Search Results (84)

The demand for high-nitrogen austenitic stainless steel (HNASS) powders has become increasingly urgent due to the rapid development of advanced manufacturing processes. However, it still remains a challenge to accurately control the nitrogen content and its chemical state. In this work, an innovative process combining high-pressure metallurgy and solid-state powder nitriding is proposed to prepare ultra-high nitrogen austenitic stainless steel powders. The prepared powders not only exhibit fine austenite grains, but also achieve a high nitrogen content of up to 5.63 wt.% at 1000 °C, 2.5 h, and 2.5 MPa. The results demonstrate that the phase composition of the powders, as well as the size and distribution of nitrides can be effectively regulated by carefully controlling the key processing parameters including temperature, time and pressure. Nitrogen is predominantly uniformly distributed as solid solution, with minor nanoscale nitride precipitates. XPS analysis of the powder surface indicates that the peak area ratios of N1s (N 1s core-level) in the form of solid solution and nitrides are ~82.95% and ~17.05%, respectively. And the peak area ratios of N1s at different depths of the powder do not show significant changes. Furthermore, the high-pressure nitriding mechanism reveals that the synergy between a high-pressure nitrogen atmosphere and solid-state nitriding enhances nitrogen diffusion flux and increases nitride nucleation density, enabling precise control of nitrogen content and precipitate size. Moreover, the high-pressure nitriding process can effectively keep nitrogen in a solid solution, prevent the precipitation of coarse nitrides, and consequently improve the quality of the powders. This research provides in-depth guidance and insights into the design and preparation of HNASS powders. Full article

X ray photoelectron spectroscopy (XPS) is a key technique routinely employed for the chemical analysis of alloy surfaces, enabling precise nanoscale characterization of near surface elemental composition and chemical states. This review outlines the fundamental principles of XPS, typical data analysis workflows, and critical analytical considerations specific to alloy systems. Given the propensity for oxidation, multicomponent nature, and heterogeneous phase characteristics of alloys, standardized protocols are reviewed for sample preparation, binding energy calibration, peak fitting, quantitative analysis, and depth profiling. For conductive alloys, calibration using the Fermi edge or gold reference standards is specified, and the use of Auger parameters is highlighted to improve the reliability of chemical state identification. This article also systematically summarizes applications of XPS in corrosion protection, high temperature oxidation, surface modification, phase transformation, and failure analysis. It is emphasized that near surface chemical information must be validated in combination with bulk phase, microstructural, and electrochemical characterization to rationally establish relationships between surface chemistry and macroscopic performance. Finally, recent advances in near ambient pressure, in situ, high resolution, and intelligent XPS techniques are reviewed, providing a standardized reference and technical support for alloy research. Full article

We report the synthesis of Fe/N/C ORR electrocatalysts by an original collinear CO₂ laser pyrolysis of liquid aerosol droplets in various configurations and compared them to a catalyst synthesized in the classical perpendicular one. While the precursors were always injected at the bottom side of the reactor, two collinear configurations of the laser entry into the reactor are considered: by the Top Side (T.S.) or by the Bottom Side (B.S.). The two corresponding catalysts sets show significant different ORR performances. An in-depth XPS analysis and fitting of the N1s spectra allowed for drawing the ORR performance as a function of FeN_x sites components. An original approach considering the energy delivered to a quantity of precursors in J.g⁻¹, linked to the flame temperature feature, evidenced very different conditions for perpendicular CO₂ laser pyrolysis and each of the two collinear configurations. This mass-weighted energy delivered in the classical perpendicular configuration is too low to allow for the formation of FeN_x sites and the resulting ORR performance is extremely poor, suggesting a marginal role of nitrogen species without interaction with iron atoms. In contrast, the delivered mass-weighted energies are sufficient in both collinear configurations to produce FeN_x sites. The ORR performance for catalysts produced in these both configurations is positively correlated with the amount of energy deposited on the precursors. The ORR performance in the T.S. laser configuration is positively correlated to the amount of FeN_x sites. The best performing catalysts obtained in the B.S. configuration show an opposite variation. These trends, and the ORR performance degradation of B.S. catalysts under prolonged chronoamperometry are discussed in light of the effect of temperature on the formation of the various kind of FeN_x sites. A tentative explanation is given, considering that N1s XPS fitting with a single FeN_x component may hinder the fact that Pyridinic sites components may contain a part of FeN_x sites, as suggested by theoretical calculation from the literature. The best catalysts obtained in this work by collinear configuration show similar performances to those obtained by double stage perpendicular pyrolysis previously reported with an ORR onset potential of ~860 mV. Full article

