Search Results (1,938)

Hydrothermal activity plays a critical role in ancient oceanic environments, organic matter accumulation, and metallic ore deposit formation. During the Early Cambrian, the development of hydrothermal systems in the southern Anhui Province of the Lower Yangtze Block has long attracted geological attention. This study focuses on the Lower Cambrian black shales of the Hongtaocun (HTC) section in the southern Anhui Province, employing major- and trace-element analyses, rare earth element (REE) geochemistry, and field-emission scanning electron microscopy (FE-SEM) observations to identify evidence for Early Cambrian hydrothermal activity on the Yangtze Platform and its controls on mineralization. Our results demonstrate that major-element proxies classify the HTC samples as biogenic, but this classification is demonstrably incorrect given the mineralogical and REE evidence, which highlights the limitations of major-element discrimination alone. Hyalophane (Hy) occurrence records Ba-rich hydrothermal fluids, while positive Eu anomalies in the REE patterns further corroborate hydrothermal influence. We, therefore, emphasize that major-element chemistry alone is insufficient to reliably identify hydrothermal processes. These findings substantially advance the discrimination criteria for ancient seafloor hydrothermal activity. Full article

Epoxy resins are widely used thermosetting polymers, but their limited toughness and flexural resilience restrict broader applications. In this study, diglycidyl ether of bisphenol A (DGEBA) epoxy was reinforced with 5 wt.% ceramic fillers of different origins: sol–gel alumina calcined at 550 °C (γ-Al₂O₃) and 1000 °C (α-Al₂O₃), silica derived from rice husk, silica from diatomaceous earth, and a hybrid alumina–silica mixture prepared by sol–gel and calcined at 1000 °C. Fillers were structurally characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field-emission scanning electron microscopy (FESEM). Mechanical properties were evaluated through tensile (ASTM D638) and flexural (ASTM D790) testing. All reinforcements enhanced the performance of neat epoxy. γ-Al₂O₃ provided superior tensile reinforcement compared to α-Al₂O₃, underscoring the importance of particle morphology and surface reactivity. The hybrid alumina–silica filler achieved the highest flexural strength of 50.6 MPa, compared to 9.91 MPa for the neat epoxy. Bio-derived silica showed improved flexural properties, although its tensile reinforcement was less pronounced compared to the sol–gel derived fillers. These results establish clear structure–property relationships and confirm that filler phase, morphology, and calcination temperature critically govern the mechanical performance of epoxy composites. Full article

The performance of fluid solidified soil (FSS) depends on the curing agents as well as, to a great extent, the soil type. Currently, most studies focus on a single type of soil, which limits the applicability of research findings to practical engineering scenarios involving diverse soil conditions. To address this issue, this study selects two representative soil types—clay (CL) and silt (ML)—and employs alkali-activated red mud–slag as curing agent to prepare FSS. Laboratory experiments were conducted to evaluate the influence of soil type on the engineering properties and durability of the specimens. Specifically, the effects of soil type on flowability and unconfined compressive strength were comparatively analyzed. Durability was assessed through shrinkage, water stability and wet–dry cycle tests. Furthermore, X-ray diffraction, Thermogravimetric, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and Brunauer–Emmett–Teller were utilized to characterize the microstructure and hydration products of the samples. The results indicate that an increasing proportion of ML leads to a decrease in overall flowability but a significant enhancement in late-age unconfined compressive strength. Meanwhile, the drying shrinkage of ML is gradually reduced, and both water stability and resistance to wet–dry cycles are correspondingly improved. Microstructural analyses reveal that the primary hydration product across all samples is C-(A)-S-H gel. Samples with higher ML content exhibit a denser structure and an increased volume of hydration products, which is consistent with the observed macroscopic performance trends. Full article

