Bulk SS304 polycrystalline materials with ultrafine microstructures were prepared via a high-pressure self-heating melting and quenching method. Analyses of phase composition, grain size and microstructure were performed using metallographic analysis, X-ray diffraction, Rietveld refinement and transmission electron microscope (TEM). The effects of pressure and cooling rate on the solidification of SS304 were analyzed. Mechanical property test results show that, compared with the as-received sample, the hardness and the yield strength of the pressure-quenched (PQ) samples were greatly increased, the ultimate tensile strength changed minimally, and the elongation rate became small, primarily due to the large density of dislocations in the sample. The high-pressure self-heating melting and quenching method is an exotic route to process a small piece of steel with moderate properties and ultrafine microstructure.

The recent development of SERS substrates based on irregular nanostructures for directly molecule recognition has aroused increasing attention. By combining the irregular flake-like nanostructures of mantis wings, high SERS performance of Ag nanofilms, and the chemical stability of Au nanoparticles (NPs), an ultra-sensitive and flexible SERS substrate based on Au NPs functionalized Ag nanofilms-mantis wings (Au-Ag-M.w.) hybrid system is successfully fabricated. When 4-aminothiophenol is selected as the probe molecule, the limit of detection (LOD) is as low as 10⁻¹³ M and the relative standard deviation (RSD) is lower than 7.15%. This novel SERS platform exhibits high SERS performance in terms of sensitivity, reproducibility and practicability mainly because there are high-density and multi-level “hot spots” in the appropriate nanogaps. Meanwhile, it also systematically compares the differences of the SERS performance of Cu and Ag decorated M.w. hybrids and how these differences can alter their response. Moreover, the proposed substrate is employed to rapidly detect the pesticide residues on apple peels and the LOD for cypermethrin is estimated at 10⁻¹⁰ mg/mL. Therefore, this novel SERS substrate has great potential in rapid sampling of pesticide residues on real samples and expands the investigation to other natural materials for fabricating various SERS platforms.

Compared with single-metal materials, bimetallic materials exhibit superior oxidation resistance and stability. The Surface-enhanced Raman Scattering (SERS) performance can be effectively modulated by adjusting the concentration of the precursors. Herein, Fe₃O₄@EDTA@Ag-Cu NPs were successfully synthesized, the SERS performance of the substrate was significantly enhanced by modulating the concentration of the silver and copper precursors. The results indicated that the SERS sample prepared by mixing the dispersion of Fe₃O₄@EDTA@Ag-Cu NPs with Rhodamine 6G(R6G) solution at a 1:2 volume ratio, achieved a detection concentration as low as (1.0 ± 0.2) × 10⁻¹⁰ M for R6G. Furthermore, the substrate demonstrated high sensitivity, uniformity, temporal stability, reproducibility, and the capability for the rapid detection of benzimidazole in strongly alkaline conditions.

In this paper, VGCF/304L stainless steel composite was prepared using spark plasma sintering (SPS) with 2 vol.% nanocarbon fiber. Then, phase content, grain size, and mechanical properties were evaluated. The results showed that the Vickers hardness of 304L sintered stainless steel and the composite prepared by SPS under the condition of 950 °C for 10 min were 244 HV and 310 HV, respectively, which is an increase of about 27.0%. The yield strength ascended from 587.1 MPa to 890.2 MPa, registering an increase of approximately 51.6%. Concurrently, the ultimate tensile strength rose from 821.5 MPa to 1064.7 MPa, with an approximate increase of 29.6%. This method for improving the mechanical properties of stainless steel is expected to be widely adopted for producing fiber-reinforced metal matrix composites with excellent overall performance.

As a promising cathode material for magnesium-ion batteries, MgMn ₂ O ₄ has been increasingly studied due to its high theoretical capacity and low cost. However, the inherent Jahn–Teller distortion of Mn ³⁺ ions compromises its cycling stability. In this study, nanoscale single-phase MgMn ₂ O ₄ and MgMn _1.5 Fe _0.5 O ₄ cathode materials were synthesized by Pechini method. The crystal structure of MgMn _1.5 Fe _0.5 O ₄ has been systematically analyzed, along with its impact on electrochemical properties. Fe‑doping induces a phase transformation from tetragonal spinel to cubic spinel in MgMn ₂ O ₄ structure. X‑ray Rietveld refinement combined with first-principles calculations reveal that Fe occupies octahedral sites in the Fe-doped structure, accompanied by partial inversion occupancy. During this process, tetrahedral Mg ²⁺ and octahedral Mn ³⁺ sites undergo exchange, thereby stabilizing the cubic phase. This structural modification effectively mitigates Jahn–Teller distortion, enhancing electrochemical cycling stability and Mg ²⁺ diffusion kinetics. After 100 cycles at 200 mA g ^–1 , MgMn _1.5 Fe _0.5 O ₄ exhibits an outstanding capacity retention of 90% with a specific discharge capacity of 126.6 mA h g ^–1 .