The main factors limiting the mass production of TiAl-based components are the high reactivity of TiAl-based alloys with the crucible or mould at high temperature.In this work,various crucibles (e.g.CaO,Y2O3 ceramic c...The main factors limiting the mass production of TiAl-based components are the high reactivity of TiAl-based alloys with the crucible or mould at high temperature.In this work,various crucibles (e.g.CaO,Y2O3 ceramic crucibles and water-cooled copper crucible) were used to fabricate the Ti-47Al-2Cr-2Nb alloy in a vacuum induction furnace.The effects of crucible materials and melting parameters on the microstructure and mechanical properties of the alloy were analyzed by means of microstructure observation,chemical analysis,tensile test and fracture surface observation.The possibilities of melting TiAl alloys in crucibles made of CaO and Y2O3 refractory materials were also discussed.展开更多
目的通过研究膀胱鳞状细胞癌(BSCC)患者的预后独立危险因素,建立可个体化预测BSCC患者生存预后的Nomogram模型。方法收集SEER Research Plus数据库中2000年至2018年诊断为BSCC的1879例患者的临床资料,采用COX回归分析影响BSCC患者预后...目的通过研究膀胱鳞状细胞癌(BSCC)患者的预后独立危险因素,建立可个体化预测BSCC患者生存预后的Nomogram模型。方法收集SEER Research Plus数据库中2000年至2018年诊断为BSCC的1879例患者的临床资料,采用COX回归分析影响BSCC患者预后的独立危险因素,将COX多因素分析所得到的独立危险因素构建成Nomogram模型,采用一致性指数(C-index)和绘制Calibration校准曲线来验证Nomogram模型准确性。结果BSCC患者的1年、3年、5年的肿瘤特异性生存(CSS)率与总体生存(OS)率分别为40.5%、27.3%、24.5%和34.6%、21.3%、17.2%。COX回归分析结果显示T分期、N分期、肿瘤大小、肿瘤原发灶的手术方式及化疗是影响BSCC患者CSS的独立危险因素,而年龄、T分期、N分期、肿瘤大小、肿瘤原发灶的手术方式及化疗是影响BSCC患者OS的独立危险因素(均P<0.05)。Nomogram模型预测1、3、5年患者生存率的Calibration校准曲线与理想曲线具有良好的一致性。CSS的C-index指数为0.752,OS的C-index指数为0.748。结论通过SEER Research Plus数据库可确定年龄、T分期、N分期、肿瘤大小、肿瘤原发灶的手术方式及化疗是影响BSCC患者预后的独立危险因素,以此建立的个体化预测BSCC患者生存预后的Nomogram模型可对不同患者的预后进行个体化精准评估,用于指导临床医师选择合理的治疗方案。展开更多
Nb-22Ti-14Si-2Hf-2Al-xCr （x=2, 6, 10, 14, 17 at%） alloys are prepared by arc-melting under argon atmosphere. Microstructural characteristics, mechanical properties and oxidation resistance of the arc-melted alloys a...Nb-22Ti-14Si-2Hf-2Al-xCr （x=2, 6, 10, 14, 17 at%） alloys are prepared by arc-melting under argon atmosphere. Microstructural characteristics, mechanical properties and oxidation resistance of the arc-melted alloys are investigated. At 2 at% Cr content, the microstructure is composed of Nbss, Nb3Si and a small quantity of Nb5Si3, when the Cr contents increase, Nb3Si disappears. For the high Cr content （x ≥ 10 at%） alloys, besides the Nbss and Nb5Si3, Cr2Nb is also detected. With the increase of Cr content, the volume fractions of Cr2Nb and Nb5Si3 increase, while that of Nbss increases firstly and then begins to degrade when the Cr content is higher than 6 at%. For the alloy with 2 at% Cr, the room temperature fracture toughness is about 14.5 MPa·m1/2, but badly decreases to about 8.5 MPa·m1/2, when the Cr contents increase. Vickers hardness of Nbss tends to increase linearly from about 400 to 500, while that of silicides is not sensitive to Cr contents, about 950. The appearance of Cr2Nb phase significantly improves the high temperature oxidation resistance of the alloys with high Cr contents. The isothermal oxidation tests show that the oxidation kinetics of the alloys with various Cr contents follows parabolic oxidation kinetics.展开更多
文摘The main factors limiting the mass production of TiAl-based components are the high reactivity of TiAl-based alloys with the crucible or mould at high temperature.In this work,various crucibles (e.g.CaO,Y2O3 ceramic crucibles and water-cooled copper crucible) were used to fabricate the Ti-47Al-2Cr-2Nb alloy in a vacuum induction furnace.The effects of crucible materials and melting parameters on the microstructure and mechanical properties of the alloy were analyzed by means of microstructure observation,chemical analysis,tensile test and fracture surface observation.The possibilities of melting TiAl alloys in crucibles made of CaO and Y2O3 refractory materials were also discussed.