X-band copper resonating cavities are key components of future pulsed GHz normal-conductive multi-TeV accelerators. High electric field gradients are required for emerging applications; however, as gradients increase, components’ lifetime decreases, primarily due to radiofrequency (RF) breakdown. Coating technologies are being investigated in several laboratories to improve RF structure, performance and lifetime. To this end, we investigated the feasibility of fabricating nanometer-periodic Cu/Mo metallic multilayers on three-dimensional (3D) aluminum mandrels designed to replicate X-band copper resonating cavities. These nanometer-period multilayers are proposed to mitigate surface degradation due to electric breakdown at high accelerating gradients by stabilizing inner cavity surfaces against dislocation evolution and roughening caused by thermo-mechanical fatigue. High-Power Impulse Magnetron Sputtering (HiPIMS) in a bias-controlled dual closed-field magnetron configuration was employed to deposit alternating Mo and Cu nano-layers onto the 3D geometries. Given the complexity of HiPIMS technology, plasma pulse evolution was studied by combining time-resolved optical emission spectroscopy with electrical measurements of the pulse discharge. The influence of the process parameters, particularly the applied DC bias, on film growth was studied using non-destructive microprobe α-particle elastic backscattering spectrometry (µEBS) and scanning transmission electron microscopy (STEM). STEM and µEBS analyses confirmed that Mo layers with thicknesses of approximately 5–35 nm were successfully deposited repeatedly on thicker Cu layers (30–150 nm), preserving individual layer properties with minimal interdiffusion and alloying. The layers were deposited inside trenches with an aspect ratio of 5:1 representative of X-band irises. This technology, coupled with the replica process, could be applied to highly engineered nanostructured coatings for X-band cavity treatment in compact particle accelerator prototypes, as it may improve electrical breakdown lifetime under high accelerating fields, at least for degradation processes driven by the high mobility of copper dislocations. Full article

This study investigated the effect of post-silanization processing on the surface chemistry and dispersion stability of 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) nanoparticles intended for the reinforcement of dental photopolymer resins. The nanoparticles were silanized using 3-Methacryloxypropyltrimethoxysilane and subjected to different post-treatment protocols, including control, drying, and centrifugation. Particle morphology was examined using field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Dispersion behavior was analyzed by dynamic light scattering (DLS) and zeta potential measurements, performed in triplicate (n = 3), while surface chemical modifications were evaluated using Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Post-silanization processing significantly influenced nanoparticle surface chemistry and dispersion stability. Centrifugation promoted the formation of Si–O–Zr and Si–O–Si linkages, reduced loosely adsorbed silane species, decreased particle agglomeration, and increased zeta potential magnitude, resulting in a more uniform hydrodynamic size distribution compared to the dried group (Z-average ≈ 814 nm, PDI ≈ 0.44). These findings suggest that post-silanization centrifugation acts as an interfacial selection mechanism that distinguishes covalently grafted silane from weakly adsorbed species. Within the limitations of this in vitro study, further investigations under varied conditions are required to confirm broader applicability. Full article

A comparative investigation of the corrosion behavior evolution of 15%SiCp/Al-Cu-Mg aluminum matrix composites (AMC) subjected to different heat treatments in a salt spray environment containing 5wt% NaCl was performed. Metallographic microscopy was used to observe the surface morphology of the corroded materials. Field-emission transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used for microstructural evaluation and elemental analysis of the samples. Polarization curves and electrochemical impedance spectroscopy (EIS) were also employed to investigate the corrosion performance of the particle-reinforced aluminum matrix composites under different heat treatments. The test results indicate that, in addition to the influence of various grain boundary precipitates and electrochemical inhomogeneities between the precipitate-free zone (PFZ) and the aluminum matrix, differences in electrochemical properties between the SiC reinforcement particles and the aluminum alloy matrix are also a primary factor contributing to the corrosion of the aluminum-based composites in a 5wt% NaCl salt spray environment. Microstructural observations and electrochemical testing of AMC specimens at different corrosion stages indicate that under-aged samples exhibit relatively higher intergranular corrosion susceptibility. Under prolonged exposure to a salt spray environment, the over-aged specimen exhibited more pronounced galvanic corrosion phenomena, specifically, a significant decrease in Charge transfer resistance (R_ct) values and an increase in CPE values. R_ct results indicate that naturally aged AMC exhibits higher corrosion resistance than artificially aged AMC. With increased salt spray corrosion time, varying degrees of crevice corrosion occurred at the Al–SiC interface in all heat-treated samples. Full article

