Search Results (775)

Coal gasification slag (CGS) is rich in Si-Al-Ca components and thus has potential for ceramic utilization, but associated heavy metals may pose environmental risks. In this study, CGS from Yili (Xinjiang, China) was used as the major raw material (80 wt%), with clay and waste glass as additives, to prepare ceramsite by firing green pellets (8–12 mm) at 1000–1200 °C. The phase evolution, microstructure, and heavy-metal migration were characterized, and the leaching safety was evaluated. Increasing temperature leads to progressive quartz consumption, enrichment of feldspar-type crystalline phases, and liquid-phase sintering, which together enhance densification. The apparent density and single-particle compressive strength exhibit an “increase-then-decrease” trend with temperature and reach maxima at 1150 °C, where the compressive strength is 15.38 MPa. Heavy-metal behavior is element-specific: As and Zn show stronger volatilization, whereas Mn, Ba, Ni, and Cu are largely retained in the solid phase; Cr shows intermediate, temperature-dependent volatilization. After firing at ≥1150 °C, the leached concentrations of Cr, Mn, Ni, Cu, Zn, As, and Ba under the sulfuric acid–nitric acid test (HJ/T 299-2007) are below the Class III limits of the Chinese Groundwater Quality Standard (GB/T 14848-2017). Considering phase/structure evolution, mechanical performance, and short-term heavy-metal leaching, 1150 °C is identified as the preferred firing temperature in this work. Full article

Beryllium (Be), a critical strategic metal element, is predominantly extracted from beryl, which serves as a key mineral combining significant strategic importance with essential industrial applications. Significant debate remains, however, regarding the mineralogical characteristics and color-causing mechanisms of beryl. In this study, we integrate Electron Probe Microanalysis (EPMA), Fourier transform infrared spectrometer (FTIR), laser Raman spectrometer (LRS), X-ray diffractometer (XRD), and ultraviolet–visible spectrophotometer (UV-VIS) to elucidate the mineralogy and spectral characteristics of pegmatitic beryl from Xinjiang, Northwest China. The results indicate that the beryl mainly presents a yellowish-green color, associated with minerals such as feldspar, quartz, and garnet. The EPMA results confirm the chemical composition of the typical beryl and indicate that the Al content is lower than the theoretical value, reflecting the substitution of Al³⁺. The FTIR shows characteristic vibrations of Si-O tetrahedral groups within the range of 1400~400 cm⁻¹, along with distinct bending and stretching vibration peaks of H₂O molecules observed in the range of 1700~1500 cm⁻¹ and 3500~3800 cm⁻¹, respectively. Combined with spectral analysis, it can be determined that both Type I water and Type II H₂O are present in the samples. Raman spectroscopy reveals that the two distinct peaks of beryl are located at approximately 685 cm⁻¹ (attributed to the stretching vibration of Be-O) and 1067 cm⁻¹ (corresponding to the bending vibration of Si-O), respectively. The XRD analysis shows that the ratio of unit cell parameters c/a of the samples ranges from 0.9950 to 1.0068, and the isomorphous substitution in its structure is mainly manifested as the replacement of octahedral coordination sites by Al³⁺. The UV-VIS shows that Fe³⁺ exhibits a broad absorption band in the range of 200~300 nm, while no obvious absorption peaks are observed in the range of 300~800 nm. The above characteristics indicate that Fe³⁺ has a significant impact on the color of beryl. For green beryl samples, a portion of Fe³⁺ occupies the structural channel sites and interacts with H₂O molecules within the channels, which contributes to the yellowish hue of beryl. Our study highlights crucial data for mineralogical identification, genetic tracing, as well as efficient utilization of beryl resources. Full article

Background: Esophagectomy remains the definitive curative treatment for esophageal cancer but is historically burdened by significant procedure-related morbidity. Anastomotic leakage (AL) is still the “Achilles’ heel” of esophageal surgery, serving as a primary benchmark for surgical quality due to its profound impact on patient recovery, healthcare costs, and long-term oncological outcomes. While surgical expertise and perioperative care have matured, reported AL rates remain persistently high. This necessitates a shift in focus from purely technical modifications toward integrated, data-driven preventive strategies. Purpose: Five years after our initial review, this update synthesizes the rapid evolution in AL prevention. We evaluate the transition from empirical surgical pragmatism to evidence-based protocols, integrating recent breakthroughs in real-time perfusion monitoring, prophylactic endoluminal technologies, and multidisciplinary patient optimization. This work provides a contemporary “roadmap” for navigating the complexities of esophageal reconstruction. Conclusions: The prevention of AL has evolved into a multimodal “bundle” that begins well before the index operation. This review highlights the critical shift toward quantitative perfusion assessment via indocyanine green fluorescence angiography, which is increasingly replacing subjective visual inspection as the standard for anastomotic site selection. We discuss the emerging role of gastric ischemic preconditioning as a biological strategy to enhance conduit vascularity, alongside the paradigm of proactive management using preemptive endoluminal vacuum therapy to mitigate septic sequelae in high-risk cases. Furthermore, we examine technical refinements in conduit construction and conditioning—focusing on the ‘tension-perfusion’ relationship—and the essential role of structured prehabilitation within enhanced recovery after surgery frameworks. While the quality of evidence remains heterogeneous, the move toward standardized reporting and objective monitoring marks a new era of precision in esophageal surgery. Full article

