Search Results (145)

Utilizing deep eutectic solvents (DESs) combined with microwave-assisted extraction (MAE) provides a sustainable method for extracting bioactive compounds from the macroalgae Ascophyllum nodosum and Laminaria hyperborea. Two DES formulations, choline chloride/lactic acid (ChCl/LA) and sodium acetate/lactic acid (AcNa/LA), were evaluated under varying extraction conditions. For L. hyperborea, ChCl/LA at 150 °C for 10 min yielded a total phenolic content (TPC) of 15.34 mg GAE/g DW, with antioxidant activities measured by DPPH (34.55 mg TE/g DW) and ABTS (27.06 mg TE/g DW). Extending the extraction to 20 min at 130 °C increased the TPC to 19.12 mg GAE/g DW. A. nodosum exhibited higher bioactivity, with the TPC reaching 47.51 mg GAE/g DW under the same conditions. High-performance liquid chromatography (HPLC) identified significant phenolics such as 3,4-dihydroxybenzoic acid (678.05 µg/g DW) and vanillin (6718.5 µg/g DW). Antimicrobial assays revealed strong inhibition (zones > 20 mm) against Clostridium perfringens, moderate activity against Staphylococcus aureus, and selective activity against Escherichia coli. FT-IR confirmed the presence of phenolics, polysaccharides, and lipids. Thermal and structural characterization revealed that A. nodosum residue showed an amorphous structure, while L. hyperborea retained crystallinity with decomposition profiles indicating potential bioenergy potential. SEM images revealed significant cell wall disruption correlating with extraction efficiency. These results demonstrate DES–MAE as an effective, green strategy for producing high-value algal extracts and valorizing residual biomass for biotechnological applications. Full article

The Qinghai–Tibet Plateau features a high-altitude, cold, and arid climate, with harsh environmental conditions. It is also one of the regions in China where chloride-rich salt lakes are abundant. These circumstances pose significant challenges to the durability of concrete. This study explored the impact of recycled fine powders (RFP) on the resistance of concrete to chloride ion erosion. To evaluate this, a 3.5% sodium chloride solution and Qarhan Salt Lake brine were employed as erosion media. The depth and concentration of chloride ion penetration, the free chloride ion diffusion coefficient (D_f), and the microstructure of the concrete were measured. The results demonstrated that when the replacement rate of RFP was 20%, the concrete displayed excellent resistance to chloride ion erosion in both the sodium chloride solution and the Salt Lake brine. XRD analysis and SEM images revealed that the addition of RFP enabled the concrete to bind more Cl⁻ to form Friedel’s salt, which filled the pores of the concrete and reduced the diffusion of Cl⁻ within the concrete. Moreover, as the soaking time extended continuously, the erosion and damage effects of the Salt Lake brine solution on the concrete were more severe than those of the sodium chloride solution. Full article

In the Southeastern Ordos Basin, the Chang 2 low-permeability sandstone reservoir of the Triassic Yanchang Formation is a typical heterogeneous reservoir. Quantitatively characterizing and analyzing its complex pore throat structure has become crucial for enhancing storage and production in the study area. The pore throat structure is a key factor influencing reservoir properties. To achieve this, a comprehensive suite of analytical techniques was employed, including cast thin section (CTS), scanning electron microscopy (SEM), cathodoluminescence (CL), X-ray diffraction (XRD), and mercury intrusion capillary pressure (MICP). This study quantitatively characterizes the pore size distribution of reservoirs in the Southeast Ordos Basin. Based on fractal theory, it clarifies the complexity of the pore throat structure and the degree of microscopic heterogeneity at different scales. Finally, this study reveals the correlation between fractal dimensions and storage and permeability capacities and analyzes the controlling factors. The findings indicate that the predominant lithotype in the study area is fine-grained feldspar sandstone, which develops pore types such as intergranular pores, dissolution pores, and microfractures. Based on the shapes of mercury injection curves and pore throat structural parameters, and in conjunction with SEM images, the samples are categorized into three types. Type I samples exhibit good pore throat connectivity and are characterized by a lattice model. Type II samples are characterized by a tubular pore throat model. Type III samples have poor pore throat connectivity and are characterized by an isolated model. The pore throat network of low-permeability sandstone is primarily composed of micropores (pore throat radius r < 0.1 μm), mesopores (0.1 < r < 1.0 μm), and macropores (r > 1.0 μm). The complexity of the reservoir pore throat structure was quantitatively characterized by fractal theory. The total fractal dimension (D) of all the samples is between 2 and 3, which indicates that the reservoir has capillary fractal characteristics. The average fractal dimension of micropores (D1) is 2.57, while that for mesopores (D2) and macropores (D3) is slightly higher, at an average of 2.68. This suggests that micropores have higher self-similarity and homogeneity. The fractal dimensions D1, D2, and D3 of the three types of reservoirs all exhibit a negative correlation with porosity and permeability. This shows that the more complex the pore throat structure is, the worse the storage and seepage capacity of the reservoir. For type I samples, the correlation of D3 with pore throat structural parameters such as entry pressure, skewness, and maximum mercury saturation is better than that of D2 and D1. For type II and type III samples, D2 shows a significant correlation with pore throat structural parameters. This indicates that the heterogeneity and complexity of mesopores are key factors influencing the pore throat structure of poor-quality reservoirs. Different mineral compositions have varying effects on the fractal characteristics of pore structures. Quartz, feldspar, and clay exert both negative and positive dual impacts on reservoir quality by altering the pore throat structure and the diagenetic processes. The mineral content exhibits a complex quadratic relationship with the fractal dimension. Moreover, micropores are more significantly influenced by the mineral content. The study of the relationship between the fractal dimension and physical properties, pore throat structural parameters, and mineral composition can improve the understanding of the reservoir quality of low-permeability reservoirs. This provides a theoretical basis for exploration and improving the recovery rate in the study area. Full article