Although the corrosion properties of Ti-6Al-4V have been widely studied, the differences in passive film evolution and corrosion mechanism between wrought and SLMed Ti-6Al-4V in acidic service environments are still unclear. In this work, the corrosion behaviors of wrought and selective laser melting (SLMed) Ti-6Al-4V alloys in 0.05 mol/L H₂SO₄ solution were systematically investigated using electrochemical impedance spectroscopy, potentiodynamic polarization curves, Mott–Schottky analysis and XPS depth profiling. Wrought and SLM-fabricated Ti-6Al-4V were selected to reveal the effects of typical forming processes on corrosion resistance, considering their wide applications and distinct microstructures. Electrochemical results demonstrate that the wrought alloy exhibits a higher polarization resistance, a thicker passive film, and a lower corrosion current density, corresponding to superior corrosion resistance. Mott–Schottky analysis reveals that the passive films formed on both alloys show n-type semiconductor characteristics, while the wrought alloy possesses a lower carrier concentration, fewer defects, and a more compact film structure. XPS depth analysis indicates that the content of TiO₂ in the passive films decreases with increasing etching depth, accompanied by an increase in TiOOH, TiO, and metallic Ti. Full article

Boron coatings were deposited by RF magnetron sputtering in an Ar atmosphere at a constant power of 80 W, varying the working pressure in the 0.6–5 Pa range. Plasma diagnostics were performed by means of a Langmuir probe to determine the electron temperature and electron density under different operating conditions. Within the investigated pressure range, the deposition rate remained nearly constant, whereas a significant decrease in coating mass density was observed with increasing pressure. The coatings display a columnar structure at all investigated pressures, with no significant differences in bulk morphology. Pressure primarily affects the surface features, leading to an increase in the density, lateral dimensions, and height of surface agglomerates with increasing pressure. Compositional analysis by EDX revealed a substantial oxygen incorporation in the films, with the lowest oxygen content (~11 at.%) measured for the coating deposited at 0.6 Pa. XPS depth profiling confirmed the presence of oxygen and evidenced the formation of boron oxide species, while the boron concentration exceeded 80 at.% in all samples. These results highlight the strong sensitivity of boron film density and oxygen uptake to sputtering pressure. Full article

Chromium (Cr) is a common heavy-metal pollutant that poses a significant threat to both the environment and human health. Herein, a novel strain Lysinibacillus capsici FPHNCRA4-48, with a high Cr tolerance and removal performance, was isolated from Cr-contaminated plant water in Changde, Hunan Province. Structural characterization and proteomic analyses were performed to investigate the Cr removal performance and molecular mechanism of L. capsici FPHNCRA4-48. FPHNCRA4-48 can effectively remove more than 99% of the Cr(VI) at an initial concentration of 1000 μmol/L. The FTIR, 3D-EEM, and XPS results revealed that -OH, -NH₂, and -CO-NH₂ derived from extracellular polymeric substances (EPSs) were mainly involved in Cr(VI) removal. Interestingly, the protein content in the EPS increased significantly (1.32-fold) after exposure to Cr(VI). Moreover, proteomic analysis revealed that genes (rpmA, rpmI, rpmC, rplI, rpmD, deoB, deoC) related to translation and carbohydrate metabolism, and genes (pyk, icd, rpiB, eno) related to amino acid biosynthesis were all significantly up-regulated, suggesting that these pathways related to protein synthesis in L. capsici FPHNCRA4-48 were activated under Cr(VI) stress. Finally, KEGG ribosome pathway enrichment occurred. These data highlight the importance of microbial EPSs in bioremediation in Cr-polluted environments. This study identified highly efficient Cr(VI)-removing bacterial strains and conducted an in-depth analysis of the removal mechanism of their extracellular polymeric substances (EPSs), thereby providing theoretical foundations and technical support for the biological remediation of Cr(VI)-contaminated water bodies. Full article

