Search Results (12,305)

As a potential strategic resource of critical metals, deep-sea cobalt-rich crusts represent one of the most promising metal reservoirs within oceanic seamount systems, and their metallogenic mechanism constitutes a frontier topic in deep-sea geoscience research. This review focuses on the cobalt-rich crusts from the Magellan Seamount region in the northwestern Pacific and synthesizes existing geological, mineralogical, and geochemical studies to systematically elucidate their mineralization processes and metal enrichment mechanisms from a microstructural perspective, with particular emphasis on cobalt enrichment and its controlling factors. Based on published observations and experimental evidence, the formation of cobalt-rich crusts is divided into three stages: (1) Mn/Fe colloid formation—At the chemical interface between oxygen-rich bottom water and the oxygen minimum zone (OMZ), Mn²⁺ and Fe²⁺ are oxidized to form hydrated oxide colloids such as δ-MnO₂ and Fe(OH)₃. (2) Key metal adsorption—Colloidal particles adsorb metal ions such as Co²⁺, Ni²⁺, and Cu²⁺ through surface complexation and oxidation–substitution reactions, among which Co²⁺ is further oxidized to Co³⁺ and stably incorporated into MnO₆ octahedral vacancies. (3) Colloid deposition and mineralization—Mn–Fe colloids aggregate, dehydrate, and cement on the exposed seamount bedrock surface to form layered cobalt-rich crusts. This process is dominated by the Fe/Mn redox cycle, representing a continuous evolution from colloidal reactions to solid-phase mineral formation. Biological processes play a crucial catalytic role in the microstructural evolution of the crusts. Mn-oxidizing bacteria and extracellular polymeric substances (EPS) accelerate Mn oxidation, regulate mineral-oriented growth, and enhance particle cementation, thereby significantly improving the oxidation and adsorption efficiency of metal ions. Tectonic and paleoceanographic evolution, seamount topography, and the circulation of Antarctic Bottom Water jointly control the metallogenic environment and metal sources, while crystal defects, redox gradients, and biological activity collectively drive metal enrichment. This review establishes a conceptual framework of a multi-level metallogenic model linking macroscopic oceanic circulation and geological evolution with microscopic chemical and biological processes, providing a theoretical basis for the exploration, prediction, and sustainable development of potential cobalt-rich crust deposits. Full article

Thrips are cosmopolitan agricultural pests and important vectors of plant viruses, and the increasing coexistence of multiple morphologically similar species has intensified the demand for species-specific molecular identification. However, traditional morphological identification and PCR assays using universal primers are often inadequate for mixed-species samples and field-adaptable application. In this study, we developed a species-specific molecular identification framework targeting a polymorphism-rich region of the mitochondrial cytochrome c oxidase subunit I (COI) gene, which is more time-efficient than sequencing-based COI DNA barcoding, for four economically important thrips species in southern China, including the globally invasive Frankliniella occidentalis. By aligning COI sequences, polymorphism-rich regions were identified and used to design four species-specific primer pairs, each containing a diagnostic 3′-terminal nucleotide. These primers were combined with a PBS-based DNA extraction workflow optimized for single-insect samples that minimizes dependence on column-based purification. The assay achieved a practical detection limit of 1 ng per reaction, demonstrated species-specific amplification, and maintained reproducible amplification at DNA inputs of ≥1 ng per reaction. Notably, PCR inhibition caused by crude extracts was effectively alleviated by fivefold dilution. Although the chemical identities of the inhibitors remain unknown, interspecific variation in inhibition strength was observed, with T. hawaiiensis exhibiting the strongest suppression, possibly due to differences in lysate composition. This integrated framework balances target specificity, operational simplicity, and dilution-mitigated inhibition, providing a field-adaptable tool for thrips species identification and invasive species monitoring. Moreover, it provides a species-specific molecular foundation for downstream integration with visual nucleic acid detection platforms, such as the CRISPR/Cas12a system, thereby facilitating the future development of portable molecular identification workflows for small agricultural pests. Full article

