Rotary swaging(RS)of alloy Mg-1.03Zn-0.66Ca(ZX11)was shown to refine the average grain size to 4.5±1.2μm in a longitudinal section and 4.8±0.9μm in a transverse section.In addition,a small amount of Mg2Ca ...Rotary swaging(RS)of alloy Mg-1.03Zn-0.66Ca(ZX11)was shown to refine the average grain size to 4.5±1.2μm in a longitudinal section and 4.8±0.9μm in a transverse section.In addition,a small amount of Mg2Ca particles about 300nm in size and Mg6Zn3Ca2 particles with a size of about lOOnm was detected.This resulted in pronounced strengthening:the yield strength and the ultimate tensile strength rose to 210±8 MPa and 276±6 MPa,respectively,while the elongation hardly decreased(22.0±1.8% and 18.3±2.9% before and after RS).Furthermore,RS led to an increase in the fatigue limit of the alloy from 120 MPa to 135 MPa and did not impair its resistance to chemical corrosion.The studies in vitro showed that ZX11 induces hemolysis without inhibiting the viability of peripheral blood mononuclear cells and has a more pronounced cytotoxic effect on tumor cells in comparison with non-transformed cells.No significant difference of the latter effect between the initial and the deformed states was observed.展开更多
In the present work, Polyhydroxybutyrate （PHB）/Hydroxyapatite （HA） porous composites （10%, 20%, 30 %, 40%, 50% weight HA） were obtained by sintering. PHB/20% HA optimally combines satisfactory mechanical propert...In the present work, Polyhydroxybutyrate （PHB）/Hydroxyapatite （HA） porous composites （10%, 20%, 30 %, 40%, 50% weight HA） were obtained by sintering. PHB/20% HA optimally combines satisfactory mechanical properties with a high content of the bioactive component （HA）. Porous PHB/20% HA scaffolds have shown high mechanical properties （compressive strength of 106 MPa and Young＇s modulus of 901 MPa）. A high volume fraction of interconnected pores （〉 50 vol.%） was achieved with pore size of 50 grn - 500 gm. Biocompatibility of porous pure PHB and PHB/20%HA, as its osseointegration were assessed in vitro and after implantation in laboratory animals. PHB/20% HA （-5% ＋ 0.9%） and pure PHB ~3% ~ 1.4%） samples after 24 hours of incubation with human leucocytes showed no significant level of cytotoxicity when p = 0.648 （p-value）. In vitro massive adhesion of mouse Multipotent Mesenchymal Stromal Cells （MMSC） to the surface of both porous samples was shown. PHB/20% HA induced more intensive MMSC proliferation compared to pure PHB, which are 31% ＋ 6.1% and 20% ＋ 5.7 % respectively when p = 0.039. We observed the resorption （implant surface area was reduced by 49 %） and integration of the porous PHB/20% HA samples into surrounding tissues after 30 days of implantation. The signs of osteoclasts accumulation, neo-angigenesis and new bone formation were observed, which make PHB/20% HA promising for bone tissue engineering.展开更多
基金Funding support of investigations of microstructure,mechanical properties,corrosion resistance,biocompatibility and cytotoxicity was provided by the Russian Science Foundation(project#18-45-06010)Part of this work relating to studies of fatigue behavior was carried out within the governmental task#075-00947-20-00.
文摘Rotary swaging(RS)of alloy Mg-1.03Zn-0.66Ca(ZX11)was shown to refine the average grain size to 4.5±1.2μm in a longitudinal section and 4.8±0.9μm in a transverse section.In addition,a small amount of Mg2Ca particles about 300nm in size and Mg6Zn3Ca2 particles with a size of about lOOnm was detected.This resulted in pronounced strengthening:the yield strength and the ultimate tensile strength rose to 210±8 MPa and 276±6 MPa,respectively,while the elongation hardly decreased(22.0±1.8% and 18.3±2.9% before and after RS).Furthermore,RS led to an increase in the fatigue limit of the alloy from 120 MPa to 135 MPa and did not impair its resistance to chemical corrosion.The studies in vitro showed that ZX11 induces hemolysis without inhibiting the viability of peripheral blood mononuclear cells and has a more pronounced cytotoxic effect on tumor cells in comparison with non-transformed cells.No significant difference of the latter effect between the initial and the deformed states was observed.
文摘In the present work, Polyhydroxybutyrate （PHB）/Hydroxyapatite （HA） porous composites （10%, 20%, 30 %, 40%, 50% weight HA） were obtained by sintering. PHB/20% HA optimally combines satisfactory mechanical properties with a high content of the bioactive component （HA）. Porous PHB/20% HA scaffolds have shown high mechanical properties （compressive strength of 106 MPa and Young＇s modulus of 901 MPa）. A high volume fraction of interconnected pores （〉 50 vol.%） was achieved with pore size of 50 grn - 500 gm. Biocompatibility of porous pure PHB and PHB/20%HA, as its osseointegration were assessed in vitro and after implantation in laboratory animals. PHB/20% HA （-5% ＋ 0.9%） and pure PHB ~3% ~ 1.4%） samples after 24 hours of incubation with human leucocytes showed no significant level of cytotoxicity when p = 0.648 （p-value）. In vitro massive adhesion of mouse Multipotent Mesenchymal Stromal Cells （MMSC） to the surface of both porous samples was shown. PHB/20% HA induced more intensive MMSC proliferation compared to pure PHB, which are 31% ＋ 6.1% and 20% ＋ 5.7 % respectively when p = 0.039. We observed the resorption （implant surface area was reduced by 49 %） and integration of the porous PHB/20% HA samples into surrounding tissues after 30 days of implantation. The signs of osteoclasts accumulation, neo-angigenesis and new bone formation were observed, which make PHB/20% HA promising for bone tissue engineering.