This study systematically investigates the influence of short carbon-fiber (SCF) content on the mechanical, thermal, and tribological properties of self-lubricating polyphenylene sulfide (PPS) composites filled with PTFE and MoS2, addressing the critical need for high-wear resistance in Carbon-Fiber-Reinforced Thermoplastic (CFRTP) structural applications. The results identified 10 wt% SCF as the optimal content that achieved the best balance between load-bearing capacity and friction performance. The coefficient of friction μ and wear amount were reduced by 29.28% and 29.29%, respectively, compared to the PPS/PTFE/MoS2 composite material without SCF, and by 14.67% and 20.75%, respectively, compared to the material with excessive SCF filling (20 wt%). Finite-Element Analysis-Representative Volume Element (FEA-RVE) reveals the mechanism by which excessive content of SCF at the microscopic level leads to a slight decrease in mechanical properties. Critically, the tribological performance exhibited a discrepancy with bulk mechanical properties: above 15 wt% SCF, the wear rate worsened despite high mechanical strength, revealing that increased fiber agglomeration and micro-abrasion effects were the primary causes of performance deterioration. Further in-depth XPS analysis revealed a synergistic lubrication mechanism: In the optimal sample, an ultra-dense PTFE transfer film was formed to mask the underlying MoS2. This masking, coupled with the high surface activity of MoO3 particles leads to stronger physicochemical interactions with the polymer matrix, ensures the exceptional durability and stability of the tribo-film. This research establishes a complete structure–performance relationship by integrating mechanical, thermal, and tribo–chemical mechanisms, offering critical theoretical guidance for the design of next-generation high-performance self-lubricating CFRTPs. Full article

Urban floods are becoming increasingly frequent and severe, highlighting the need for real-time information that supports safe evacuation decision-making. This study proposes and validates an unmanned aerial vehicle (UAV)-based methodology for real-time urban flood monitoring using an actual flood event caused by Typhoon Hinnamnor at the Seondeok Intersection in Gyeongju, Republic of Korea. The method comprises three simple steps: (1) collecting UAV images and data; (2) generating spatial and terrain information through photogrammetry; and (3) estimating flood extent, depth, and volume using GIS-based analysis. A total of 796 UAV images were processed, yielding a flooded area of 3847.36 m², a flood volume of 13,895.13 m³, and a maximum depth of 0.75 m. To assess performance, UAV-derived results were compared with XP-SWMM simulation outputs. Significant discrepancies were observed in flood extent, inundation volume, and flood persistence, indicating that hydrological models may not fully capture localized drainage failures or site-specific conditions in urban environments. These findings demonstrate that UAV-based monitoring provides a more accurate representation of actual flood and can supply high-resolution, rapidly obtainable information essential for real-time evacuation. This study provides empirical evidence of UAV applicability during the flood event itself and highlights its potential to enhance disaster-response capability, improve decision-making, and strengthen the resilience and sustainability of flood-prone urban areas. Full article

Scandium (Sc)-doped aluminum nitride (AlN) thin films are critical for high-frequency, high-power surface acoustic wave (SAW) devices. A composite Sc doping strategy for AlN thin films is proposed, which combines magnetron sputtering pre-doping with post-doping via ion implantation to achieve gradient doping and tailor microstructural characteristics. The crystal structure, surface composition, and microstructural defects of the films were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). Results indicate that the Sc content in pre-doped ScAlN films was optimized from below 10 at.% to above 30 at.%, while the films maintained a stable (002) preferred orientation. XPS analysis confirmed the formation of Sc-N bonds, and EDS mapping revealed a gradient distribution of Sc within the subsurface region, extending to a depth of approximately 200 nm. High-resolution TEM revealed localized lattice distortions and surface amorphization induced by ion implantation. This work demonstrates the feasibility of ion implantation as a supplementary doping technique, offering theoretical insights for developing AlN films with high Sc doping concentrations and structural stability. These findings hold significant potential for optimizing the performance of high-frequency, high-power SAW devices. Full article

The risk of urban flooding has escalated with increasing rainfall intensity and the expansion of impervious surfaces. While commercial models such as XP-SWMM provide reliable hydraulic analyses, their closed-source structure limits transparency and integration with external tools. In contrast, the Grid-Based Urban Drainage System Analysis Model (GUDS), developed on the Weighted Cellular Automata 2D (WCA2D) framework, offers greater flexibility for process verification and coupling with platforms such as GIS and spreadsheets. This study presents a comparative assessment of numerical stability and velocity estimation schemes between XP-SWMM and GUDS. Moving beyond previous validation-focused studies, it quantitatively examines how algorithmic formulations—particularly in flow velocity computation and numerical treatment—affect inundation propagation and model stability under varying topographic conditions. Results demonstrate that XP-SWMM yields higher analytical precision but is prone to numerical instability on steep slopes, whereas GUDS maintains stable simulations due to its simplified water-level-difference approach, albeit with reduced responsiveness to rapidly changing flows. The differences in maximum inundation depth, inundation area, and propagation speed were relatively minor—approximately 11.6%, 10.7%, and 9.2% on average, respectively. This work provides a novel quantitative perspective on the trade-offs between precision and stability in urban flood modeling, highlighting GUDS’s robustness and practical applicability as an open and extensible alternative to conventional equation-based models. Full article

