Search Results (1,052)

Bio-epoxy composites were fabricated by casting a resin–hardener–filler mixture into 3D-printed molds, using different sea-originated secondary raw materials: mussel shell powder (MSP) (63–83 μm) and Posidonia oceanica short fibers (POF) (1–2 mm). Monofiller composites were prepared with 5 or 10 wt.% MSP, or 5 or 10 wt.% POF. Hybrid formulations were also produced, containing both MSP and POF in two combinations, where the total amount of filler again summed up at 10 wt.%. A subset of the samples was conditioned by immersion in a 35 ‰ NaCl solution reproducing seawater composition until saturation was reached. Characterization was carried out on unconditioned and conditioned samples by Shore D hardness and Charpy impact tests while performing three-point flexural loading only on unconditioned ones. Fracture morphology was also investigated. Adding MSP slightly enhanced resin hardness, whereas impact absorption exhibited, to a variable extent, a two-phase behavior, reproducing crack initiation and propagation. The MSP6-POF4 hybrid configuration provided the greatest improvement in absorbed energy (25–30% higher), which was retained after conditioning. The introduction of fillers, first separately, then in combination, resulted in a reduction in flexural strength to a similar extent for all unconditioned configurations. Finally, composite panels containing 10 wt.% MSP, 10 wt.% POF, and a 6MSP–4POF hybrid formulation, intended for prospective boat deck applications, were fabricated and compared with neat bio-epoxy, showing satisfactory consolidation. Density and post-molding dimensional shrinkage were measured on the panels. Full article

Stress evolution during overburden stabilization in non-pillar mining with roof-cutting and roadway formation (NMRRF) in inclined coal seams is highly complex due to the combined influence of seam dip angle and mining method. This study investigates the spatial stress evolution and structural stability of the overburden through numerical simulation and theoretical analysis. Results indicate that along the strike direction, the peak abutment pressure ahead of the working face decreases from the lower to the upper sections. As mining advances, the peak in the lower section shifts significantly forward, whereas changes in the middle and upper sections remain minimal. After advancing 150 m, upward expansion of the pressure-relief zone ceases, with the relief height in the lower goaf being smaller than that in the upper region. Along the dip direction, a pressure-relief zone forms in the roof and floor after 30 m of advancement, while stress concentration zones develop in the coal on both sides. With continued mining, the highest point of the pressure-relief zone gradually deviates from the central axis toward the upper section and eventually stabilizes within deeper strata at a certain distance from the axis. By 150 m of advancement, the relief zone peaks in the upper-middle section of the working face, and the height of the caved zone in the upper goaf exceeds that in the middle and lower parts. An asymmetric “inverted J-shaped” stress shell forms along the working face centerline, evolving into an overall asymmetric stress shell with its apex located in the upper goaf. A mechanical model of the overburden structure is established, yielding an expression for the three-dimensional stress shell morphology. Based on the stability mechanism of overburden movement and the failure modes of key block structures, support strategies for the mining face are proposed. The findings provide theoretical insights for non-pillar mining under similar geological conditions. Full article

Melanoides tuberculata is one of the world’s main invasive snail species; therefore, mapping its occurrence is essential for predicting its dispersion patterns and proposing control measures. This study aimed to map the occurrence of M. tuberculata and its associated parasites in a tourist waterfall complex located in Fortaleza dos Nogueiras, Southern Maranhão, Brazil. We collected snails over three months (July, August, and September 2025) in the Castanhão, Esmeralda, and Recanto das Águias waterfalls, and in the Panela stream, to estimate their reproductive stage and to assess the presence of parasites. We demonstrated for the first time the occurrence of M. tuberculata at all evaluated collection points. Morphological data of the shells suggested that the M. tuberculata populations were in the initial phase of their reproductive cycle; however, some specimens showed a complete reproductive stage. Additionally, we found M. tuberculata infected with trematode larvae that resembled the Gymnocephalus-type cercariae in the Castanhão waterfall and Panela stream. Therefore, we updated the distribution of M. tuberculata in Brazil and discussed the possible environmental and public health impacts of this species in the study area. Full article