文摘目的通过研究膀胱鳞状细胞癌(BSCC)患者的预后独立危险因素,建立可个体化预测BSCC患者生存预后的Nomogram模型。方法收集SEER Research Plus数据库中2000年至2018年诊断为BSCC的1879例患者的临床资料,采用COX回归分析影响BSCC患者预后的独立危险因素,将COX多因素分析所得到的独立危险因素构建成Nomogram模型,采用一致性指数(C-index)和绘制Calibration校准曲线来验证Nomogram模型准确性。结果BSCC患者的1年、3年、5年的肿瘤特异性生存(CSS)率与总体生存(OS)率分别为40.5%、27.3%、24.5%和34.6%、21.3%、17.2%。COX回归分析结果显示T分期、N分期、肿瘤大小、肿瘤原发灶的手术方式及化疗是影响BSCC患者CSS的独立危险因素,而年龄、T分期、N分期、肿瘤大小、肿瘤原发灶的手术方式及化疗是影响BSCC患者OS的独立危险因素(均P<0.05)。Nomogram模型预测1、3、5年患者生存率的Calibration校准曲线与理想曲线具有良好的一致性。CSS的C-index指数为0.752,OS的C-index指数为0.748。结论通过SEER Research Plus数据库可确定年龄、T分期、N分期、肿瘤大小、肿瘤原发灶的手术方式及化疗是影响BSCC患者预后的独立危险因素,以此建立的个体化预测BSCC患者生存预后的Nomogram模型可对不同患者的预后进行个体化精准评估,用于指导临床医师选择合理的治疗方案。
基金National Natural Science Foundation of China (51101005)
文摘Nb-22Ti-14Si-2Hf-2Al-xCr （x=2, 6, 10, 14, 17 at%） alloys are prepared by arc-melting under argon atmosphere. Microstructural characteristics, mechanical properties and oxidation resistance of the arc-melted alloys are investigated. At 2 at% Cr content, the microstructure is composed of Nbss, Nb3Si and a small quantity of Nb5Si3, when the Cr contents increase, Nb3Si disappears. For the high Cr content （x ≥ 10 at%） alloys, besides the Nbss and Nb5Si3, Cr2Nb is also detected. With the increase of Cr content, the volume fractions of Cr2Nb and Nb5Si3 increase, while that of Nbss increases firstly and then begins to degrade when the Cr content is higher than 6 at%. For the alloy with 2 at% Cr, the room temperature fracture toughness is about 14.5 MPa·m1/2, but badly decreases to about 8.5 MPa·m1/2, when the Cr contents increase. Vickers hardness of Nbss tends to increase linearly from about 400 to 500, while that of silicides is not sensitive to Cr contents, about 950. The appearance of Cr2Nb phase significantly improves the high temperature oxidation resistance of the alloys with high Cr contents. The isothermal oxidation tests show that the oxidation kinetics of the alloys with various Cr contents follows parabolic oxidation kinetics.
