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A laser-induced periodic surface structure (LIPSS) was shown to have antibacterial adhesion properties in previous research. In this study, the antibacterial performance of LIPSS on traditional biometals (stainless steel and titanium alloy) and a potential biometal (zirconium-based bulk metallic glass, Zr-BMG) was investigated. A femtosecond laser was used to fabricate LIPSS on the specimens. Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) were used to examine the antibacterial behavior of the LIPSS samples. The bacterial adhesion force on each specimen was evaluated by an atomic force microscopy (AFM) cell probe. The results showed that the LIPSS on all three metal surfaces significantly lowered antibacterial adhesion compared to polished metal specimens. E. coli demonstrated a higher adhesion force but a lower surface adhesion rate compared to S. aureus. The Zr-BMG specimen with LIPSS has multiple antimicrobial mechanisms (physical antiadhesion and chemical elimination), while the traditional biometals (316L and TC4) mainly offer physical antiadhesion. Finally, an in vitro/vivo study showed that specimens with LIPSS surfaces did not significantly affect the biocompatibility of the specimens. This study reveals that the Zr-BMG specimen with femtosecond laser-processed LIPSS is an ideal choice for achieving an antibacterial surface.

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ReB 2 -type hexagonal Osmium diboride (OsB 2 ) has been predicted to exhibit higher hardness than its orthorhombic phase, but hexagonal-orthorhombic phase transformation occurs at temperature higher than 600°C, resulting in the decrease in its hardness. Therefore, ReB 2 -type hexagonal OsB 2 samples with Re addition were produced by a combination of mechanochemical method and pressureless sintering technique, and the effects of Rhenium (Re) addition on phase composition, thermal stability and mechanical properties of OsB 2 were investigated in this study. X-ray diffraction (XRD) analysis of the as-synthesized powders by high-energy ball milling indicates the formation of hexagonal Os 1-x Re x B 2 solid solution with Re concentration of 5 and 10 at.% without forming a second phase. After being sintered at 1700°C, part of the hexagonal phase in OsB 2 transformed to orthorhombic structure, while Os 0.95 Re 0.05 B 2 and Os 0.9 Re 0.1 B 2 maintained their hexagonal structure. This suggests that the thermal stability of the hexagonal OsB 2 was significantly improved with the addition of Re. Scanning electron microscopy (SEM) photographs show that all of the as-sintered samples exhibit a homogeneous microstructure with some pores and cracks formed throughout the samples with the relative density >90%. The measurements of micro-hardness, nano-hardness, and Young's modulus of the OsB 2 increased with Re addition, and these properties of the sample with 5 at.% addition of Re is higher than that with 10 at.% Re. K E Y W O R D Shardness, Os 1-x Re x B 2 , phase composition, thermal stability | INTRODUCTIONSuper-hard materials, due to their high hardness, high bulk modulus and high wear resistance, are widely used in machining, construction, aerospace, processing of new materials, automobile, and other fields.1 Conventional super-hard materials, e.g., diamond and c-BN, have been considered as the best option for fulfilling industrial machining requirements. 2-4 However, diamond cannot effectively machine steel or other ferrous metals due to the tendency to form iron carbide at elevated temperatures. c-BN would cut these ferrous materials, but it must be synthesized under high-pressure and high-temperature conditions, which makes it very expensive. To overcoming these shortcomings, it is highly desirable to develop new class of super-hard materials. 5During the past decade, efforts have been devoted to design and synthesis new super-hard materials for both scientific and practical application purposes. Recent searches on new super-hard materials mainly focus on two classes