Mechanical and corrosion properties of Ti-35Nb-7Zr-xHA composites fabricated by spark plasma sintering

To improve the bioactivity of Ti?Nb?Zr alloy,Ti?35Nb?7Zr?xHA(hydroxyapatite,x=5,10,15and20,mass fraction,%)composites were fabricated by spark plasma sintering.The effects of the HA content on microstructure,mechanical and corrosionproperties of the composites were investigated utilizing X-ray diffraction(XRD),scanning electron microscope(SEM),mechanicaltests and electrochemical tests.Results show that all sintered composites are mainly composed ofβ-Ti matrix,α-Ti andmetal?ceramic phases(CaO,CaTiO3,CaZrO3,TixPy,etc).Besides,some residual hydroxyapatites emerge in the composites(15%and20%HA).The compressive strengths of the composites are over1400MPa and the elastic moduli of composites((5%?15%)HA)present appropriate values(46?52GPa)close to that of human bones.The composite with15%HA exhibits low corrosion currentdensity and passive current density in Hank's solution by electrochemical test,indicating good corrosion properties.Therefore,Ti?35Nb?7Zr?15HA composite might be an alternative material for orthopedic implant applications.

Theoretical investigations on a variable-coefficient generalized forced–perturbed Korteweg–de Vries–Burgers model for a dilated artery,blood vessel or circulatory system with experimental support

Recent theoretical physics efforts have been focused on the probes for nonlinear pulse waves in,for example,variable-radius arteries.With respect to the nonlinear waves in an artery full of blood with certain aneurysm,pulses in a blood vessel,or features in a circulatory system,this paper symbolically computes out an auto-B?cklund transformation via a noncharacteristic movable singular manifold,certain families of the solitonic solutions,as well as a family of the similarity reductions for a variable-coefficient generalized forced–perturbed Korteweg–de Vries–Burgers equation.Aiming,e.g.,at the dynamical radial displacement superimposed on the original static deformation from an arterial wall,our results rely on the axial stretch of the injured artery,blood as an incompressible Newtonian fluid,radius variation along the axial direction or aneurysmal geometry,viscosity of the fluid,thickness of the artery,mass density of the membrane material,mass density of the fluid,strain energy density of the artery,shear modulus,stretch ratio,etc.We also highlight that the shock-wave structures from our solutions agree well with those dusty-plasma-experimentally reported.

Characterizations on Mechanical Properties and In Vitro Bioactivity of Biomedical Ti–Nb–Zr–CPP Composites Fabricated by Spark Plasma Sintering

To alleviate the bio-inert of Ti alloys as hard tissue implants, Ti–35Nb–7Zr–xCPP（calcium pyrophosphate,x = 5, 10, 15, 20 wt%） composites were prepared by mechanical alloying（MA） and following spark plasma sintering（SPS）. Mechanical behaviours and in vitro bioactivity of these composites were investigated systematically. Results showed that the composites consisted of β-Ti matrix, α-Ti, and metal–ceramic phases such as CaO, CaTiO3, CaZrO3, and TixPy. With increasing CPP content, the composites had higher strength（over 1500 MPa） and higher elastic modulus, but suffered almost zero plastic deformation together with lower relative density. When the CPP contents were 5 and 10 wt%,the compressive elastic moduli were 44 and 48 GPa, respectively, which were close to those of natural bones. However, the compressive elastic modulus of the composites increased significantly when CPP contents exceed 10 wt%, thus deteriorating the mechanical compatibility of the composites owing to more α-Ti and metal–ceramic phases. Besides, the surface of Ti–35Nb–7Zr–10CPP composite was deposited as a homogeneous apatite layer during soaking in simulated body fluid（SBF）. It indicates a good bioactivity between the implant materials and living bones.

Bilinear forms through the binary Bell polynomials, N solitons and Backlund transformations of the Boussinesq–Burgers system for the shallow water waves in a lake or near an ocean beach

Water waves are one of the most common phenomena in nature, the studies of which help energy development, marine/offshore engineering, hydraulic engineering, mechanical engineering, etc. Hereby, symbolic computation is performed on the Boussinesq–Burgers system for shallow water waves in a lake or near an ocean beach. For the water-wave horizontal velocity and height of the water surface above the bottom, two sets of the bilinear forms through the binary Bell polynomials and N-soliton solutions are worked out, while two auto-B?cklund transformations are constructed together with the solitonic solutions, where N is a positive integer. Our bilinear forms, N-soliton solutions and B?cklund transformations are different from those in the existing literature. All of our results are dependent on the waterwave dispersive power.