Silicon nitride is a bioceramic with great potential, and multiple studies have demonstrated its biocompatibility and antibacterial properties. In this study, silicon nitride was prepared by a microwave sintering technique that was different from common production methods. SEM and pore distribution analysis revealed the microstructure of microwave-sintered silicon nitride with obvious pores. Mechanical performance analysis shows that microwave sintering can improve the mechanical properties of silicon nitride. The CCK-8 method was used to demonstrate that microwave-sintered silicon nitride has no cytotoxicity and good cytocompatibility. From SEM and CLSM observations, it was observed that there was good adhesion and cross-linking of cells during microwave-sintered silicon nitride, and the morphology of the cytoskeleton was good. Microwave-sintered silicon nitride has been proven to be non-cytotoxic. In addition, the antibacterial ability of microwave-sintered silicon nitride against Staphylococcus aureus and Escherichia coli was tested, proving that it has a good antibacterial ability similar to the silicon nitride prepared by commonly used processes. Compared with silicon nitride prepared by gas pressure sintering technology, microwave-sintered silicon nitride has excellent performance in mechanical properties, cell compatibility, and antibacterial properties. This indicates its enormous potential as a substitute material for manufacturing bone implants.

As arsenopyrite is a typical arsenic-bearing sulfide ore, the biooxidation process of arsenopyrite is of great significance for the extraction of gold from arsenic-bearing gold ores and the generation of arsenic-bearing acid mine drainage. During the biooxidation of arsenopyrite, a large amount of arsenic is produced, which inhibits the growth and metabolism of microorganisms and thus affects the extraction of gold from arsenic-bearing gold ores. Therefore, the screening and enrichment of microorganisms with high arsenic resistance have become important aspects in the study of arsenopyrite biooxidation. As described in this paper, through arsenic acclimation, the maximum arsenic tolerance concentration of Acidithiobacillus ferriphilus QBS 3 isolated from arsenic-containing acid mine drainage was increased to 80 mM As(Ⅲ) and 100 mM As(V). Microorganisms with high arsenic resistance showed better bioleaching performance for arsenopyrite. After 18 days of bioleaching, the leaching rate of arsenopyrite reached 100% at a pulp concentration of 0.5%, and after 30 days of bioleaching, the leaching rate of arsenopyrite was 79.96% at a pulp concentration of 1%. Currently, research on arsenopyrite mainly focuses on the control and optimization of environmental conditions, but there have been few studies on the biooxidation process of arsenopyrite at the protein and gene levels. Therefore, combining the results of a one-month bioleaching experiment on arsenopyrite by A. ferriphilus QBS 3 and the analysis of arsenic resistance genes, a bioleaching model of arsenopyrite was constructed, which laid an experimental basis and theoretical foundation for improving the gold recovery rate from refractory arsenic-bearing ores and exploring the arsenic resistance mechanism of microorganisms during the arsenopyrite leaching process.

Nowadays, research on promoting the dissolution of chalcopyrite is important. As a natural symbiotic mineral of chalcopyrite, arsenopyrite will have an impact on the dissolution of chalcopyrite. This paper shows the influence of arsenopyrite on the dissolution of chalcopyrite in an acidic culture medium. The leaching results showed that adding arsenopyrite increased the leaching concentration of copper by 332 mg/L. The residues showed a decrease in sulfur through X-ray diffraction analysis (XRD) and an increase in dissolution degree through scanning electron microscope (SEM). Electrochemical experiments have shown that the rest potential of arsenopyrite is higher than that of chalcopyrite, so there is a galvanic interaction, and the impact on chalcopyrite is greater than that of arsenopyrite. The polarization curve also proves this. Under the interaction of galvanic couples, the reduction of S⁰ production and the enhancement of Cu²⁺ release can promote the dissolution of chalcopyrite. In addition, X-ray photoelectron spectrometer (XPS) analysis under the action of galvanic coupling indicates that more SO₄²⁻ is generated on the surface of chalcopyrite, replacing S_n²⁻/S⁰, and SEM shows a stronger corrosion morphology. All results confirm that the electrochemical effect between arsenopyrite and chalcopyrite promotes the dissolution of chalcopyrite in the acidic culture medium.