Alloying combined with plastic deformation processing is widely used to improve mechanical properties of pure Zn.As-cast Zn and its alloys are brittle.Beside plastic deformation processing,no effective method has yet ...Alloying combined with plastic deformation processing is widely used to improve mechanical properties of pure Zn.As-cast Zn and its alloys are brittle.Beside plastic deformation processing,no effective method has yet been found to eliminate the brittleness and even endow room temperature super-ductility.Second phase,induced by alloying,not only largely determines the ability of plastic deformation,but also influences strength,corrosion rate and cytotoxicity.Controlling second phase is important for designing biodegradable Zn alloys.In this review,knowledge related to second phases in biodegradable Zn alloys has been analyzed and summarized,including characteristics of binary phase diagrams,volume fraction of second phase in function of atomic percentage of an alloying element,and so on.Controversies about second phases in Zn-Li,Zn-Cu and Zn-Fe systems have been settled down,which benefits future studies.The effects of alloying elements and second phases on microstructure,strength,ductility,corrosion rate and cytotoxicity have been neatly summarized.Mg,Mn,Li,Cu and Ag are recommended as the major alloying elements,owing to their prominent beneficial effects on at least one of the above properties.In future,synergistic effects of these elements should be more thoroughly investigated.For other nutritional elements,such as Fe and Ca,refining second phase is a matter of vital concern.展开更多
Background： The efficacy and safety of telmisartan combined with clopidogrel, leflunomide, or both drugs for immunoglobulin A nephropathy （IgAN） are unclear. This study was designed to evaluate the efficacy and saf...Background： The efficacy and safety of telmisartan combined with clopidogrel, leflunomide, or both drugs for immunoglobulin A nephropathy （IgAN） are unclear. This study was designed to evaluate the efficacy and safety of telmisartan combined with clopidogrel, leflunomide, or both drugs for IgAN. Methods： It is a multicenter, prospective, double-dummy randomized controlled trial. Primary IgAN patients were recruited in 13 renal units across Beijing, China, from July 2010 to June 2012. After a 4-week telmisartan （80 mg/d） wash-in, 400 patients continuing on 80 mg/d telmisartan were randomly assigned to additionally receive placebo （Group A）, 50 mg/d clopidogrel （Group B）, 20 mg/d leflunomide （Group C）, or 50 mg/d clopidogrel and 20 mg/d leflunomide （Group D）. The 24-week intervention was completed by 360 patients. The primary endpoint was change in 24-h proteinuria at 24 weeks. A linear mixed-effect model was used to analyze the changes at 4, 12, and 24 weeks. Generalized estimating equations were used to evaluate changes in hematuria grade. This trial was registered at the Chinese Clinical Trial Registry. Results： The effects oftelmisartan combined with leflunomide on changes in proteinuria （0.36 [95% confidence interval （CI） 0.18 0.55] g/d, P 〈 0.001）, in serum uric acid （76.96 [95% CI 57.44-96.49] μmol/L, P 〈 0.001）, in serum creatinine （9.49 [95% CI 6.54-12.44]μmol/L, P 〈 0.001）, and in estimated glomerular filtration rate （-6.72 [95% CI-9.46 to -3.98] ml.min -1. 1.73 m -2, p 〈 0.001） were statistically significant, whereas they were not statistically significant on changes in systolic and diastolic blood pressure and weight （P 〉 0.05）.Telmisartan combined with clopidogrel had no statistical effect on any outcome, and there was no interaction between the interventions. No obvious adverse reactions were observed. Conclusions： Telmisartan combined with leflunomide, not clopidogrel, is safe and effective for decreasing proteinuria in certain IgAN 展开更多
Fabricated through a newly developed hot-warm rolling process,Zn-0.8 Li(wt%)alloy has ideal strength and ductility far beyond the mechanical benchmark of materials for biodegradable stents.Precipitation of needle-like...Fabricated through a newly developed hot-warm rolling process,Zn-0.8 Li(wt%)alloy has ideal strength and ductility far beyond the mechanical benchmark of materials for biodegradable stents.Precipitation of needle-like Zn in primary p-LiZn4 phase is observed in Zn-Li alloy for the first time.Orientation relationship between them can be described as[1-213]β//[2-1-10](Zn),(10-10)βabout 4.5°from(0002)(Zn).Zn grains with an average size of 640 nm exhibit strong basal texture,detected by transmission electron back-scatter diffraction.Li distribution is determined by three-dimensional atom probe,which reveals the formation of nano-sized metastableα-Li2Zn3 precipitates with a number density of 7.16×10^22 m^-3.The fine lamellar Zn+β-LiZn4 structure,sub-micron grains and the nano-sized precipitates contribute to the superior mechanical properties.展开更多
Zn-Mn-Cu alloys with micro-alloying of Mn and Cu in Zn are developed as potential biodegradable met- als. Although the as-cast alloys are very brittle, their ductilities are significantly improved through hot rolling....Zn-Mn-Cu alloys with micro-alloying of Mn and Cu in Zn are developed as potential biodegradable met- als. Although the as-cast alloys are very brittle, their ductilities are significantly improved through hot rolling. Among the as-cast and the as-hot-rolled alloys, as-hot-rolled Zn-0.35Mn-0.41 Cu alloy has the best comprehensive property. It has yield strength of 198.4 ± 6.7 MPa, tensile strength of 292.4 ± 3.4 MPa, elongation of 29.6 ±3.8% and corrosion rate of 0.050-0.062 mm a^-1. A new ternary phase is characterized and determined to be MnCuZn18, which is embedded in MnZn13, resulting in a coarse cellular/dendritic MnZna3-MnCuZn18 compound structure in Zn-0.75 Mn-0.40Cu alloy. Such a coarse compound structure is detrimental for wrought alloy properties, which guides future design of Zn-Mn-Cu based alloys. The preliminary research indicates that Zn-Mn-Cu alloy system is a promising candidate for potential cardiovascular stent applications.展开更多
基金financially supported by National Key R&D Program of China(2016YFC1102500).