In this study, an electrochemical sensor based on magnesium zirconate (MgZrO₃) synthesized using a deep eutectic solvent (DES)-assisted approach was developed for the detection of dopamine. The structural and morphological properties of MgZrO₃ were characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, energy-dispersive spectroscopy, and elemental mapping. The electrochemical performance of the MgZrO₃-modified glassy carbon electrode (GCE) was evaluated using cyclic voltammetry and differential pulse voltammetry. The MgZrO₃/GCE exhibited an enhanced redox response and a reduced oxidation potential for dopamine in phosphate-buffered solution (PBS, pH 7.0), indicating improved electrocatalytic activity compared to the bare electrode. This improvement is attributed to the material’s increased active surface area and facilitated charge transfer kinetics. Under optimized conditions, the sensor showed a linear response over a concentration range of 0.3–80 µM, with a detection limit of 127 nM and quantification limit of 423 nM. The MgZrO₃/GCE also demonstrated good selectivity in the presence of common interfering species and was successfully applied for dopamine detection in biological samples, with satisfactory recovery results. The findings presented here contribute to the growing body of knowledge in the field and open up new possibilities for the development of advanced electrochemical sensors for neurotransmitter detection in clinical and research settings related to Breast Cancer Treatment. Full article

Microplastics (MPs), particularly low-density polyethylene (LDPE), are widespread pollutants in aquatic environments and may affect cyanobacterial physiology. This study investigated the concentration-dependent effects of LDPE-MPs on the physiology and transcriptomic responses of Arthrospira platensis. Cultures were exposed to 10–5000 mg/L LDPE-MPs (nominal size ≤ 500 µm) for 16 days. Low to moderate concentrations (10–1000 mg/L) produced minimal effects on growth, biomass accumulation, or pigment contents. In contrast, higher concentrations (3000–5000 mg/L) were associated with reduced growth and biomass, accompanied by declines in chlorophyll a (Chl a) and phycobiliproteins over time. By day 16 at 5000 mg/L, biomass and Chl a decreased to 1.47 ± 0.03 g/L and 8.39 ± 0.24 µg/mL, respectively, compared with 1.64 ± 0.04 g/L and 10.81 ± 0.52 µg/mL in the control (p < 0.05). Accordingly, Chl a yield decreased by 13%. Field-emission scanning electron microscopy revealed adhesion of LDPE particles to filament surfaces and the formation of extracellular polymeric substance (EPS)-rich aggregates, which may influence light availability and nutrient exchange. Transcriptomic analysis indicated changes in several metabolic pathways, including nitrogen assimilation, photosynthetic electron transport, carbon metabolism, and metal homeostasis, together with differential expression of genes related to stress responses and EPS biosynthesis. Overall, these findings suggest that relatively high concentrations of LDPE microplastics may influence physiological and metabolic processes in A. platensis. Full article

In this study, composite silica-containing nanostructures were biosynthesized from residual rice husk through a fermentative process using Aspergillus niger at room temperature without calcination. The obtained nanostructures were initially characterized by UV–Vis spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), and field-emission scanning electron microscopy (FE-SEM) to determine their optical and structural properties compared with chemically synthesized silica. The results demonstrated the successful formation of composite silica-containing amorphous nanostructures under ambient conditions without the use of calcination or mineral acids. UV–Vis analysis revealed intense absorption in the deep ultraviolet region, attributed to electronic transitions associated with Si–O–Si bonds within the amorphous silica network. FTIR analysis enabled the identification of functional groups present on the material surface, providing direct evidence of the nanostructures’ chemical composition. Additionally, FE-SEM micrographs showed that the rice husk surface after biosynthesis exhibited a rough and porous texture with a morphology consistent with the formation of composite silica-containing amorphous nanostructures, in agreement with the characteristic Si–O–Si vibrational bands observed in the FTIR spectra and the strong ultraviolet absorption detected by UV–Vis analysis. Full article

Environmental concerns associated with the construction industry have drawn increasing attention worldwide. This study addresses the dual challenges of carbon emissions from cement production and construction waste disposal by developing and characterizing a fiber-modified geopolymer recycled aggregate porous concrete (GRAPC). An orthogonal experiment first optimized the GRAPC mix proportion (slag content = 40%, alkali modulus = 1.4, alkali content = 8%). Subsequently, the effects of coir, basalt, and steel fibers (0.25% and 0.5%) on its properties were investigated through laboratory experiments combined with scanning electron microscopy (SEM) analysis. The results show that steel fibers at 0.25% dosage enhanced compressive strength by approximately 25% due to their effective stress-bearing capacity. In contrast, 0.5% coir and basalt fibers reduced compressive strength by approximately 20.5% and 22.2%, respectively, due to low intrinsic strength and agglomeration. In addition, 0.25% coir and steel fibers increased effective porosity by 18.4% and 17.4%, respectively, owing to their uniform dispersion. All fibers promoted a more ductile-like failure mode, with coir fibers providing the best toughness improvement. This study elucidates how fiber type and dosage regulate the macro-properties and micro-mechanisms of GRAPC, providing a basis for designing sustainable eco-friendly concrete with great potential for non-primary load-bearing engineering fields. Full article

