Ultrashort pulsed (USP) laser machining is a promising approach for processing binderless nanopolycrystalline diamond (NPD), which combines isotropic ultra-high hardness and high thermal stability. This study systematically investigates USP laser ablation to identify suitable conditions for advanced microtool fabrication. The influence of pulse duration ( τ ), wavelength ( λ ), fluence ( F ), pulse frequency ( f ) and pulse and track overlaps ( O x , O y ) on orthogonal and quasi-tangential ablation of NPD was evaluated. The single-pulse ablation threshold ranged from 1.56 J / cm 2 for green fs irradiation to 8.82 J / cm 2 for IR ns irradiation. In orthogonal ablation, increasing f improved ablation efficiency under high-fluence conditions, with IR fs giving the highest material removal, while green fs at low frequency provided the best compromise between low roughness and high efficiency. In the overlap study, O x = 0.6 and O y = 0.8 yielded the lowest surface roughness. For quasi-tangential machining, an optimum parameter window was identified with R a = 13 nm and S a = 51 nm . Finally, NPD micro milling tools with sharp cutting edges ( r ϵ = 1.03 ± 0.13 μ m ) and low surface roughness were successfully fabricated. • Binderless nanopolycrystalline diamond showed the lowest ablation threshold under green femtosecond laser irradiation and the highest threshold under infrared nanosecond irradiation. • In orthogonal machining, green femtosecond irradiation at low frequency provided the best balance between smooth surfaces and efficient material removal, while infrared femtosecond irradiation at high frequency produced the highest removal rates. • A narrow optimum process window was identified for quasi-tangential machining, yielding very low surface roughness and high surface quality on cylindrical binderless nanopolycrystalline diamond. • Micro milling tools were successfully fabricated by combining orthogonal ablation for flute generation with quasi-tangential ablation for tool shaping, producing sharp cutting edges and low surface roughness in binderless nanopolycrystalline diamond.

• Microstructure formation during sputtering of FePt-C films was numerically modeled. • The factors influencing microstructure formation were investigated. • Elastic strain is essential for the formation of island-like microstructure. • Segregant enhances vertical growth of FePt grain by shifting atom supply position. • Sputtering rate influences the size and the risk of coalescence of FePt grains. This study investigates microstructure formation in FePt-C nanogranular films deposited on MgO substrates during sputtering using the phase-field method, aiming to identify the key factors promoting the creation of an island-like microstructure, which is essential for the high recording density required in hard disk drives. Simulations reproduced the growth and coarsening of FePt grains, indicating that elastic-strain energy relaxation contributes significantly toward the formation of well-isolated FePt islands. The addition of C as a segregant shifts the position of the atoms supplied by sputtering closer to the top surface of the FePt grains, promoting their vertical growth. Furthermore, the film microstructure varies with the sputtering rate: lower rates result in coarser structures, whereas higher rates result in finer structures, albeit at the risk of grain coalescence. The results of this study suggest that the final microstructure is determined by the interplay of energetic and kinetic factors, specifically the interfacial and elastic strain energies and the diffusion and sputtering rates. These findings will enable the formulation of fabrication strategies for optimal high-performance FePt magnetic recording films.

Diabetic patients often face poor repair of bone defects, which may be related to the reduced osteogenic capacity of bone marrow mesenchymal stem cells (BMSCs) and the polarization of M1/M2 macrophage imbalance leading to an inflammatory response. The ability of BMSC-derived exosomes (BMSC-Exos) and BMP2 to exert both bone tissue regeneration and immunomodulation is expected to resolve this clinical dilemma. In this study, we demonstrate that exosomes derived from BMP2-treated BMSCs (BMP2-Exos) in a diabetic microenvironment exhibit enhanced osteogenic effects. Additionally, compared to the blank control group, macrophages stimulated by BMP2-Exos were more polarized towards the M2 type. These results were verified in vivo by GelMA loaded exosomes in the diabetic rat skull defect model. Importantly, we found that BMP2-Exos can upregulate the PI3K/AKT signaling pathway in diabetic BMSCs and improved osteogenic function and M2 macrophage polarization in diabetes-impaired BMSC-Exos in vitro. In conclusion, the present study revealed that BMP2 pretreatment can enhance the ability of BMSC-Exos to promote osteogenesis in diabetic bone defect areas, provides a preliminary exploration of the underlying mechanisms. Our study provided important experimental basis and innovative ideas for the application of exosomes therapy in the field of bone tissue regeneration.