Hypo-peritectic steels are susceptible to interfacial cracking during thin-slab continuous casting, in which non-metallic inclusions play a critical role. This study systematically investigates the effects of inclusion type and morphology on interface cracking behavior in the steel matrix, with the aim of improving billet shell quality. Hot tensile experiments were conducted using a Gleeble 3800 thermal simulator, and a finite element–based cohesive zone model was developed to simulate inclusion-induced crack nucleation and propagation. The results demonstrate that inclusions markedly influence interfacial stress distribution and damage evolution. The maximum interfacial stresses associated with MnS, Al₂O₃, and composite inclusions are 20.7, 23.4, and 30.5 MPa, respectively. Owing to severe stress concentration at sharp corners, composite inclusions exhibit the earliest crack nucleation at an applied stress of 11.3 MPa and the highest energy dissipation. In all cases, cracks initially nucleate at the location of maximum tensile stress (α = 90°), propagate along the interface, and subsequently penetrate into the matrix, ultimately leading to failure. The strong agreement between numerical simulations and experimental results confirms that angular inclusions accelerate damage by disrupting matrix continuity. These findings provide theoretical guidance for improving hypo-peritectic steel quality through inclusion morphology control during continuous casting. Full article

Plasmon-driven surface catalysis has attracted significant interest due to its capacity to integrate near-field enhancement and hot-carrier effects at the nanoscale synergistically. In this work, nanoporous Au-Ag shells (NPASs) were prepared via a galvanic replacement process. The coupling of p-nitrothiophenol (PNTP) to form 4,4′-dimercaptoazobenzene (DMAB) was used as a model reaction to evaluate plasmonic catalytic kinetics on three substrates, including NPASs, Au nanoparticles (Au NPs), and Ag nanoparticles (Ag NPs), under 532 and 633 nm excitation. TEM, XRD, EDX, and HAADF-STEM analyses confirmed that the NPASs exhibited a hollow nanoporous morphology and a homogeneous Au-Ag alloy structure. UV-Vis extinction spectroscopy revealed a broadband response in the visible region, with a main peak at ~683 nm and a shoulder at ~542 nm. Based on in situ time-resolved SERS monitoring and first-order kinetic fitting, all three substrates showed faster conversion rates under 532 nm excitation. To quantitatively assess wavelength selectivity, a wavelength-dependent factor (R = k₅₃₂/k₆₃₃) was introduced. Quantitative analysis demonstrated that Au NPs exhibited the most significant R value (15.0), followed by Ag NPs (2.3), whereas NPASs exhibited the smallest R value (1.7). This distinct difference indicated that the wavelength selectivity of monometallic Au NPs was primarily governed by the resonant matching between the LSPR and the incident wavelength. In contrast, the broadband extinction of NPASs enabled strong optical responses at both wavelengths, resulting in a significantly weaker wavelength dependence. This work provides essential experimental evidence for designing plasmonic catalytic substrates with improved wavelength adaptability. Full article

This study focuses on fabrication and comprehensive characterization of gold nanoparticles (AuNPs) stabilized with polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG), correlating polymer degradation with colloidal stability and localized surface plasmon resonance (LSPR) behavior under controlled gamma doses from 5 to 125 Gy. AuNPs were synthesized via laser-assisted synthesis (LAS) in aqueous medium containing PVP or PEG as a stabilizing and capping agent. Morphology, size distribution, and surface functionalization of the resulting AuNPs@polymer-stabilized were verified through UV-Vis spectroscopy, FTIR, XRD, DLS, zeta potential, and TEM. Results show that the polymer shell effectively preserved the nanoparticles’ integrity by minimizing aggregation and maintaining LSPR features even after exposure to high gamma doses (>75 Gy). PVP demonstrated superior protection compared to PEG, due to the robustness of the solvation layer and carbonyl groups of PVP coating around the AuNPs. These findings highlight the potential of polymer-stabilized AuNPS for applications in radiation-rich environments, while demonstrating LAS as an environmentally friendly and efficient synthesis route. Full article