The recycling of technical textile waste represents a major challenge due to the complex and multilayered structure of these materials. Firefighter protective clothing, mainly composed of high-performance aramid fibers combined with polymeric membranes and auxiliary textile components, is commonly landfilled or incinerated at the end of its service life, resulting in a significant environmental impact. This work utilized recycled aramid-rich textile waste obtained from end-of-life firefighter protective clothing as reinforcement for polyamide 6 to develop high-performance thermoplastic composites within a circular economy framework. Composites containing 15, 30, 45, and 60 wt.% of recycled textile waste were manufactured by melt compounding followed by injection molding. In addition, a selected formulation containing 30 wt.% reinforcement was compatibilized using an amino-functional silane to improve interfacial adhesion. The materials were systematically characterized in terms of tensile properties, thermal behavior, thermomechanical performance, water uptake, flammability, colorimetric properties, and fracture morphology by field emission scanning electron microscopy. The results revealed a pronounced increase in stiffness and thermomechanical stability, with tensile strength increasing from approximately 65 MPa for neat PA6 up to 78 MPa at 30 wt.% reinforcement, and elastic modulus exceeding 5000 MPa at high reinforcement contents. An optimal balance between mechanical performance and ductility was achieved at 30 wt.% reinforcement, while higher contents enabled a substantial extension of the service temperature range, with HDT values increasing from 55 °C for neat PA6 up to 173 °C for highly reinforced systems. FESEM analysis confirmed improved interfacial adhesion in silane-compatibilized systems, explaining the enhanced mechanical and thermomechanical behavior. Furthermore, the incorporation of recycled aramid-rich textile waste led to a significant improvement in flame retardancy, enabling UL-94 V-0 classification at 30 wt.% reinforcement and above, without the use of additional flame-retardant additives, enabling UL-94 V-0 classification without additional flame-retardant additives. Overall, this study demonstrates the technical feasibility and high added-value potential of valorizing firefighter protective clothing waste into advanced PA6-based composites with enhanced mechanical, thermal, and fire-resistant properties, providing a sustainable route for the valorization of high-performance textile waste. Full article

The increasing incidence of multidrug-resistant bacteria has generated an urgent need for innovative antimicrobial materials that inhibit microbial growth through physical and chemical surface interactions, as opposed to traditional biochemical methods. In this work, we synthesized a composite of graphene oxide (GO), single-layer graphene (SLG), and delaminated MXene (d-MXene) by an ultrasonication-assisted technique. The synthesized materials were characterized using powder X-ray diffraction (PXRD), Field-Emission Scanning Electron Microscopy (FE-SEM), and Energy-Dispersive Spectroscopy (EDS) with elemental mapping to examine the structure and morphology of the GO/SLG/d-MXene composite. Antimicrobial activity was evaluated against E. coli using the optical density method. The GO/SLG/d-MXene composite exhibited superior antibacterial activity compared to GO, SLG, and d-MXene. These results indicate that the GO/SLG/d-MXene composite may serve as a promising antibacterial material. These nanomaterials may be further explored for surface-related antimicrobial applications in healthcare, sanitation, and environmental settings such as coatings for medical devices, disinfectant surfaces in hospitals, and treatment of contaminated water sources. Full article

