The two main causes of implant surgery failure are aseptic loosening and bacterial-induced implant-associated infections. To make bone defect implants effective for a long time, the ideal scaffold should take into account the two functions of osseointegration and anti-infection. Therefore, on the basis of the low-elastic-modulus Ti-10Ta-2Nb-2Zr (TTNZ) alloys developed by the research group in the early stage, this study intends to combine the vancomycin-loaded hydrogel with the 3D-printed through-hole porous titanium alloy scaffold to endow 3D-printed TTNZ scaffolds with antibac-terial properties. The local release rate of vancomycin and the effect of this composite system on osseointegration from the aspects of cell adhesion, cell proliferation, osteogenesis-related gene expression, and the antibacterial properties were investigated by the inhibition zone test and the adhesion/free antibacterial test. The results showed that loading 2.5 wt.% and 5 wt.% vancomycin did not affect the structure of chitosan–hyaluronic acid hydrogel. The properties of the hydrogels were examined by scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR), and vancomycin release experiments in vitro. When combined with porous scaffolds, the drug-loaded hydrogels exhibited slower drug release rates and longer release times. In addition, in vitro studies found that the TTNZ scaffolds loaded with 5 wt.% vancomycin had a certain effect on the expression of osteogenesis-related genes in cells, but the antibacterial effect was the best. The porous scaffolds loaded with 2.5 wt.% vancomycin hydrogel TTNZ scaffolds did not inhibit cell proliferation, adhesion, alkaline phosphatase activity, and osteogenesis-related gene expression, but the antibacterial effect on free bacteria was not as good as that of TTNZ scaffolds loaded with 5 wt.% vancomycin. This study, complementing the advantages of the two and controlling the local release rate of vancomycin, provides a new idea for future 3D printing of titanium alloy stents for anti-infection.

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Gas pulsations excited by reciprocating compressors could introduce severe vibrations and noise in piping systems. When pulsating gas flows through the reducers, the changes in flow characteristics, such as velocity and damping coefficient, will affect the pressure pulsations. To circumvent these constraints, a two-tank element is introduced to control the gas pulsation that is still strong in the piping system with a surge tank. Installing another surge tank to form a two-tank element is more flexible and costs lower than replacing the original surge tank with a larger one. In this work, a theoretical model based on the wave theory was proposed to study the transferring mechanism of gas pulsations in the pipeline with the two-tank element. By considering the damping coefficient and the Mach number, the distributions of the pressure pulsations were predicted by the theoretical model and agreed with the three-dimensional fluid dynamics transient analysis. Three experiments were conducted to prove that the suppression capability of the two-tank element is as good as that of a single-tank element (surge tank) with the same surge volume. The volume optimization of the twotank element is implemented by selecting the best allocations of the two tanks' volumes to achieve larger reductions of pressure pulsations. Assuming that the total surge volume is constant, we found that the smaller the volume of the front tank (near the cylinder) is, the lower the pulsation levels are. The optimized result proves that in some conditions the two-tank element could control pulsations better than the single-tank element with the same surge volume.

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