Tungsten is one of the critical materials with important applications in many areas. Electrolysis of Na₂WO₄-based salt is a short and green process for the production of tungsten metal and alloys. The conventional process for producing Na₂WO₄ is expensive and time-consuming. Scheelite (CaWO₄) is becoming the most important resource for the extraction of tungsten. Based on thermodynamic calculations and phase equilibrium studies, a novel process is proposed to prepare Na₂WO₄-based salt directly from scheelite through a high-temperature process. By reacting with silica and sodium oxide, immiscible layers of liquid salt and slag are formed from scheelite between 1200 and 1300 °C. High-density salt containing Na₂WO₄ is separated from the silicate slag, which is composed of impurities and fluxes. The effects of fluxing agents, smelting temperature, and reaction time on the direct yield of WO₃ and purity of sodium tungsten are investigated in combination with thermodynamic calculations and high-temperature experiments. The salt containing up to 99% Na₂WO₄ is obtained directly in a single process, which can be used for the production of other tungsten chemicals. This study provides a novel research method and detailed information to produce low-cost sodium tungstate directly from scheelite. Full article

To meet stringent efficiency and environmental targets, future gas turbines require increased turbine inlet temperatures while maintaining low NO${}_x$ emissions and accommodating hydrogen-blended fuels. Axially staged combustion has emerged as a key technology to address these challenges. This paper presents a mathematical model for the rapid prediction of NO emissions in axially staged combustors fueled with hydrogen-blended methane. The model integrates a simplified thermal NO mechanism with a set of dimensionless staging variables, providing a unified description of flow, mixing, and reaction processes. Its accuracy was validated against a detailed chemical reaction network (CRN). The model was applied to identify feasible low-emission staging windows across different hydrogen-blending ratios and to systematically analyze the effects of secondary-stage mixing quality, operating parameters, and fuel composition on optimal staging and emissions. Results demonstrate that coordinating the combustion strategies of the primary and secondary stages enables effective NO control across a wide fuel range. This work provides a theoretical foundation for the design of low-emission, fuel-flexible axially staged combustors. Full article

Melamine, a nitrogen-rich industrial chemical, has raised increasing concern as an emerging environmental contaminant with potential reproductive toxicity. While its nephrotoxic effects are well established, the direct impact of melamine on human sperm remains poorly defined. In this study, we investigated the in vitro effects of melamine on human sperm, under both capacitating and non-capacitating conditions. Functional analyses revealed that the exposure to 0.8 mM melamine, the highest non-cytotoxic concentration in vitro, significantly compromised sperm motility and disrupted key capacitation processes, including tyrosine phosphorylation patterns, cholesterol efflux, and the acrosome reaction. Molecular assessments demonstrated melamine-induced mitochondrial dysfunction, characterized by COX4I1 downregulation, reduced mitochondrial membrane potential, and altered reactive oxygen species production. In parallel, gene expression analyses revealed the activation of apoptotic pathways, with the upregulation of BAX and downregulation of BCL2, changes that were more pronounced during capacitation. Furthermore, melamine exposure significantly increased sperm DNA fragmentation and denaturation, indicating genotoxic stress. Collectively, these findings demonstrate that even low, non-cytotoxic concentrations of melamine compromise sperm function by disrupting capacitation, mitochondrial activity, and genomic integrity. This study identifies capacitation as a critical window of vulnerability and underscores the need to consider melamine as a potential environmental risk factor for male reproductive health. Full article

Polyurethanes (PUs) are indispensable polymeric materials widely employed across diverse industrial sectors due to their excellent thermal stability, chemical resistance, adhesion, and mechanical durability. However, the intrinsic three-dimensional crosslinked network that underpins their performance also presents a fundamental barrier to reprocessing and recycling. Consequently, most end-of-life PU waste is currently managed through landfilling or incineration, resulting in significant resource loss and environmental impact. To address these challenges, this review presents an integrated perspective on sustainable PU systems by unifying green synthesis strategies with closed-loop recovery approaches. First, recent advances in bio-based polyols and phosgene-free isocyanate synthesis derived from renewable resources—such as plant oils, carbohydrates, and lignin—are discussed as viable means to reduce dependence on petrochemical feedstocks and mitigate toxicity concerns. Next, emerging chemical recycling methodologies, including acidolysis and aminolysis, are reviewed with a focus on the selective recovery of high-purity monomers. Finally, PU vitrimers and dynamic covalent polymer networks (DCPNs) based on urethane bond exchange reactions are examined as reprocessable architectures that combine thermoplastic-like processability with the mechanical robustness of thermosets. By integrating synthesis, recovery, and reuse within a unified framework, this review aims to outline a coherent pathway toward establishing a sustainable circular economy for PU materials. Full article