Duolang sheep, a meat–fat dual-purpose breed indigenous to Xinjiang, China, has been cultivated traditionally by the local Uyghur people for its prolificacy and precocious sexual maturity, while little research on the population structure and trait inheritance characteristics of Duolang sheep is available. This study employed whole-genome resequencing data from a cohort of 60 Duolang sheep to dissect their genetic population structure and genes related to reproductive traits. A total of 1565 Gb of high-quality data with an average depth of 14.06× was generated. After SNP calling and quality control, 31,300,060 SNPs were identified. Following linkage disequilibrium (LD)-based pruning, a total of 4,479,177 high-quality SNPs were retained for subsequent analyses. Based on these SNPs, the internal genetic structure of the Duolang sheep population was elucidated, with 14 kinship outliers detected through principal component analysis (PCA). Furthermore, LD decay analysis revealed that the r² declined below 0.1 at approximately 10 kb, indicating a relatively low level of selection pressure in the population. Within the population, Tajima’s D and iHS methods detected 517,218 and 82,534 candidate SNPs under selection, respectively, with 24,453 SNPs overlapping between the two methods. By splitting Duolang sheep into single-lamb (n = 29) and multiple-lamb (n = 12) subgroups according to litter size, 267,654 SNPs were identified by XP-CLR, while 184,179 SNPs suffering from selection were detected by F_ST and 62,150 by XP-EHH. Functional enrichment analysis of selected genes reveals the selection directions (domestication, growth, and reproduction) and related candidate genes in the Duolang sheep population, including ESRRA, ESRRB, OXT, FSHR, ESR2, GNRHR, and BMPR1B. This study provides the first comprehensive genomic landscape of Duolang sheep, elucidating genetic signatures of its adaptive traits. Full article

The surface of chalcopyrite was studied by XPS characterization for an unleached chalcopyrite, and, after being leached in an alkaline oxidant medium at room temperature, pH 12.5, and [ClO⁻] 0.34 M, the reaction of enargite presented high selectivity with respect to chalcopyrite, allowing the removal of arsenic from copper concentrates with high arsenic content prior to smelting. Based on the XPS analysis, the original chalcopyrite is composed of a combination of its constituents in different oxidation states, and chalcopyrite has the following stoichiometric formula: Cu(I)_0.85Cu(II)_0.15Fe(II)_0.65Fe(III)_0.35S²⁻_1.5S₂²⁻_0.17S_n0.08²⁻. The unleached chalcopyrite on its surface presents an iron deficiency, which raises the ratio Cu/Fe up to 2, reaching the chalcopyrite Cu/Fe rate in the fifth cycle. The Cu/S ratio of chalcopyrite, 0.5, remains constant at the surface as after the peeling. Surface sulfur shows a decrease in monosulfides, increasing the S_n²⁻/S²⁻ y S₂²⁻/S²⁻ ratio. Chalcopyrite leached with ClO⁻/OH⁻ media generates surface layers with the following intermediate products: Chalcopyrite → CuFe_1-xS₂/CuS_n/Fe³⁺ -OH → Fe³⁺-OH/CuO/SO₄²⁻. Neither sulfur intermediates nor oxidized final products are passivating, allowing the chalcopyrite transformation to progress in depth with increasing reaction time. Full article