The catalytically supported upgrading of green ethanol and green methanol mixtures can produce higher alcohols, such as iso-butanol, in a sustainable manner. Iso-butanol can be used as a feedstock to defossilize the chemical and transportation sectors. MgO-Al₂O₃ hydrotalcite-based catalysts are a promising option for this purpose. In this paper, samples were synthesized using co-precipitation and urea methods with different Mg/Al molar ratios with Ni acting as the active catalytic component. Thereby, the catalysts synthesized using the urea method exhibited the greatest activity, producing iso-butanol concentrations of up to 170 mmol L⁻¹ at 185 °C, with selectivities towards iso-butanol of 85–89% and a maximum space–time yield of 8.2 mmol g⁻¹ h⁻¹. The most active catalyst among all samples from this paper was characterized by 100% proportions of strong basic and medium acidic catalyst sites and the largest specific surface area. XRD analysis revealed the presence of NiO, MgO and the spinels Al₂NiO₄ and Al₂MgO₄ in both synthesis variants as well as elemental Ni in one sample from the urea synthesis. CO₂-TPD and NH₃-TPD experiments showed the dominance of strong basic and medium/strong acidic catalyst sites in both synthesis pathways. Full article

Binder Jetting 3D Printing (BJ3DP) offers an effective pathway for the rapid fabrication of complex high-entropy alloy (HEA) components. In this study, the macroscopic characteristics, microstructural evolution and mechanical properties of Al_0.5Cr_0.9FeNi_2.5V_0.2 HEA green parts prepared via BJ3DP were investigated under various sintering conditions. Results showed that the relative density of the sintered parts increased significantly with temperature, transitioning from a low density (<90%) at 1300–1330 °C to near-fully dense (~98%) at 1340–1350 °C. Consequently, the mechanical properties were remarkably improved. The yield strength (σ_0.2) increased from 300 MPa to 710 MPa (a 136% increase), and the ultimate tensile strength (σ_b) rose from 310 MPa to 780 MPa (a 148% increase) as sintering temperature rose from 1300 °C to 1350 °C. Microstructural analysis revealed that at lower sintering temperatures, the alloy exhibited high porosity and a non-coherent structure composed of an FCC matrix and Cr-rich BCC phase, with Al/Ni intermetallic compounds distributed around pores. Conversely, at the final sintering stage, pore closure was achieved, and a coherent structure consisting of an FCC matrix and scale-like L1₂ precipitates was formed. Optimal mechanical properties (tensile strength ≥ 700 MPa) were achieved when sintering at 1340 °C, primarily attributed to densification and precipitation strengthening. Full article

Mamluk historiography is predominantly centred on the political actions of the ruling elite, particularly sultans and senior officials, whose careers and decisions are extensively documented in chronicles, biographical dictionaries, and autobiographical writings. In contrast, lower-ranking members of the ruling hierarchy appear only sporadically and occupy a structurally marginal position within historical narratives. Legendary and folkloric traditions are similarly marginalised, typically remaining outside the scope of official historiography and surviving primarily through oral transmission or in sources linked to socially and politically peripheral groups. Although a small number of reports attributed to lower-ranking mamluks are preserved in certain texts, they were largely ignored by Mamluk historians. This article examines Mamluk accounts of the legend of the “Green City” located in Tīh Banī Isrāʾīl (the Wilderness of the Children of Israel) in Sinai. The story is attributed to the Mamluks, who allegedly encountered the city while fleeing to Bilād al-Shām after the assassination of al-Amīr Fāris al-Dīn Aqṭāy by Sultan al-Muʿizz Aybak in 652/1254. Despite its proximity to this major political event, the narrative survives only in brief references by six historians across the entire Mamluk period (648–923/1250–1517). By analysing the transmission and marginalisation of this account, the article argues that the legendary narrative of the Green City offers a revealing case study of how extraordinary desert traditions were selectively incorporated into Mamluk historiography. A microhistorical and critical reading of the story further illuminates the interplay between oral testimony, desert knowledge, and the historiographical practices that shaped the preservation, adaptation, or omission of such narratives. Full article

High-temperature carburization (HTC, 950–1050 °C) has emerged as a pivotal low-carbon, energy-efficient manufacturing technology for gear steels, accelerating carbon diffusion for reducing processing cycles by over 60% while achieving significant energy savings and emission reductions. However, the inherent contradiction between HTC efficiency and microstructural stability, specifically austenite grain coarsening, severely degrades mechanical properties (e.g., strength, toughness, fatigue resistance) and limits widespread application. This review systematically synthesizes recent advances in austenite grain size regulation during HTC of gear steels, focusing on the core scientific framework of “grain coarsening mechanism—regulation strategy—performance enhancement”. It elaborates on thermodynamic and kinetic mechanisms of austenite grain growth, ripening behavior of microalloying precipitates (Nb(C,N), Ti(C,N), AlN, etc.), and their synergistic grain-refining effects. Comprehensive coverage of regulatory strategies (microalloying design, pretreatment technologies, process optimization, and integrated regulation) and characterization techniques is provided, along with a quantitative correlation between grain size, microstructure, and surface performance (wear resistance, corrosion resistance, and fatigue life). Numerical simulation and predictive models (empirical, theoretical, multiphysics coupling, machine learning-based) are critically analyzed, and current challenges (temperature-grain stability trade-off, multifactor synergy understanding, industrial scalability) and future research directions (advanced microalloying systems, intelligent process optimization, cross-scale modeling, green technology integration) are proposed. This review aims to provide theoretical guidance and technical support for optimizing the HTC performance of gear steels, catering to the demands of high-power-density transmission systems in automotive, aerospace, and heavy machinery industries. Full article