In this study, a laboratory-scale slag–steel reaction experiment was conducted to systematically evaluate the influence of the initial MgO content (3–7 wt.%) in LF refining slag on the cleanliness of GCr15 bearing steel. The assessment was performed from multiple perspectives by comparing the total oxygen content (T[O]) in molten steel, the inclusion area fraction, and the inclusion number density after 30 min of slag–steel interaction. To further elucidate the thermodynamic driving forces and kinetic mechanisms governing inclusion capture by slag, a predictive slag adsorption model was developed using an in-house computational code coupled with FactSage 8.1. Under conditions of slag basicity R (CaO/SiO₂) ranging from 4.0 to 8.0, MgO content varying from 0 to 7 wt.%, and a constant Al₂O₃ content of 32 wt.%, the chemical driving force ΔC (the mass-fraction difference between slag components and inclusions), the slag viscosity η, and the combined parameter ΔC/η were calculated at 1600 °C for three representative inclusion types: Al₂O₃, MgO·Al₂O₃, and MgO. In addition, the model was employed to quantitatively characterize the adsorption capacity of slag toward Mg–Al binary inclusions under varying MgO levels. Both experimental observations and model calculations demonstrate that the slag–steel reaction markedly enhances inclusion removal, as evidenced by pronounced decreases in T[O], inclusion number density, and inclusion area fraction after reaction. With increasing MgO content in slag, T[O] and inclusion-related indices exhibit a consistent trend of first decreasing and then increasing, reaching minimum values at an MgO level of 5 wt.%. Further analysis reveals a positive correlation between the apparent inclusion-removal rate constant ko and ΔC/η corresponding to MgO·Al₂O₃ inclusions. Moreover, the slag’s adsorption capacity toward Mg–Al binary inclusions decreases overall as the MgO fraction in inclusions increases. Notably, when the MgO content in inclusions exceeds 29 wt.%, the adsorption capacity undergoes an abrupt drop, indicating a pronounced cliff-like attenuation behavior. Full article

The bonding behavior of the Ni-based superalloy CM247LC during transient liquid phase (TLP) bonding is strongly governed by filler metal chemistry, particularly boron activity. In this study, the time-dependent bonding mechanisms of CM247LC joints fabricated using a high-boron MBF-80 filler and a low-boron MBF-20 filler are systematically compared to clarifying the transition between reaction-dominated brazing and diffusion-assisted TLP bonding. Microstructural analyses reveal that MBF-80 promotes the formation of a persistent, reaction-stabilized interlayer characterized by strong boron localization and the development of boron-rich intermetallic reaction products. These features kinetically suppress diffusion-assisted homogenization and prevent isothermal solidification, resulting in pronounced chemical and mechanical discontinuities across the joint. In contrast, MBF-20 enables progressive boron depletion, suppression of stable intermetallic accumulation, and interfacial smoothing, leading to diffusion-assisted chemical redistribution and partial isothermal solidification. This evolution is accompanied by gradual convergence of hardness profiles toward that of the CM247LC base metal, indicating improved mechanical continuity. These results demonstrate that joint hardness alone is insufficient for evaluating bonding quality in CM247LC. Instead, controlled microstructural evolution governed by low-boron filler chemistry is essential for achieving chemically and mechanically compatible joints. The present work establishes a clear mechanistic link between filler metal composition and bonding behavior, providing guidance for the design of reliable TLP bonding strategies in Ni-based superalloys. Full article

Utilizing saline aquifers for carbon mineralization has proven to be a reliable approach for CO₂ storage. However, less attention has been given to CO₂ mineralization and geomechanical response at engineering durations and spatial scales. The objective of the study is to evaluate the feasibility of a potential CO₂ sequestration site in the Ordos Basin, located at a depth of approximately 1100 m, using the CMG-GEM numerical simulator. A coupled hydraulic–mechanical–chemical model was formulated, accounting for multiphase fluid flow, geochemical reactions, and geomechanical response. The simulation results indicated the following: (1) When CO₂ is injected into a saline formation, it can react with minerals. These chemical reactions may lead to the precipitation of certain minerals (e.g., calcite, kaolinite) and the dissolution of others (e.g., anorthite), potentially affecting the porosity and permeability of the storage formation; however, the study found that the effect on porosity is negligible, with only a 1.2% reduction observed. (2) The extent of ground uplift caused by CO₂ injection is strongly influenced by the injection rate. The maximum vertical ground displacements after 25 years is 6.1 cm at an injection rate of 16,000 kg/day; when the rate is increased to 24,000 kg/day, the maximum displacement rises to 9.4 cm, indicating a 54% increase. Full article