The rational design of electrode materials with tailored composition and architecture is crucial for advancing high-capability electrochemical energy storage systems. This study reports that gadolinium-modified NiFe₂O₄ nanosheet electrodes were effectively synthesized on nickel foam via a hydrothermal approach followed by thermal treatment. A series of compositions (NiFe, NiFe–Gd1, NiFe–Gd2, and NiFe–Gd3) were prepared to systematically examine the effect of Gd incorporation on structural features and electrochemical properties. X-ray diffraction (XRD) analysis confirmed the formation of the cubic spinel NiFe₂O₄ phase without detectable secondary phases, indicating that the crystal structure remains intact after Gd introduction. X-ray photoelectron spectroscopy (XPS) further verified the presence of Ni²⁺, Fe³⁺, and Gd³⁺ species within the lattice environment. Morphological analysis using field-emission scanning electron microscopy (FESEM) revealed a nanosheet-based architecture, where the optimized NiFe–Gd2 electrode exhibited a porous and interconnected nanosheet framework with abundant exposed edges. This structural configuration improves electrolyte penetration and facilitates efficient ion transport during charge storage processes. Electrochemical measurements demonstrated that the NiFe–Gd2 electrode delivers an areal capacitance of 5235 mF cm⁻² at 10 mA cm⁻², along with improved reaction kinetics and low internal resistance. An asymmetric supercapacitor assembled using NiFe–Gd2 as the positive electrode and activated carbon as the negative electrode operated stably within a 0–1.5 V potential window, achieving an energy density of 0.136 mWh cm⁻² and a power density of 3.14 mW cm⁻², while retaining 86.55% of its initial capacitance after 7000 cycles. These results highlight the potential of rare-earth engineering as a viable strategy for designing advanced spinel ferrite electrodes and pave the way for the development of high-performance, durable, and scalable supercapacitor systems for practical energy storage applications. Full article

As one of the core technologies in modern national defense and security fields, infrared stealth technology aims to realize the controllable regulation of the radiation characteristics of targets in the infrared band. This paper focuses on a novel electrochromic device with a structure of WO₃/nickel mesh/Al³⁺-Zn²⁺gel electrolyte/zinc foil. The structural composition and working mechanism are systematically analyzed, and the infrared stealth regulation performance is emphatically studied. The WO₃ thin film and device structure were characterized by scanning electron microscopy (SEM). The infrared emissivity modulation and optical response properties of the device were measured using an infrared thermal imager and a UV-Vis-NIR spectrophotometer. The prepared WO₃ film exhibits a dense spherical morphology, indicating excellent uniformity and compactness. After 1000 cycles, the areal capacitance of the device remains 83.7% of its initial value, demonstrating good cycling stability. Under the voltage regulation of −0.1 V to 1.1 V, the emissivity ε of the device at the typical mid-wave infrared wavelength of 4.0 μm decreases from 0.89 (−0.1 V) to 0.67 (1.1 V), with an absolute modulation amplitude Δε of 0.22. At the typical long-wave infrared wavelength of 8.7 μm, ε decreases from 0.96 (−0.1 V) to 0.69 (1.1 V), with an absolute modulation amplitude Δε of 0.29. The electrochromic switching times for coloring and bleaching are 10.1 s and 2.44 s, respectively. According to infrared thermal imaging tests, in the temperature range of 30–40 °C, the surface temperature difference ΔT between the colored state and bleached state increases from 4.3 °C to 4.6 °C. The maximum regulation amplitude reaches 4.6 °C at 40 °C. The device achieves efficient regulation of infrared emissivity through the electrochromic effect, providing a new device design strategy for infrared stealth technology. Full article

One of the significant causes of failure in aerospace engine components is high-temperature oxidation. Therefore, it is necessary to investigate the high-temperature oxidation behavior of newly fabricated structural materials for aerospace components. From this perspective, the isothermal oxidation behavior and kinetics of newly developed stainless steel (SS) 08X14H were investigated at 750, 950 and 1050 °C for up to 100 h in an air environment. The weight results demonstrate that oxidation in 08X14H increases with time and temperature and follows a parabolic rate law. Major spallation was observed in samples oxidized for 100 and 24 h at 950 °C and 1050 °C, respectively. Structural and morphological analysis of oxidized samples through X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) of the surface and cross section reveal the phases present and their distribution. The structural results confirm the formation of Fe₂O₃, Cr₂O₃, FeCr₂O₄ and intermediate (Cr, Fe)₂O₃ oxides in the oxidized samples. Surface morphologies reveal that the formation of a Cr₂O₃ layer effectively protects the material from further oxidation. At higher temperatures, the coarsening of Fe₂O₃ oxides takes place, which leads to the formation of loose and porous oxide scale with stress-induced cracks. The spallation of the outermost Fe₂O₃-rich oxide scale was observed, and the matrix is exposed during the extreme oxidation at 950 and 1050 °C for 100 and 50 h, respectively. The cross-sectional morphologies and elemental mapping results reveal a duplex oxide layer with an outermost Fe₂O₃ layer followed by an underlying layer of Cr₂O₃, (Cr, Fe)₂O₃ and FeCr₂O₄ spinel beneath the Fe₂O₃ layer. Full article