Evolution of microstructural and mechanical properties of AISI 316 during continuous drive friction welding process

The aim of present study is introducing a method by subdividing friction welding phases into three steps according to the temperature change during continuous drive friction welding operation. Thermal curve allowable subdividing of the friction welding phase's time into three distinct periods, while the microstructure evolution during friction welding goes through three different situations. The effects of three distinct periods were achieved by macro-microscopy, microhardness HV_(0.1), tensile tests and scanning electronic microscopy(SEM).The results clearly show that the microstructure during the friction phase goes through three completely different situations which mechanically influenced on microstructure, tensile strength and ductility of the welded joint.

In vitro and in vivo proves of concept for the use of a chemically cross-linked poly(ester-urethaneurea)scaffold as an easy handling elastomeric biomaterial for bone regeneration

Bone loss can occur as a result of various pathologies,traumas and injuries and poor bone healing leads to functionally debilitating condition,loss of self-sufficiency and deterioration in life quality.Given the increasing incidence of facial trauma and the emergence of new procedural techniques,advanced scaffolds are currently developed as substitutes for bone tissue engineering.In this study,we investigated the capability of a chemically cross-linked e-caprolactone-based poly(esterurethane-urea)(PCLU)scaffold to support bone regeneration.In vitro assays demonstrated that PCLU scaffolds could be colonized by cells through direct cell seeding and cell migration from outside to scaffold inside.Moreover,PCLU scaffolds could provide a suitable environment for stem cells proliferation in a 3D spatial arrangement,and allowed osteogenic differentiation under appropriate induction.In vivo results revealed the osteogenic properties of PCLU scaffolds through a drilled-hole femoral bone defect repair improvement in rats.Using histology and microtomography analysis,we showed that PCLU scaffolds fit well the bone cavity and were eventually entrapped between the newly formed trabeculae.Finally,no sign of inflammation or rejection was noticed.We envision that PCLU scaffolds can provide the clinicians with a substitute having appropriate characteristics for the treatment of bone defects.