Biofuel cells (BFCs) generate electricity by converting chemical energy into electrical energy using biological systems. Saccharomyces cerevisiae (yeast) is an attractive biocatalyst for BFCs due to its robustness, low cost, and metabolic versatility; however, electron transfer from the intracellular reactions to the electrode is limited by the cell membrane. Nystatin is an antifungal antibiotic that increases the permeability of fungal membranes. We hypothesized that sub-lethal nystatin treatment could enhance mediator-assisted electron transfer without compromising cell viability. In this work, yeast was treated with nystatin during cultivation at concentrations of up to 6 µg/mL and combined with a dual-mediator system consisting of a lipophilic mediator (9,10-phenanthrenequinone, PQ) and a hydrophilic mediator (potassium ferricyanide). Scanning electrochemical microscopy revealed that the dual-mediator system increased local current responses by approximately fivefold compared to a single mediator (from ~11 pA to ~59 pA), and that nystatin-treated yeast exhibited higher local electrochemical activity than untreated yeast (maximum currents of ~0.476 nA versus ~0.303 nA). Microbial fuel cell measurements showed that nystatin treatment increased the maximum power density from approximately 0.58 mW/m² to approximately 0.62 mW/m² under identical conditions. Nystatin concentrations between 4 and 5 µg/mL maintain yeast viability at near-control levels, while higher concentrations cause a decrease in viability. These results demonstrate that controlled, sub-lethal membrane permeabilization combined with a dual-mediator strategy can enhance electron transfer in yeast-based biofuel cells. Full article

Decarbonization of compression-ignition engines requires evaluation of carbon-free and low-carbon fuel alternatives. Ammonia (${NH}_3$) offers zero direct carbon emissions but faces combustion challenges including low flame speed (7 $\mathrm{c}\mathrm{m}/\mathrm{s}$) and high auto-ignition temperature (657 °$\mathrm{C}$). Methanol provides improved reactivity and bound oxygen content that can enhance ignition characteristics. This computational study investigates diesel–ammonia–methanol ternary fuel blends using validated three-dimensional CFD simulations (ANSYS Forte 2023 R2; ANSYS, Inc., Canonsburg, PA, USA) with merged chemical kinetic mechanisms (247 species, 2431 reactions). The model was validated against experimental in-cylinder pressure data with deviations below 5% on a single-cylinder diesel engine (510 cm³, 17.5:1 compression ratio, 1500 rpm). Ammonia energy ratios were systematically varied (10–50%) with methanol substitution levels (0–90%). Fuel preheating at 530 K was employed for high-alcohol compositions exhibiting ignition failure at standard temperature. Results demonstrate that peak cylinder pressures of 130–145 bar are achievable at 10–30% ammonia with M30K–M60K configurations, comparable to baseline diesel (140 bar). Indicated thermal efficiency reaches 38–42% at 30% ammonia-representing 5–8 percentage point improvements over diesel baseline (31%)-but declines to 30–32% at 50% ammonia due to fundamental combustion limitations. ${CO}_2$ reductions scale approximately linearly with ammonia content: 35–55% at 30% ammonia and 75–78% at 50% ammonia. ${NO}_X$ emissions demonstrate 30–60% reductions at efficiency-optimal configurations. Multi-objective optimization analysis identifies the A30M60K configuration (30% ammonia, 60% methanol, 530 K preheating) as optimal, achieving 42% thermal efficiency, 58% ${CO}_2$ reduction, 51% ${NO}_X$ reduction, and 11% power enhancement versus diesel. This configuration occupies the Pareto frontier “knee point” with cross-scenario robustness. Full article

Hydrogen, as an alternative energy carrier, presents significant prospects for the transition to more environmentally friendly energy solutions. However, its efficient and safe storage remains a challenge, as materials with high adsorbent capacity and long-term storage capability are required. This study focuses on the synthesis and characterization of a composite material comprising carbon fiber and manganese dioxide (MnO₂/CFs), for the purpose of hydrogen storage. Carbon fiber was chosen as the basis for the composition of the composite material due to its large active surface area and its excellent mechanical, thermal, and electrochemical properties. The deposition of MnO₂ on the surface of carbon fibers took place through two different synthetic pathways: electrochemical deposition and chemical synthesis under different conditions. The electrochemical method enabled the production of a greater amount of oxide with optimized structural and chemical properties, whereas the chemical method was simpler but required more time to achieve comparable or lower-capacity performance. Elemental analysis of the electrochemically produced composites showcased an average of 40.5 ± 0.05 wt% Mn presence, which is an indicator of the quantity of MnO₂ on the surface responsible for hydrogen storage, while the chemically produced composites showcased an average of 7.6 ± 0.05 wt% Mn presence. Manganese oxide’s high specific capacity and reversible redox reaction participation make it suitable for hydrogen storage applications. The obtained results of the hydrogenated samples through physicochemical characterization indicated the formation of the MnOOH intermediate. Regarding these findings it may be remarked that carbon fiber/MnO₂ composites are promising candidates for hydrogen storage technologies. Finally, the fabricated carbon fiber/MnO₂ composites were applied successfully as working electrodes for analysis of the [Fe(CN)₆]^3−/4− redox system in aqueous KCl solutions. Full article

