Jiuquan Iron & Steel (China)

In view of the depletion of high-grade magnesite resources in China, this study presents a comparative analysis of two industrial fused magnesia products produced via a flotation-fusion route. A low-grade magnesite (DSQLM-3, MgO 41.48 wt.%) was upgraded by reverse flotation to a concentrate (FDSQLM-3, MgO 47.55 wt.%) with >97% SiO2 removal. Two fused magnesia samples (FM-1 from natural high-grade ore DSQLM-1; FFM-3 from concentrate FDSQLM-3) were produced under identical arc-furnace melting (2800 °C, 4 h), followed by natural cooling. Although FFM-3 showed higher MgO (97.61 vs. 97.25 wt.%), its bulk density was comparable to FM-1 (3.45 vs. 3.46 g/cm3). XRD/Rietveld refinement and SEM-EDS indicated that CMS dominated the Ca-silicate assemblage in FM-1, whereas β/γ-C2S was observed in FFM-3, coinciding with a higher CaO/SiO2 (C/S) ratio (2.85 vs. 0.68). Image analysis further showed higher grain boundary microcrack metrics in FFM-3. These observations are consistent with reports in the literature stating that the β → γ transformation of C2S during cooling involves ~12% volume expansion that can contribute to cracking; however, cooling history and composition were not independently controlled in this industrial comparison, so the relationships are interpreted as data-supported associations rather than isolated causality. The results suggest that beneficiation strategies may benefit from managing residual oxide balance (especially C/S ratio) in addition to reducing total impurities. Mechanical and thermomechanical properties were not measured and should be evaluated in future work.

The broadcast nature of wireless channels introduces significant security vulnerabilities in information transmission, particularly when the eavesdropper is close to the legitimate destination. In such scenarios, the eavesdropping channel often exhibits high spatial correlation with, or even superior quality to, the legitimate channel. This makes it challenging for traditional power optimization methods to effectively suppress the eavesdropping rate. To address this challenge, this paper proposes an optimization method for the secrecy capacity of unmanned aerial vehicle (UAV) relaying based on the dynamic adjustment of the power allocation factor. By injecting artificial noise (AN) during signal forwarding and combining it with real-time channel state information, the power allocation factor can be dynamically adjusted to achieve precise jamming of the eavesdropping link. We consider a four-node communication model consisting of a source, a UAV, a legitimate destination, and a passive eavesdropper, and formulate a joint optimization problem to maximize the secrecy rate. Due to the non-convexity of the original problem, we introduce relaxation variables and apply successive convex approximation (SCA) to reformulate it into an equivalent convex optimization problem. An analytical solution for the power allocation factor is derived using the water-filling (WF) algorithm. Furthermore, an alternating iterative optimization algorithm with AN assistance is proposed to achieve global optimization of the system parameters. Simulation results demonstrate that, compared to traditional power optimization schemes, the proposed algorithm substantially suppresses the eavesdropping channel capacity while enhancing transmission efficiency, thereby significantly improving both secrecy performance and overall communication reliability.

In the present contribution, Hot-rolled and annealed ferritic stainless steel T4003 with three distinct Mo contents (0%, 0.1%, and 0.2%) served as the research subject. Weldability tests were implemented by means of gas metal arc welding. Coupled with microstructural characterization, mechanical property assessments, and electrochemical corrosion tests, the regulatory mechanism of Mo on the microstructure and properties of the HAZ was systematically elucidated. Results demonstrate that the influence of Mo content on the evolution of the coarse-grained region structure of heat affected zone becomes significant. The addition of 0.1% Mo refines the grains, increasing the fraction of lath martensite to 70–75% while limiting the maximum width of the coarse-grained zone to 0.64 mm. Meantime, the addition promotes the precipitation of (Nb, Ti, Mo) (C, N) composite carbonitrides, enhancing overall performance through synergistic grain refinement and second-phase strengthening. The sample with 0.1% Mo exhibits an average low-temperature impact energy of 16.3 J at −40 °C, with the highest Vickers hardness in the HAZ, favorable strength–plasticity synergy of the welded joint, and optimal corrosion resistance. The coarse-grained zone of the 0.2% Mo sample is dominated by coarse δ-ferrite and features a larger width, and the HAZ shows inferior mechanical properties and corrosion resistance. The precipitated phases in the 0.2% Mo segregate along the grain boundaries and distribute in a chain-like distribution, exacerbating the deterioration of material properties. These findings provide a technical reference for optimizing the composition design of T4003 ferritic stainless steel and ensuring its safe application in railway freight vehicles.

ObjectiveThe mechanism by which air pollution causes the onset of asthma is complex, and its key targets have not yet been fully identified. In this study, we identified the factors that mediate the relationship between air pollution and asthma.MethodsWe screened overlapping genes related to asthma from the Gene Expression Omnibus (GEO) database by integrating differentially expressed genes (DEGs) and weighted gene co-expression network analysis (WGCNA). To further identify hub genes, we used three machine learning methods: least absolute shrinkage and selection operator (LASSO) regression, support vector machine-recursive feature elimination (SVM-RFE), and random forest (RF). We subsequently analyzed the mediating role of these hub genes in the association between PM2.5 and onset of asthma in a study population consisting of 160 participants with asthma and 160 participants without asthma. The analyses included Pearson correlation analysis, logistic regression analysis, and mediation analysis.ResultsA total of 715 DEGs were identified, and the results of the WGCNA revealed a significant asthma-associated co-expression grey module containing 118 genes. Among these genes, five hub genes (CEBPE, HDC, IRAK3, PRR4, and SOD2) were selected using three different machine learning methods. These genes were confirmed as independent predictors of asthma through multivariate logistic regression analysis and were significantly correlated with PM2.5 levels. Mediation analysis demonstrated that these genes play a mediating role between PM2.5 and asthma onset.ConclusionThis study provided evidence that CEBPE, HDC, IRAK3, PRR4, and SOD2 mediate the connection between PM2.5 and the onset of asthma.

Byakangelicin is a furanocoumarin derived from the roots of Angelica dahurica. It exhibits pharmacological properties, including anti-tumor activity, as well as against liver injury and fibrosis. In this study, Ultra-High-Performance Liquid Chromatography with Q-Exactive Orbitrap Mass Spectrometry technology was employed to investigate the metabolic profile of byakangelicin in rats. Following intragastric administration the suspension of byakangelicin, plasma and tissue specimens were harvested. According to high-resolution extracted ion chromatograms, the metabolites of byakangelicin were identified by comparing accurate mass, diagnostic fragment ions, and chromatographic retention times. Data collection was performed in positive ion mode to facilitate metabolite characterization of byakangelicin. Overall, 46 metabolites were successfully characterised. The primary metabolic pathways included hydroxylation, dehydroxylation, methylation, demethylation, reduction, glucuronidation, glycination, and cysteinylation. This systematic investigation of the metabolic characteristics and pathways of byakangelicin in rats provides a valuable reference for future pharmacodynamic evaluations, pharmacological research, and drug development.