Dressings are commonly used to treat skin wounds. In this study, we aimed to develop a new scaffold composed of a polyvinyl alcohol (PVA) hydrogel containing granule-lyophilised platelet-rich fibrin (G-L-PRF) as a dressing. G-L-PRF was prepared by freeze-drying and was then incorporated into PVA hydrogel by freezing-thawing. Notably, the mechanical strength and degradation rate of the scaffold were found to be related to G-L-PRF concentrations, reaching 6.451 × 10−2 MPa and 17–22%, respectively, at a concentration of 1%. However, the strength decreased and the degradation was accelerated when the G-L-PRF concentration was over 1%. The elastic properties and biocompatibility of the scaffold were independent of G-L-PRF concentration, and both showed excellent elasticity and biocompatibility. The release of vascular endothelial growth factor and platelet-derived growth factor-AB was no significant time dependent. Additionally, application of 1% G-L-PRF/PVA to acute full-thickness dorsal skin wounds accelerated wound closure at days 7 and 9. Healing also increased on day 11. Histological and immunohistochemical analyses showed that the scaffold enhanced granulation tissue, maturity, collagen deposition, and new vessel formation. These results demonstrated that the prepared G-L-PRF/PVA scaffolds accelerated wound healing in acute full-thickness skin wounds, suggesting potential applications as an ideal wound dressing.

Current field unbalance estimation methods regards “flexible rotors with lumped mass” as the main research object, and most of them need a stop running to take trial weights. Due to its test speed closing to the critical speed, the process of balance is really complicated and dangerous. This paper concerns rotors which unbalance state shows a continuous spatial distribution. Firstly, a dynamic finite element (FE) model of the rotor system is built, the inherent relations and differences between the dynamics transfer matrix and influence coefficient (IC) matrix are analyzed, and then, an extended dynamics matrix with arbitrary dimension is obtained based on the principle of IC balancing method. Secondly, the continuous distribution mass eccentricity curve is represented as mass eccentricity point on each FE model node, and the unbalance forces imposing on each FE model node are identified by the extended dynamics matrix. Finally, the theoretic analysis and experiment is presented to verify this method, and the result shows that unbalance forces on all FE model nodes can be identified accurately with less measuring points, and higher order modal components of the distributed unbalance are balanced effectively.