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This study numerically investigates the effects of damping ratios on flow-induced vibration (FIV) of two-degree-of-freedom elastically mounted tandem cylinders. By setting the tandem spacing between cylinder centers to four cylinder diameters, the FIV problem was solved using the two-dimensional unsteady Reynolds-averaged Navier–Stokes equations and the shear stress transport k − ω turbulence model. Four typical damping ratios of 0.0036, 0.036, 0.198, and 0.36 are employed to explore the effects of damping ratios on the FIV response. Simulation results show that the peak transverse amplitudes and the fluid force coefficients of cylinders generally decrease with increasing damping ratios. Owing to the presence of lock-in region in the streamwise vibration of the downstream cylinder for ζ = 0.36 , its streamwise vibration amplitude is larger than those for the damping ratio ζ = 0.198 when the reduced velocity U r ≥ 8. With the increase in damping ratios, trajectories of the downstream cylinder become more regular. It is found that the damping ratio has little impact on the frequency capture phenomenon in the cross-flow direction, while the frequency capture phenomenon is first discovered in the in-line direction, which depends on the damping ratio. A transition in the vortex shedding mode is observed as the damping ratio increases. The increase in damping ratio contributes to the stabilization of energy transfer. It is suggested that damping ratios play a significant role in the FIV responses of tandem cylinders. [ABSTRACT FROM AUTHOR]

A major driver of global climate change is the rising concentration of atmospheric CO 2 , the mitigation of which requires the development of efficient and sustainable carbon capture technologies. Solid porous adsorbents have emerged as promising alternatives to liquid amine counterparts due to their potential to reduce regeneration costs. Among them, porous carbons stand out for their high surface area, tailorable pore structure, and exceptional thermal and mechanical properties, making them highly robust and efficient in cycling operations. Moreover, porous carbons can be synthesized from readily available organic (waste) streams, reducing costs and promoting circularity. Lignin, a renewable and abundant by-product of the forest products industry and emerging biorefineries, is a complex organic polymer with a high carbon content, making it a suitable precursor for carbon-based adsorbents. This review explores lignin's sources, structure, and thermal properties, as well as traditional and emerging methods for producing lignin-based porous adsorbents. We examine the physicochemical properties, CO 2 adsorption mechanisms, and performance of lignin-derived materials. Additionally, the review highlights recent advances in lignin valorization and provides critical insights into optimizing the design of lignin-based adsorbents to enhance CO 2 capture efficiency. Finally, it addresses the prospects and challenges in the field, emphasizing the significant role that lignin-derived materials could play in advancing sustainable carbon capture technologies and mitigating climate change.

The study aimed to investigate if a construct of porous improved biphasic calcium phosphate (BCP) combined with osteogenically induced periodontal ligament stem cells (PDLSCs) could repair periodontal defect. Human PDLSCs were cultured, identified, and osteogenically induced, and then seeded on the improved BCP, assessed by scanning electron microscopy and MTT method. Afterwards, PDLSC-seeded scaffolds were used in six Beagle dogs' alveolar bone dehiscence model, and new bone formation was assessed by three-dimensional micro-computed tomographic imaging, fluorescence, and light microscopy at 4 th , 8 th and 12 th week postoperatively. Results showed that PDLSCs were positive for STRO-1 and vimention, while negative for cytokeratin. They had the capacity to undergo osteogenic differentiation in vitro . When seeded on the improved BCP, PDLSCs exhibited significantly great viability. The use of PDLSC-seeded improved BCP promoted effective periodontal regeneration. In conclusion, this study demonstrates the potential of improved BCP combined with PDLSCs as a promising method for periodontal regeneration., Competing Interests: None.