Aligned with circular bioeconomy principles, which aim to establish closed-loop systems that maximize resource utilization and renewal while minimizing waste, this study developed and characterized innovative catalysts derived from waste almond shells. These shells were carbonized and functionalized to create active surfaces containing Lewis and Brønsted acid sites. Modification was achieved through treatment with ZnCl₂ to introduce Lewis acid (LA) sites and with sulfuric acid to generate Brønsted acid (BA) sites. Detailed instrumental analyses enabled assessment of catalyst morphology, textural parameters, and surface functional groups. A physical mixture of the two catalysts was used to convert glucose into 5-hydroxymethylfurfural (HMF), yielding a maximum HMF yield of 76.8%. The results indicate that the collaborative action of Lewis and Brønsted acid sites, along with oxygen-containing surface groups, contributes to catalyst efficiency. These insights facilitate targeted catalyst optimization by adjusting surface texture and functional groups. Full article

This study examined the effects of hydrodynamic conditions on the growth performance and nutritional quality of Pacific oysters (Crassostrea gigas) in raceway flumes. Oysters were reared under three flow velocities—low (LV, 5 cm/s), medium (MV, 10 cm/s), and high (HV, 20 cm/s)—using three replicate flumes per treatment, each containing 100 individuals. Results indicated that while shell morphology remained unaffected by flow rate, MV significantly enhanced soft tissue weight and meat yield compared to LV. Physiologically, HV upregulated the activities of trypsin and amylase, with trypsin levels significantly exceeding those in LV. Furthermore, MV exhibited the highest crude protein and glycogen content. Notably, both MV and HV improved the accumulation of total and essential amino acids. Fatty acid profiles showed clear separation among treatments, primarily driven by C16:0, C18:0, C20:5n3, C22:1n9, and C20:2. Collectively, moderate flow velocity (10 cm/s, MV) resulted in a well-balanced enhancement of growth, biochemical composition, and nutritional value compared to low or high velocities, highlighting the potential value of controlled hydrodynamic conditions in oyster farming. Full article

During the transportation of oil and gas pipelines, the adhesion and aggregation of hydrate particles on the pipe wall are prone to cause pipeline blockage, which seriously impairs the safe and efficient transportation of energy. Taking cyclopentane hydrates as the research object, this study investigated the effects of contact time, wall wettability, and the concentration of kinetic hydrate inhibitor poly(N-vinylcaprolactam) (PVCap) on the adhesion force between hydrates and the wall of X80 pipeline steel by combining a high-precision micromechanical force measurement system with microscopic morphology observation and analysis. The results show that the adhesion force increases with prolonged contact time: it is dominated by capillary liquid bridge force in the initial contact stage with slow growth, and after exceeding the critical time, the sintering effect becomes the dominant factor, leading to a rapid rise in adhesion force that eventually tends to stabilize. Wall wettability significantly influences the adhesion force, and enhanced wettability improves the adhesion force by increasing the liquid bridge volume and the hydrate–wall contact area. PVCap concentration exerts a non-monotonic effect on adhesion force—first decreasing and then increasing. At low concentrations (0.25–1 wt%), PVCap molecules adsorb on the hydrate surface to form a physical barrier, reducing adhesion force. At high concentrations (1.5–2 wt%), excessive PVCap damages hydrate shell integrity, releasing free water to expand the liquid bridge volume and increase adhesion force. This study provides a theoretical basis for eliminating or reducing hydrate blockage in deep-sea oil and gas pipelines. Full article