Siderite and baryte are common non-sulphide phases in sedimentary exhalative (SEDEX) deposits, but their formation remains poorly understood. Siderite is important as an exploration vector in some deposits, whereas baryte is important as a S source in some deposits. The past-producing Walton deposit (Nova Scotia, Canada) consists of two ore types: (1) a sulphide body primarily hosted by sideritised Viséan Macumber Formation limestone (0.41 Mt; head grade of 350 g/t Ag, 4.28% Pb, 1.29% Zn, and 0.52% Cu), and (2) an overlying massive baryte body of predominantly microcrystalline baryte (4.5 Mt of >90% baryte). This study used optical microscopy, SEM-EDS, cathodoluminescence (CL), LA-ICP-MS, and SIMS sulphur isotope analysis of siderite and baryte to elucidate their origin and role in deposit formation. Siderite replaces limestone and contains ≤9 wt. % Mn, is LREE-depleted (PAAS-normalised REEY diagrams), and has low (<20) Y/Ho ratios. Sideritisation occurred due to dissimilatory iron reduction (DIR) that led to the breakdown of Fe-Mn-oxyhydroxides and organic matter, as indicated by light δ¹³C_VPBD values and negative Y anomalies. The baryte body is dominated by a microcrystalline variety that locally develops a radial texture and coarsens to a tabular variety; it also occurs intergrown with, and as veins in, massive sulphides. Based on fluid inclusion data from previous studies, the coarser baryte types grew from a hot (>200 °C) saline (25 wt. % NaCl) fluid containing CO₂-CH₄ and liquid petroleum. Marine sulphate δ³⁴S_VCDT values typical of the Viséan (~15‰) characterise the baryte body and some tabular baryte types, whereas heavier (~20‰) and lighter (~10‰) values typify the remaining tabular types. The variations in tabular baryte relate to distinct zones identified by CL imaging and are attributed to the sulphate-driven anaerobic oxidation of methane (SDAOM) and oxidation of excess H₂S after sulphide precipitation. These results highlight the importance of hydrocarbons (methane and organic matter) in the formation of both the siderite and the baryte at Walton and that DIR and the SDAOM can be important contributing processes in the formation of SEDEX deposits. Full article

Recent advancements in smart textiles have facilitated their extensive application in wearable health monitoring, particularly in brain activity measurement. This study introduces a flexible and washable fabric dry electroencephalography (EEG) electrode designed for brain activity measurement. The fabric dry electrode is constructed from electrically conductive polyester fabric with a resistivity of 0.09 Ω·cm, achieved by applying a PEDOT: PSS/PVA conductive paste coating on the textile substrate. A comparative analysis of the tensile properties between the conductive and untreated polyester fabric was conducted. The SEM images demonstrated that the PEDOT: PSS/PVA conductive polymer composite resulted in a uniform coating on the fabric surface. When enveloped in elastic foam, the fabric dry electrode maintained a low and stable electrode–skin contact impedance during prolonged EEG monitoring. Additionally, the short circuit noise level of the fabric dry electrode exhibited superior performance compared to both Ag/AgCl wet and finger dry electrode. The EEG signals acquired from the fabric dry electrode were comparable to those recorded by the Ag/AgCl wet electrode. Moreover, the fabric electrode effectively captured clear and reliable EEG signals, even after undergoing 10 washing cycles. The fabric dry electrode indicates good sweat resistance and biocompatibility during prolonged monitoring. Full article

