Simulation of Friction Stir Welding of AZ31 Mg Alloys.

Friction stir welding has been extensively applied for the high-quality bonding of Mg alloys. The welding temperature caused by friction and plastic deformation is essential for determining the joint characteristics, especially the residual stress and weld microstructure. In this work, a modified moving heat source model was proposed by considering the variations in heat generation caused by friction shear stress at both the side and bottom surfaces of the tool.

Finite-element analysis of different fixation types after Enneking II + III pelvic tumor resection.

The current primary treatment approach for malignant pelvic tumors involves hemipelvic prosthesis reconstruction following tumor resection. In cases of Enneking type II + III pelvic tumors, the prosthesis necessitates fixation to the remaining iliac bone. Prevailing methods for prosthesis fixation include the saddle prosthesis, ice cream prosthesis, modular hemipelvic prosthesis, and personalized prosthetics using three-dimensional printing.

Ant-Inspired Bionic Design Method for the Support Structure of the Fengyun-3 Satellite Payload Infilled with Lattice Structure.

Owing to their high design freedom and excellent performance, lattice structures have shown outstanding capabilities and great potential in aeronautics and astronautics fields. In this paper, we propose a method to construct lattice structures by parameterizing biological features. An ant-leg configuration is used as the bionic object to generate a bionic lightweight design with a gradient lattice structure.

Study on the Mechanical Properties of Bionic Protection and Self-Recovery Structures.

A novel protective structure, based on shrimp chela structure and the shape of odontodactylus scyllarus, has been shown to improve impact resistance and energy absorption. A finite element model of NiTi alloy with shape memory was constructed based on the basic principles of structural bionics. The protective structure utilizes NiTi alloy as the matrix, a material with many advantages including excellent compression energy absorption, reusability after unloading, and long life.

Regulating Precipitates by Simple Cold Deformations to Strengthen Mg Alloys: A Review.

Regulating precipitates is still an important issue in the development of high-strength Mg alloys, due to it determining the precipitation hardening effect. Cold deformation, as a simple and low-cost method, can remarkably influence the precipitate features. It is found that pre-cold deformation before aging can be utilized to enhance the precipitation hardening effect of Mg alloys.

Improving Tensile and Compressive Properties of an Extruded AZ91 Rod by the Combined Use of Torsion Deformation and Aging Treatment.

In this study, AZ91 magnesium alloy rods were used to investigate the effects of torsion deformation on microstructure and subsequent aging behavior. Extruded AZ91 rod has a uniform microstructure and typical fiber texture. Torsion deformation can generate a gradient microstructure on the cross-section of the rod.

Comparative study on twinning characteristics during two post-weld compression paths and their effects on joint enhancement.

Friction stir welding (FSW) has promising application potential in Mg alloys. However, the texture distribution in stir zone (SZ) is usually complicated for Mg alloys, which deterioriates the joint performance. In this study, the texture distribution in SZ was tailored by applying two kinds of post-weld compression deformation along normal direction (ND) or welding direction (WD) of the FSWed AZ31 Mg alloy plates.

The different effects of twin boundary and grain boundary on reducing tension-compression yield asymmetry of Mg alloys.

In the present study, a coarse grained AZ31 plate was refined by twin boundaries (TBs) and grain boundaries (GBs), respectively. A comparative study about the different effects of grain refinements by GBs and by TBs on tension-compression yield asymmetry was performed. Our results show that both the refinements by GBs and by TBs increase the tensile and compressive yield strengths, but to a different degree.

Surface functionalized mesoporous silica nanoparticles with natural proteins for reduced immunotoxicity.

Mesoporous silica nanoparticles (MSNs) present themselves as one of the most promising nano-carriers for drug delivery. To reduce their immunotoxicities, in this study, natural proteins of gelatin (Gel), bovine serum albumin (BSA), and lysozyme (Lys) were employed as end-caps of MSNs by using succinic anhydride as an intermediate linker, thus leading to fabrication of MSNs/protein nanocomposites, respectively. Furthermore, combined techniques of SEM, TEM, FTIR, and zeta potential instruments were utilized to monitor the construction processes of MSNs/protein nanocomposites, respectively.

Surface engineering of titanium with potassium hydroxide and its effects on the growth behavior of mesenchymal stem cells.

To improve the corrosion resistance and biological performance of commercially pure titanium (cp-Ti) substrates, potassium hydroxide was employed to modify the surfaces of titanium substrates, followed by biomimetic deposition of apatite on the substrates in a simulated body fluid. The morphologies of native and treated titanium substrates were characterized by field emission scanning electron microscopy (FE-SEM). Treatment with potassium hydroxide led to the formation of intermediate layers of potassium titanate on the surfaces of titanium substrates, while apatite was subsequently deposited onto the intermediate layer.

Characterization and structural analysis of zinc-substituted hydroxyapatites.

The substitution of Zn in hydroxyapatite (HA) crystals was examined via comprehensive characterization techniques. Nanosized HA crystals were synthesized by the wet chemical method in aqueous solutions including various amounts of Zn ions. X-ray fluorescent spectroscopy was used to examine the amount of Zn in the HA precipitates.

Effects of porosity and crystallinity of glass ceramics on the in vivo bioactive response.

Two types of glass ceramics with different porosities and crystallinities were produced by sintering 45S5 Bioglass particulates. The in vivo bioactive response of the glass ceramics was evaluated by implanting them in rabbit muscle sites. After six weeks implantation, silicon-rich networks were observed on both types of ceramics, but the number of networks was much larger in the poorly crystallized dense ceramics than in the well crystallized porous ones.

Chemical stability of ZnO nanostructures in simulated physiological environments and its application in determining polar directions.

The in vitro chemical stability and etching of ZnO nanostructures in simulated physiological solution (SPS) were studied using electron microscopy. Calcium hydrogen phosphate thin layers were observed to be uniformly deposited on the surfaces of ZnO nanomaterials in SPS. Electron diffraction and high-resolution transmission electron microscopy revealed that the calcium hydrogen phosphate layers were amorphous and had excellent interfacial contact with the nanocrystals.

Bioactive films on metallic surfaces for osteoconduction.

A fast and effective electrochemical method was developed to make a dense calcium phosphate films on titanium and stainless steel for hard tissue replacement. The surfaces of titanium and stainless steel were cathodically treated in an electrochemical cell. By controlling the treatment parameters, a film of 100-nm thickness was deposited on the metal surface in several minutes.

A comparative study of calcium phosphate formation on bioceramics in vitro and in vivo.

Formation of calcium phosphate (Ca-P) on various bioceramic surfaces in simulated body fluid (SBF) and in rabbit muscle sites was investigated. The bioceramics were sintered porous solids, including bioglass, glass-ceramics, hydroxyapatite, alpha-tricalcium phosphate and beta-tricalcium phosphate. The ability of inducing Ca-P formation was compared among the bioceramics.

A comparative study of electrochemical deposition and biomimetic deposition of calcium phosphate on porous titanium.

Coating porous titanium with calcium phosphate (Ca-P) is an effective way to enhance titanium's osteoinduction capability. This study investigated the effectiveness of two coating methods: biomimetic deposition (BD) and electrochemical deposition (ED) in aqueous solutions. The titanium surfaces were treated by acidic etching and alkaline before coating.