Flame-retardant microcapsules were prepared using a urea–melamine–formaldehyde (UMF) shell and boric acid-crosslinked ammonium polyphosphate (APP) as the core to improve the dispersion stability and processing compatibility of phosphorus-based flame retardants. Thermal analysis showed that the microcapsules exhibited initial mass loss near 80 °C due to moisture evaporation and shell relaxation, while APP-related degradation occurred at higher temperatures, indicating delayed release of the core and enhanced thermal resistance through encapsulation. Scanning electron microscopy confirmed the formation of microcapsules, and morphological changes before and after combustion suggested the development of protective char layers. Boron-containing residues are expected to contribute to char stabilization through the formation of B–O–P structures during heating. The flame-retardant properties were evaluated using limiting oxygen index, smoke density, and vertical burning tests. Although the limiting oxygen index slightly decreased due to reduced accessible APP content, stable burning behavior was maintained, and characteristic char formation was observed after combustion. These results indicate that the UMF/APP microcapsules can improve thermal stability and handling of phosphorus-based flame retardants. The microencapsulation approach presented here may provide practical advantages for polymer processing and surface-coating applications. Full article

Mactra antiquata sensu lato, a commercially important clam species in China, exhibits remarkable morphological and molecular diversity, which has led to the proposal of cryptic species within this complex. In the present study, specimens of M. antiquata sensu lato were collected from four coastal provinces (Shandong, Guangdong, Guangxi, and Hainan) of China, and an integrated comparative analysis was performed based on morphological traits and partial sequences of two mitochondrial genes (cytochrome c oxidase subunit I, COI; and 16S rRNA). Our results revealed that M. antiquata sensu lato could be clearly delineated into two distinct clades: the N-group (comprising specimens collected from Shandong in this study) and the S-group (including specimens collected from Guangdong, Guangxi, and Hainan), with significant intergroup differences. Morphologically, S-group individuals possessed relatively narrower shells (mean shell width-to-length ratio = 0.465) and shorter shells (mean shell height-to-length ratio = 0.781) compared to N-group conspecifics. Additionally, the pallial sinus of S-group clams extended directly toward the anterior adductor muscle, whereas that of N-group clams pointed to the region below the anterior adductor muscle. Furthermore, the escutcheon of N-group individuals was considerably more slender than that of the S-group. Phylogenetic trees and haplotype networks constructed based on both partial COI and 16S rRNA sequences further confirmed a deep genetic divergence between the two groups, with Kimura 2-parameter distances of 0.158 for COI and 0.084 for 16S rRNA. Collectively, these morphological and molecular lines of evidence strongly support the existence of cryptic species within M. antiquata sensu lato. By comparing the morphological characteristics of specimens in this study with the original description of M. antiquata, we herein propose that the S-group represents a new species, which we named M. haiboensis sp. nov. Our findings provide a scientific basis for the targeted conservation and further research of both M. antiquata and M. haiboensis sp. nov. Full article

Silica nanoparticles (SNPs) are pivotal in designing functional optical films, but accurately modeling their properties is hindered by the limitations of classical effective medium theories, which break down for larger particles and complex morphologies. We introduce a robust, effective medium theory that overcomes these limitations by incorporating full Mie scattering solutions, thereby accounting for size-dependent and multipolar effects. Our model is comprehensively developed for unshelled, shelled, mixed, and hollow SNPs randomly dispersed in a host medium. Its accuracy is rigorously benchmarked against 3D finite-element method simulations. This work establishes a practical and reliable framework for predicting the optical response of SNP composites, significantly facilitating the rational design of high-performance coatings, such as anti-glare layers, with minimal computational cost. Full article

Root restriction is an agronomic technique that influences plant morphology, physiology, and productivity. This study investigates the effects of root restriction on tomato growth, fruit quality, yield, and rhizosphere microbial communities using three distinct substrates: sand, soil, and peanut shell substrate (PSS), within a Simplified Automatic Soilless Culture System (SAS). Results demonstrated that root restriction at 8 cm height significantly enhanced fruit quality indicators: soluble sugar content increased by 69.01% (sand), 53.84% (soil), and 37.67% (PSS); soluble protein increased by 77.23%, 48.14%, and 66.51%; and lycopene increased by 100.03%, 62.33%, and 74.59%, respectively, compared to the 24 cm baseline. However, single-plant yield declined by 28.30% (sand), 64.28% (soil), and 22.06% (PSS). TOPSIS analysis (Technique for Order Preference by Similarity to Ideal Solution) identified PSS at 8 cm as the optimal combination for balancing quality and yield (Cj = 0.631). Microbial amplicon sequencing revealed higher rhizosphere microbial diversity in tomatoes grown in soil and peanut shell substrate compared to sand. These three types of growing media (soil, sand, and peanut shell substrate) establish the rhizosphere of bacterial and fungal communities by selecting specific microbial taxa. Changes in container height drive the reduction–oxidation functional divergence of bacterial communities, affecting the connectivity and complexity of microbial networks. Full article

