conditions. We exposed crayfish to fluorescent polystyrene microplastics (50 μm) at a high concentration (100,000 particles/L), which exceeded typical environmental levels but was necessary to track accumulation and fragmentation dynamics within the experimental timeframe, and dissections were performed at 24, 48, and 96 h. Spatiotemporal patterns and morphological changes in MPs were analyzed using advanced microscopic imaging techniques. The results revealed a peak in MP accumulation at 48 h, followed by a decrease at 96 h, suggesting a dynamic equilibrium between ingestion and elimination. Over time, particle sizes decreased significantly, a result consistent with microplastic fragmentation. Additionally, feed supplementation during depuration was associated with increased fragmentation efficiency. Morphological analysis showed digestion-induced changes such as surface wrinkling, irregular edges, and particle shrinkage. These findings elucidate the transformation mechanisms of microplastics within crustaceans and provide crucial insights for assessing their potential ecological risks and fate as pollutants. Based on results from high-concentration short-term laboratory exposure studies, this paper further indicates the necessity for in-depth exploration into the long-term dynamics of microplastics within aquatic organisms and the potential for their transfer across trophic levels. Full article