文摘Alloying combined with plastic deformation processing is widely used to improve mechanical properties of pure Zn.As-cast Zn and its alloys are brittle.Beside plastic deformation processing,no effective method has yet been found to eliminate the brittleness and even endow room temperature super-ductility.Second phase,induced by alloying,not only largely determines the ability of plastic deformation,but also influences strength,corrosion rate and cytotoxicity.Controlling second phase is important for designing biodegradable Zn alloys.In this review,knowledge related to second phases in biodegradable Zn alloys has been analyzed and summarized,including characteristics of binary phase diagrams,volume fraction of second phase in function of atomic percentage of an alloying element,and so on.Controversies about second phases in Zn-Li,Zn-Cu and Zn-Fe systems have been settled down,which benefits future studies.The effects of alloying elements and second phases on microstructure,strength,ductility,corrosion rate and cytotoxicity have been neatly summarized.Mg,Mn,Li,Cu and Ag are recommended as the major alloying elements,owing to their prominent beneficial effects on at least one of the above properties.In future,synergistic effects of these elements should be more thoroughly investigated.For other nutritional elements,such as Fe and Ca,refining second phase is a matter of vital concern.
文摘Background： The efficacy and safety of telmisartan combined with clopidogrel, leflunomide, or both drugs for immunoglobulin A nephropathy （IgAN） are unclear. This study was designed to evaluate the efficacy and safety of telmisartan combined with clopidogrel, leflunomide, or both drugs for IgAN. Methods： It is a multicenter, prospective, double-dummy randomized controlled trial. Primary IgAN patients were recruited in 13 renal units across Beijing, China, from July 2010 to June 2012. After a 4-week telmisartan （80 mg/d） wash-in, 400 patients continuing on 80 mg/d telmisartan were randomly assigned to additionally receive placebo （Group A）, 50 mg/d clopidogrel （Group B）, 20 mg/d leflunomide （Group C）, or 50 mg/d clopidogrel and 20 mg/d leflunomide （Group D）. The 24-week intervention was completed by 360 patients. The primary endpoint was change in 24-h proteinuria at 24 weeks. A linear mixed-effect model was used to analyze the changes at 4, 12, and 24 weeks. Generalized estimating equations were used to evaluate changes in hematuria grade. This trial was registered at the Chinese Clinical Trial Registry. Results： The effects oftelmisartan combined with leflunomide on changes in proteinuria （0.36 [95% confidence interval （CI） 0.18 0.55] g/d, P 〈 0.001）, in serum uric acid （76.96 [95% CI 57.44-96.49] μmol/L, P 〈 0.001）, in serum creatinine （9.49 [95% CI 6.54-12.44]μmol/L, P 〈 0.001）, and in estimated glomerular filtration rate （-6.72 [95% CI-9.46 to -3.98] ml.min -1. 1.73 m -2, p 〈 0.001） were statistically significant, whereas they were not statistically significant on changes in systolic and diastolic blood pressure and weight （P 〉 0.05）.Telmisartan combined with clopidogrel had no statistical effect on any outcome, and there was no interaction between the interventions. No obvious adverse reactions were observed. Conclusions： Telmisartan combined with leflunomide, not clopidogrel, is safe and effective for decreasing proteinuria in certain IgAN
基金supported financially by the National Key R&D Program of China (No.2016YFC1102500)the National Natural Science Foundation of China (No.51871020)
文摘Fabricated through a newly developed hot-warm rolling process,Zn-0.8 Li(wt%)alloy has ideal strength and ductility far beyond the mechanical benchmark of materials for biodegradable stents.Precipitation of needle-like Zn in primary p-LiZn4 phase is observed in Zn-Li alloy for the first time.Orientation relationship between them can be described as[1-213]β//[2-1-10](Zn),(10-10)βabout 4.5°from(0002)(Zn).Zn grains with an average size of 640 nm exhibit strong basal texture,detected by transmission electron back-scatter diffraction.Li distribution is determined by three-dimensional atom probe,which reveals the formation of nano-sized metastableα-Li2Zn3 precipitates with a number density of 7.16×10^22 m^-3.The fine lamellar Zn+β-LiZn4 structure,sub-micron grains and the nano-sized precipitates contribute to the superior mechanical properties.
基金supported financially by the National Key R&D Program of China(No.2016YFC1102500)
文摘Zn-Mn-Cu alloys with micro-alloying of Mn and Cu in Zn are developed as potential biodegradable met- als. Although the as-cast alloys are very brittle, their ductilities are significantly improved through hot rolling. Among the as-cast and the as-hot-rolled alloys, as-hot-rolled Zn-0.35Mn-0.41 Cu alloy has the best comprehensive property. It has yield strength of 198.4 ± 6.7 MPa, tensile strength of 292.4 ± 3.4 MPa, elongation of 29.6 ±3.8% and corrosion rate of 0.050-0.062 mm a^-1. A new ternary phase is characterized and determined to be MnCuZn18, which is embedded in MnZn13, resulting in a coarse cellular/dendritic MnZna3-MnCuZn18 compound structure in Zn-0.75 Mn-0.40Cu alloy. Such a coarse compound structure is detrimental for wrought alloy properties, which guides future design of Zn-Mn-Cu based alloys. The preliminary research indicates that Zn-Mn-Cu alloy system is a promising candidate for potential cardiovascular stent applications.