Background/Objectives: Magnetic drug targeting (MDT) using polyethene glycol (PEG)-coated magnetoresponsive nanoclusters (MNCs) can localize therapeutics, but washout from high-shear arterial flow limits efficacy. This study assesses how PEG molecular weight influences MNC deposition and washout resistance under a pulsatile flow. Methods: Magnetite MNCs were synthesized via solvothermal polyol reactions and PEGylated with PEG-2000, PEG-6000, or PEG-10,000. Characterization included TEM, DLS, zeta potential, FTIR, TGA, XPS, magnetic analysis, and rheology. In vitro assays used a 3 mm diameter glass phantom with pulsatile flow (0.10–0.45 m/s, 1 Hz) and a rectangular NdFeB (N35) permanent magnet (30 × 20 × 20 mm, 0.45 T) positioned 11 mm from the vessel wall. Washout performance was quantified by obstruction degree (OD), magnet coverage degree (MCd), washout degree (WD), washout rate constant (k_out), and half-life (τ₁/₂). Results: MNC-6000 balanced magnetic responsiveness (Ms = 72 emu/g), colloidal stability (ζ = +13.1 mV), and hydrodynamic size (535 nm), yielding superior retention (MCd = 72.3%, OD = 19.6%, WD = 17.9%, τ₁/₂ = 6.93 min). MNC-2000 exhibited faster loss (k_out = 0.14 min⁻¹, τ₁/₂ = 4.95 min), while MNC-10,000 produced higher OD (≈53%) with embolic risk. Magnetic mapping indicated vessel wall thresholds of B ≥ 0.18 T and ∇B ≥ 10 T/m for stable capture. Limitations: Limitations of this work include the use of a single-magnet geometry, an in vitro phantom model without endothelial biology, and a maximum targeting depth of ~12–14 mm. Conclusions: The PEG molecular weight modulates MDT performance through its effects on nanocluster stability, deposition morphology, and washout kinetics. The proposed OD, MCd, and WD metrics provide clinically relevant endpoints for optimizing MDT nanoparticle design and magnet configurations. Full article

Speed is not only the primary objective of racehorse breeding but also a crucial indicator for evaluating racehorse performance. This study investigates a newly developed racehorse breed in China. Through whole-genome resequencing, we selected 60 offspring obtained from the crossbreeding of Thoroughbred horses and Xilingol horses for this study. This breed is tentatively named “Grassland-Thoroughbred”, and the samples were divided into two groups based on racing ability: 30 racehorses and 30 non-racehorses. Based on whole-genome sequencing data, the study achieved an average sequencing depth of 25.63×. The analysis revealed strong selection pressure on chromosomes (Chr) 1 and 3. Selection signals were detected using methods such as the nucleotide diversity ratio (π ratio), integrated haplotype score (iHS), fixation index (Fst), and cross-population extended haplotype homozygosity (XP-EHH). Regions ranked in the top 5% by at least three methods were designated as candidate regions. This approach detected 215 candidate genes. Additionally, the Fst method was employed to detect Indels, and the top 1% regions detected were considered candidate regions, covering 661 candidate genes. Functional enrichment analysis of the candidate genes suggests that pathways related to immune regulation, neural signal transmission, muscle contraction, and energy metabolism may significantly influence differences in performance. Among these identified genes, PPARGC1A, FOXO1, SGCD, FOXP2, PRKG1, SLC25A15, CKMT2, and TRAP1 play crucial roles in muscle function, metabolism, sensory perception, and neurobiology, indicating their key significance in shaping racehorse phenotypes. This study not only enhances understanding of the molecular mechanisms underlying racehorse speed but also provides essential theoretical and practical references for the molecular breeding of Grassland-Thoroughbreds. Full article

This study evaluates the wear and corrosion resistance of the Cu-50Ni-5Al alloy reinforced with CeO₂ nanoparticles for potential use as anodes in molten carbonate fuel cells (MCFCs). Cu–50Ni–5Al alloys were synthesized, with and without the incorporation of 1% CeO₂ nanoparticles, by the mechanical alloying method and spark plasma sintering (SPS). The samples were evaluated using a single scratch test with a cone-spherical diamond indenter under progressive normal loading conditions. A non-contact 3D surface profiler characterized the scratched surfaces to support the analysis. Progressive loading tests indicated a reduction of up to 50% in COF with 1% NPs, with specific values drop-ping from 0.48 in the unreinforced alloy to 0.25 in the CeO₂-doped composite at 15 N of applied load. Furthermore, the introduction of CeO₂ decreased scratch depths by 25%, indicating enhanced wear resistance. The electrochemical behavior of the samples was evaluated by electrochemical impedance spectroscopy (EIS) in a molten carbonate medium under a H₂/N₂ atmosphere at 550 °C for 120 h. Subsequently, the corrosion products were characterized using X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the CeO₂-reinforced alloy exhibits superior electro-chemical stability in molten carbonate environments (Li₂CO₃-K₂CO₃) under an H₂/N₂ atmosphere at 550 °C for 120 h. A marked reduction in polarization resistance and a pronounced re-passivation effect were observed, suggesting enhanced anodic protection. This effect is attributed to the formation of aluminum and copper oxides in both compositions, together with the appearance of NiO as the predominant phase in the materials reinforced with nanoparticles in a hydrogen-reducing atmosphere. The addition of CeO₂ nanoparticles significantly improves wear resistance and corrosion performance. Recognizing this effect is vital for creating strategies to enhance the material’s durability in challenging environments like MCFC. Full article