Cellulose is a versatile biopolymer increasingly applied in medicine and industry due to its biodegradability and biocompatibility, along with the renewability and large availability of source materials. However, finding simple, eco-friendly, and effective methods to modify cellulose to provide it with new functionalities remains a challenge. This work presents a new, inexpensive, and eco-friendly method to chemically modify microcrystalline cellulose (MCC) by the submerged cold plasma treatment of an aqueous suspension of MCC containing different oxidizing agents, such as hydrogen peroxide (H₂O₂), sodium hypochlorite (NaClO), or sodium periodate (NaIO₄). Fourier-transform Infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) showed that plasma treatment intensified the oxidizing effect of H₂O₂, NaClO, and NaIO₄, with plasma-assisted NaClO treatment yielding the highest MCC oxidation level. XPS indicated that the plasma-assisted oxidations also resulted in different degrees of chemical degradation of MCC, a finding further supported by the thermogravimetric analysis (TGA) results. X-ray diffraction (XRD) data revealed a different effect of the oxidizing agents on the crystalline and amorphous regions in MCC. Scanning electron microscopy (SEM) images showed that the combined treatment with plasma and chemical oxidizing agents led to MCC fragmentation and varying degrees of defibrillation into nanofibers. Full article

Four kinds of silicone hydrogel transparent contact lenses (CLs) with different formulations were prepared by the free radical photocuring polymerization. By mixing polyethylene glycol diacrylate (PEGDA) of 1000 Da with ethylene glycol dimethacrylate (EGDMA) and adding other silicone monomers and hydrophilic monomers, the transparency and flexibility of the material were successfully achieved. By optimizing the weight percentage of each component, the best balance of optical performance can be achieved. The photocuring properties of the materials were characterized by electronic universal test, double-beam UV-visible spectrophotometer, Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The results showed that the addition of higher PEGDA content reduces the elastic modulus, improves curing efficiency, improves equilibrium water content (EWC), and enhances light transmission. Hydrogels containing only high PEGDA but no EGDMA showed similar curing rates, water content, and elastic modulus, but had the worst optical transparency, far inferior to the materials mixed with PEGDA and EGDMA. Additionally, imaging performance of the CLs was further evaluated through simulation analysis using Ansys Zemax OpticStudio2024 software. This research provides a new choice of material consideration to improve the performance and wearing comfort of CLs. Full article

Submicron-sized TiB₂ powders (300 nm–1 μm) were prepared by the reaction of TiC, B₄C, and Ca assisted by molten CaCl₂. The optimal reaction procedure (1200 °C and 25 wt.% CaCl₂ + 25 wt.% Ca) was obtained by exploring the effects of the boronization reaction temperature and the addition of an amount of CaCl₂. It was found that the introduction of CaCl₂ not only promoted the reaction but also effectively inhibited the volatilization of excess Ca. Furthermore, SEM images of the products showed that the morphology and particle size of TiB₂ were inherited from the carbothermal reduction product TiC, which was dominated by the “template/growth” mechanism. The process of the boronization reaction was that B atoms migrated from B₄C and replaced the C atoms in the lattice of TiC. Full article

In this study, the behavior of sodium silicate (Na₂SiO₃), manganese sulfate monohydrate (MnSO₄·H₂O), and ammonium metavanadate (NH₄VO₃) as corrosion inhibitors for AA6061 aluminum alloy (Al) was investigated. The polarization resistance (R_p) of the Al substrate immersed in 0.1 M NaCl solution was found to be 13 kΩ·cm². In comparison, the R_p of the Al substrate immersed in 0.1 M NaCl in the presence of Na₂SiO₃, Na₂SiO₃/MnSO₄·H₂O, and Na₂SiO₃/NH₄VO₃ inhibitors was found to be 100, 133, and 679 kΩ·cm², respectively. The best inhibition result was obtained when the mixture of the inhibitors was used with R_p of 722 kΩ·cm². The maximum percentage of the corroded area calculated from the scanning electron microscopy (SEM) images was found to be 5.7% for Al substrate immersed in 0.1 M NaCl, which decreased to 0.06% when the mixture of the inhibitors was used. The synergetic effects between the three inhibitors were studied, and the results illustrated that the combination of Na₂SiO₃, MnSO₄·H₂O, and NH₄VO₃ provided the best corrosion inhibition properties for Al in aqueous NaCl environments. Full article

