Abstract: As mining depth increases, roadway surrounding rock in underground coal mines is increasingly prone to severe deformation and failure. In particular, the mechanical behaviour of weak, soft rock masses is highly heterogeneous and difficult to control, making reliable stability management challenging. Grouting reinforcement has therefore become an effective intervention for improving the integrity and load-bearing capacity of the surrounding rock. With the growing complexity of engineering–geological conditions, grouting materials are required to deliver rapid setting and early strength while maintaining anti-dispersion performance and long-term durability. To meet the demand for fast solidification and efficient support under deep-mine conditions, this study develops an ultrafine silicate cement–based grout incorporating an expansive agent (8%), a water-reducing agent (0.35%) and a setting accelerator (1.0–3.5%), with the water-to-cement ratio fixed at 0.40. Using a suite of macro- and micro-scale characterization methods, we quantify how accelerator dosage governs slurry workability, mechanical performance and the microstructure of hardened grout, and we elucidate the associated hydration mechanisms. Increasing accelerator content markedly shortened the setting time by 61.54–97.50% (relative to the control) but reduced flowability, whereas both compressive and flexural strengths exhibited a non-monotonic trend, increasing initially and then declining at higher dosages. An accelerator dosage of 2.5% yielded the best overall performance, increasing 3-day compressive and flexural strengths by 14.40% and 125.12%, respectively, and improving 28-day compressive strength by 14.76%. Microstructural evidence further indicates that an appropriate accelerator dosage promotes a denser and more homogeneous hydration-product network, thereby enhancing structural stability. Overall, maintaining the accelerator dosage within 2.0–2.5% provides an optimal balance between setting … Read More

Abstract: The ocean contains abundant uranium resources. From the perspectives of resource utilization and ecological environmental protection, uranium extraction from seawater represents a highly promising method for uranium resource regeneration. This approach holds significant potential for the advancement of nuclear power and the broader application of reliable energy. Covalent organic frameworks (COFs) are ideal materials for extracting U(VI) ions from seawater due to their inherent porosity, robust skeletal structure, chemical stability, and good structural regularity. This paper reviews recent progress in the efficient preconcentration and separation of U(VI) from seawater through adsorption and photocatalysis. The current developments and potential of U(VI) extraction using functional COFs are also discussed. Lastly, this review highlights the opportunities and challenges associated with COF-based seawater uranium extraction, offering insights into its future development prospects. This work aims to deepen readers’ understanding of the key technologies involved in COFs for seawater uranium extraction, and to identify more efficient and environmentally friendly COF-based materials, thereby supporting the growth of the nuclear power industry. Read More

Abstract: To address the precise measurement of epitaxial layer thickness in silicon carbide materials, this paper constructs a dual-beam epitaxial layer thickness calculation model based on infrared interferometry. Derived from the fundamental optical principle of optical path difference, this model considers only the scenario where interference occurs due to a single reflection and transmission at the epitaxial layer-substrate interface. First, the optical path difference Δ is determined through geometric optical path analysis and Snell's law. Considering that the refractive index of the epitaxial layer is not a constant and exhibits dispersion effects, the refractive index function of the epitaxial layer is established using the Cauchy dispersion formula. Subsequently, under the condition of half-wave loss, the effective optical path difference formula is derived by calculating the optical path differences of reflected light 1 and reflected light 2. By combining the constructive interference condition with the effective optical path difference formula, a quantitative relationship was ultimately derived between the epitaxial layer thickness and the interference order, wave number, incident angle, and refractive index. This model provides a rigorous mathematical framework for establishing fundamental geometric relationships and incorporating dispersion characteristics in epitaxial layer thickness measurements. Read More

Abstract: Covalent organic frameworks (COFs) are a novel class of materials held together by covalent bonds, sparking a research boom in recent decades. However, due to the challenges involved in research, studies on COFs have often focused on two-dimensional covalent organic frameworks (2D COFs), while research on three-dimensional covalent organic frameworks (3D COFs) which are more difficult to prepare remains in its initial stages. 3D COFs offer a novel material platform for photocatalysis due to their tunable frameworks, adjustable pore channels, and abundant organic functionalization sites. This paper first focuses on the synthesis methods of 3D COFs. Subsequently, characterization techniques for 3D COFs are introduced. Then, the applications of 3D COFs in electrocatalysis are highlighted. Finally, the challenges and prospects for the future development of 3D COFs are discussed. Read More

Abstract: The escalating global urgency for clean water and critical mineral recovery necessitates separation technologies that transcend the inherent permeability-selectivity trade-offs of conventional polymeric membranes. Covalent Organic Frameworks (COFs), distinguished by their precise reticular chemistry, tunable pore architectures, and modular functionality, have emerged as a transformative platform for next-generation ion separation. This review systematically evaluates recent breakthroughs in the engineering of COF-based membranes, focusing on the nexus between fabrication strategies and application performance. We critically examine diverse synthesis methodologies, including interfacial polymerization, in situ growth, and electrophoretic deposition, highlighting how these techniques control membrane crystallization and defect minimization. Furthermore, the review details the deployment of these materials across three pivotal sectors: seawater desalination, where they achieve superior salt rejection; lithium resource extraction, enabling high-precision Li+/Mg2+ differentiation; and the purification of drinking water from heavy metals and radionuclides. The discussion concludes by identifying the critical bottlenecks in scalability and long-term stability that must be addressed to transition COF membranes from laboratory prototypes to industrial implementation. Read More

Abstract: With the increasing demand for lightweight and high-strength and toughness materials in the automotive, construction machinery, and other fields, quenched and partitioned (Q&P) steel has become a research hotspot due to its excellent strength-ductility matching characteristics [1]. QP1500 high-strength quenched and partitioned steel undergoes welding processing in engineering applications, and the welding method significantly affects its microstructural stability and resistance to hydrogen embrittlement, which is crucial for the safety of component service [2]. This study takes QP1500 steel as the object to explore its microstructure and mechanical properties, focusing on analyzing the regulation of microstructural evolution and hydrogen embrittlement sensitivity by tailor welding and L-bend welding [3]. By combining microscopic analysis methods such as optical microscopy (OM) and scanning electron microscopy (SEM) with tensile testing, slow strain rate testing (SSRT), and hydrogen permeation testing, the process-microstructure-property correlation is revealed. The results show that high power promotes martensitic grain refinement, enhancing tensile strength and elongation. The hardness of the welding start, middle, and end surfaces exhibits the same trend. The end surface hardness is relatively high, showing a gradual upward trend. The hardness of the welding start surface is the lowest. This study provides theoretical and technical support for the optimization of engineering welding processes and hydrogen embrittlement resistance design of QP1500 steel, which is of great significance for promoting the industrial application of high-strength Q&P steel [4]. Read More