Background/Objectives: Chemical methods for quantifying resistant starch (RS) in rice are labor-intensive, costly, and lack high repeatability, creating a bottleneck in breeding. This study aimed to develop specific, codominant molecular markers for the Wx gene to enable rapid and accurate genotype screening for RS content, thereby accelerating the development of high-RS rice varieties. Methods: Based on sequence alignment of the Wx gene in rice varieties with divergent RS content, a key single-nucleotide polymorphism was targeted. Two sets of tetra-primer amplification refractory mutation system polymerase chain reaction (ARMS-PCR) markers, T-Wx9-RS1 and T-Wx9-RS2, were designed. These markers were used to genotype diverse rice varieties and F₄ segregating populations, with results validated against standard chemical assays. Results: Sequence analysis identified a critical T → C base mutation at position 202 of the ninth exon in high-RS varieties. The developed ARMS-PCR markers successfully and consistently distinguished all three possible genotypes (homozygous mutant, homozygous wild-type, and heterozygous). The genotyping results showed complete concordance with the phenotypes determined by chemical methods. Conclusions: The developed molecular markers, T-Wx9-RS1 and T-Wx9-RS2, provide a rapid, reliable, and cost-effective tool for marker-assisted selection of high resistant starch content in rice. Their implementation can significantly enhance screening efficiency and expedite the breeding pipeline for novel, nutritionally improved rice cultivars. Full article

Polyethylene terephthalate (PET) recycling technology has developed into a mature system, providing a key paradigm for the circular utilization of polyester waste. Its pathways are primarily divided into mechanical recycling and chemical recycling. Mechanical recycling converts waste PET into rPET through physical processes such as efficient sorting, deep cleaning, and melt extrusion. However, the resulting product often faces issues of decreased intrinsic viscosity and thermal oxidative degradation. Chemical recycling, particularly depolymerization techniques like saccharification, hydrolysis, and methanolysis, can reduce PET waste back to monomers. After purification, these monomers can be repolymerized into virgin-quality PET, achieving a closed-loop cycle. However, this approach faces challenges related to cost and process complexity. Against this backdrop, this paper further explores potential recycling methods for polyethylene terephthalate-1,4-cyclohexanedimethyleneterephthalate (PETG). This paper argues that the experience of PET recycling provides a crucial foundation for addressing PETG challenges but is not a direct solution. Future development directions include: developing intelligent sorting technologies, creating highly efficient selective catalysts to optimize depolymerization reactions, and other initiatives. These measures are essential for establishing an efficient recycling system for complex polyester waste. Full article

A series of reduced graphene oxide–calcium sodium aluminosilicate (rGO-CSA) composites with various rGO/CSA weight ratios (i.e., rGO/CSA 1/2.5, 1/5, 1/10, and 1/15) were successfully synthesized via hydrothermal reaction of CSA particles and GO nanosheets. The chemical compositions and morphology of as-synthesized rGO-CSA composites were characterized by XRD, SEM, BET and FTIR. Results from SEM revealed that CSA particles were deposited on the surface of rGO nanosheets resulting in rGO-CSA nanocomposites. N₂-BET results showed that rGO-CSA4 composites with an rGO/CSA loading ratio of 1/15 showed a high specific surface area of 824.7 m²/g, which is higher than that of raw rGO (370.7 m²/g) and CSA (719.8 m²/g) materials. According the BET and SEM, it can be confirmed that the combination of rGO with CSA can reduce stacking during the drying process of rGO. The as-prepared rGO-CSA nanocomposites exhibited an excellent performance in the adsorption of methylene blue (MB). The rGO-CSA3 material exhibits an MB saturation adsorption capacity of 66.3 mg/g. Since rGO is the only adsorption-active material in the rGO-CSA3 composite, the rGO (9.09 wt%) in rGO-CSA exhibited an MB saturation adsorption capacity of 729.4 mg/L after content correction, which is far greater than the value of raw rGO material. The rGO-CSA3 composites showed superior adsorption efficiency of MB, mainly due to CSA particles effectively reducing rGO nanosheets stacking during the drying process. Full article