Modern research technology’s goal is to produce multifunctional materials that require low energy. In this work, we have applied polypyrrole (PPy) doped with dodecyl benzenesulfonate (DBS-) with the addition of polyoxometalates (POM) such as phosphotungstic acid (PTA) forming PPyDBS-PT composites. Two different PTA concentrations (4 mM and 8 mM) were used to form PPyDBS-PT4 and PPyDBS-PT8. The higher concentration of PTA created a highly dense and compact film which can be observed from scanning electron microscopy (SEM cross-section image), and also contains fewer phosphotungstate anions (PT³⁻) inclusion (via energy-dispersive X-ray spectroscopy, EDX). Three different aqueous electrolytes, LiCl (lithium chloride), NaCl (sodium chloride), and KCl (potassium chloride), were applied to investigate how those alkali metal ions perform as typical cation-driven actuators. Cyclic voltammetry with linear actuation revealed the tendency LiCl > NaCl > KCl in view of better strain, charge density, electronic conductivity, and Young’s modulus of PPyDBS-PT4 outperformed PPyDBS-PT8. Chronopotentiometric measurements showed high specific capacitance for PPyDBS-PT4 at 260.6 ± 21 F g⁻¹ with capacity retention after 5000 cycles of 88.5%. The sensor calibration of PPyDBS-PT4 revealed that the alkali cations (Li⁺, Na⁺, and K⁺) can be differentiated from each other. The PPyDBS-PT4 has multifunctional applications such as actuators, sensors, and energy storage. Full article

Sodium tungstate (Na₂WO₄) was filled into the micropores and onto the surface of a magnesium alloy microarc oxidation (MAO) coating by means of vacuum impregnation. Subsequently, the coating was sealed through silane treatment to synergistically boost its corrosion resistance. The phase composition of the coating was inspected using XRD. FTIR was utilized to analyze the functional groups in the coating. XPS was employed to study the chemical composition and valence state of the coating. The surface and cross-sectional morphology of the coating, along with its elemental composition and distribution, were investigated by SEM and EDS. Meanwhile, the thickness of the coating was analyzed using Image J software. Electrochemical impedance spectroscopy (EIS) was employed to determine the corrosion resistance of the coating. The results show that compared with an MAO coating, M-0.125W composite coating (only filled with sodium tungstate on the surface of the MAO coating), and M-SG composite coating (only receiving silanization treatment applied to the surface of the MAO coating), the corrosion resistance of the M-nW-SG composite coating (loaded with sodium tungstate on the surface of the MAO coating and then treated with silane) is significantly improved. This is mainly attributed to the fact that sodium tungstate can be combined with Mg²⁺ to form insoluble magnesium tungstate protective film, which blocks corrosion media. At the same time, silanization treatment further seals the MAO coating and increases the compactness of the coating. In addition, with the increase in the impregnation concentration of sodium tungstate, the content of sodium tungstate in the M-nW-SG composite coating improves, and the sealing effect of silanization treatment is better. When the impregnation concentration of sodium tungstate is 0.1 mol/L or above, the MAO coating with sodium tungstate can be completely sealed. When the impregnation concentration of sodium tungstate is 0.125 mol/L, M-0.125W-SG composite coating has the best corrosion resistance, and its impedance modulus value can be maintained at 8.06 × 10⁶ Ω·cm² after soaking in 3.5 wt.% NaCl solution for 144 h, which is about three orders of magnitude higher than those of MAO coating and M-0.125W and M-SG composite coatings. Full article

In this study, an electrochemical approach was utilized to degrade the anionic Chlorazol Yellow (CY) dye in an aqueous solution using a lead oxide-modified stainless steel electrode (denoted as PbO₂-SS). The fabrication of this electrode involved scanning a clean stainless steel (denoted as SS) plate within a range of −1.0 V to +1.0 V against Ag/AgCl (saturated KCl) for three cycles at a scan rate of 0.1 V s⁻¹ in a 0.1 M Pb(NO₃)₂ solution. Analysis via X-ray photoelectron spectroscopy (XPS) confirmed successful fabrication, with Pb⁴⁺ being the predominant species observed in the XPS spectra. Additionally, scanning electron microscopy (SEM) imaging of the fabricated electrode revealed the deposition of PbO₂ in a flower-like, nanostructured form on the SS surface. To provide a cost-effective method for dye treatment, the PbO₂-SS anode was utilized to oxidize chloride ions (Cl⁻) into hypochlorite ions (ClO⁻), which subsequently oxidized CY molecules. Optimization of parameters such as the voltage, supporting electrolytes, and solution pH was conducted to determine the most effective degradation conditions. The method achieved a degradation efficiency of approximately 97% over a wide pH range within 20 min, indicating its applicability across various pH conditions. Consequently, this technique presents a promising approach for the treatment of industrial wastewater. Full article