Ascaris lumbricoides is one of the most epidemiologically significant soil-transmitted helminths, and the environmental persistence of its eggs is largely attributed to their robust structural architecture. The search for ovicidal alternatives capable of overcoming this barrier has increasingly focused on metallic nanoparticles obtained through biological synthesis. Scanning electron microscopy (SEM) was employed to evaluate the ultrastructural effects of silver nanoparticles (AgNPs) biosynthesised by the nematophagous fungus Duddingtonia flagrans on A. lumbricoides eggs. Ultraviolet-visible spectroscopy and transmission electron microscopy confirmed the synthesis of AgNPs, revealing predominantly spherical, well-dispersed particles with an average diameter of 9.22 ± 4.9 nm. Cytotoxicity assays indicated an IC₅₀ of 7.7 µg/mL. SEM analyses showed that eggs in the control group maintained intact morphology, with no apparent deformities. In contrast, exposure to AgNPs induced pronounced structural alterations, including marked wrinkling, surface erosion and shell collapse, suggesting disruption of multiple layers. Albendazole alone produced deep linear fissures consistent with internal metabolic failure, though with minimal external erosion. The combined treatment with AgNPs and albendazole resulted in severe degradation. These findings demonstrate that AgNPs exhibit significant ovicidal activity and may serve as effective adjuvants to enhance the action of conventional anthelmintics against highly resistant helminth eggs. Full article

Sharp declines in temperature pose a significant risk for mass mortality events in the Chinese soft-shelled turtle (Pelodiscus sinensis). To assess the effects of acute cold stress on intestinal health, turtles were exposed to temperatures of 28 °C (control), 14 °C, and 7 °C for 1, 2, 4, 8, and 16 days. The results showed that acute cold stress at 14 °C and 7 °C induced time-dependent alterations in intestinal morphology and histopathology. The damage was more severe at 7 °C, characterized by inflammatory cell infiltration, lymphoid hyperplasia, and extensive detachment and necrosis across the villi, muscle layer, and submucosa. 16S rDNA sequencing revealed significant shifts in intestinal microbiota composition in the 7 °C group, dominated by Helicobacter and Citrobacter. Transcriptomic analysis identified differentially expressed genes (DEGs) that respond to acute cold stress and are involved in the Toll-like receptor signaling pathway (Tlr2, Tlr4, Tlr5, Tlr7, and Tlr8), the NOD-like receptor signaling pathway (Traf6, Traf2, Casr, Rnasel, Pstpip1, Plcb2, Atg5, and Mfn2), apoptosis (Tuba1c, Ctsz, Ctsb, Kras, Hras, Pik3ca, Bcl2l11, Gadd45a, Pmaip1, Ddit3, and Fos), and the p53 signaling pathway (Serpine1, Sesn2, Ccng2, Igf1, Mdm2, Gadd45a, Pmaip1, and Cdkn1a). Metabolomic profiling highlighted differentially expressed metabolites (DEMs) that cope with acute cold stress, such as organic acids (oxoglutaric acid, L-aspartic acid, fumaric acid, DL-malic acid, and citric acid) and amino acids (including L-lysine, L-homoserine, and allysine). The integrated analysis of DEGs and DEMs underscored three key pathways modulated by acute cold stress: linoleic acid metabolism, neuroactive ligand–receptor interaction, and the FoxO signaling pathway. This study provides a comprehensive evaluation of intestinal health in Chinese soft-shelled turtles under acute cold stress and elucidates the underlying mechanisms. Full article