To address the issue of uneven shear strength distribution in dredged sediment during electroosmosis treatment, a grouting system was employed to inject CaCl₂ into the anode region and Na₂SiO₃ solution into the central region. An experimental study was conducted to examine the effect of injection timing on the electrochemical treatment of dredged sediment. Five experimental groups, each with different Na₂SiO₃ injection timings, were established. The impact of injection timing on the macroscopic electrochemical reinforcement was assessed based on current, drainage volume, settlement, moisture content, and shear strength. Additionally, the ion concentration of effluent from the cathode was measured, and scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) were employed to analyze ion migration and pore characteristics. The results indicated that when CaCl₂ was injected into the anode at the start of the experiment and Na₂SiO₃ was injected into the central region after the current had decayed by 70% from its peak, the drainage volume reached its maximum. Under these conditions, the average shear strength increased from nearly 0 kPa to 48.2 kPa, yielding the optimal reinforcement effect. The strength in both the central and cathode regions also improved, and the strength distribution between the anode and cathode became more uniform, with the strength ratio decreasing from 1.91 to 1.65, thereby enhancing the overall soil strength distribution. The Na⁺ concentration in the cathode effluent was highest, suggesting that Na⁺ migration played a predominant role in electroosmotic drainage. Furthermore, the electrochemical reactions generated cementitious materials that effectively filled the soil pores. SEM imaging and MIP pore size analysis revealed a reduction in porosity and an increase in soil compaction. Full article

Due to their excellent mechanical properties and corrosion resistance, high-entropy alloys (HEAs) have the potential to be used as new engineering structures and functional materials. In this study, an FeCo_1.5CrNi_1.5Ti_0.5HEA coating was prepared on the surface of a 1Cr18Ni9Ti alloy by laser cladding technology. Phase structure and microstructure were characterized by XRD and using an SEM. The corrosion resistance was evaluated by an electrochemical workstation, and the polarization curves were obtained in simulated seawater and 3.5 wt.% NaCl and 5% HCl solutions. The corrosion morphology of the Fe-based HEA coating was further characterized using the SEM, super depth of field observation, and 3D topological images. The results showed that the Fe-based HEA coating had a single-phase FCC structure with a grain size of about 10.7 ± 0.25 μM. Electrochemical analysis results showed that the corrosion resistance of the current Fe-based HEA coating was poor in HCl solutions. However, it exhibited good corrosion properties in simulated seawater and 3.5 wt.% NaCl solutions. Further analysis of the corrosion morphology revealed that in simulated seawater and the 3.5 wt.% NaCl solution, the surface of the current Fe-based HEA coating exhibited a preferential corrosion tendency between dendrites, while in the 5% HCl solution, it exhibited more obvious pitting characteristics. The results indicate that the current Fe-based HEA coating exhibits good comprehensive performance, especially in an acidic Cl⁻ corrosion environment. These findings provide a reference for the application of laser cladding prepared Fe HEA coatings. Full article

Micro- and nano-structures of ZnO were synthesized by the vapor–solid method at 600, 700, and 800 °C in atmospheres of Ar and air, at atmospheric pressure. The structural characterization XRD shows that the nano-structures synthesized in air atmosphere at 600 °C, while diffraction peaks were found due to Zn because the presence of metallic Zn remains on the surface of the pellet. SEM images show that the morphologies range from nano-wires to micro-tubes. When cathodoluminescence is measured in micro-tubes, there is a shift of the near-band edge of the ZnO toward red; this is due to structural defects in the ZnO network. This result is corroborated with panchromatic CL measurements, which exhibit a difference in brightness between the micro-tubes. Furthermore, EDS measurements show an atomic quantity ratio of Zn:O that differs from the stoichiometric composition in the micro-tubes. The photocatalytic activity of three types of structures—nano-wires, micro-tubes, and micro-rods under UV irradiation using methylene blue as a model pollutant—were evaluated. The best response was obtained for nanowires, not only because they have a larger surface area but also because of the present defects. Full article