离子插层已成为提高δ-MnO_(2)作为水系锌离子电池正极材料的循环稳定性和倍率性能的有效策略,但在实践中离子的选择似乎相当随意.本工作选择Cu^(2+)插层δ-MnO_(2),因为Cu^(2+)和Zn^(2+)具有相似的直径,但Cu^(2+)的电负性(1.359)略高于...离子插层已成为提高δ-MnO_(2)作为水系锌离子电池正极材料的循环稳定性和倍率性能的有效策略,但在实践中离子的选择似乎相当随意.本工作选择Cu^(2+)插层δ-MnO_(2),因为Cu^(2+)和Zn^(2+)具有相似的直径,但Cu^(2+)的电负性(1.359)略高于Zn^(2+)(1.347).因此,Cu^(2+)与MnO_(2)晶格具有更强的相互作用,并且在Zn^(2+)和H+的嵌入/脱出循环期间可保持稳定.Cu掺杂的δ-MnO_(2)(CMO)生成了Cu–O键,其电化学性能得到了较大的改善.在2 A g^(-1)的高电流密度下循环600次后,CMO表现出出色的循环稳定性和100%的容量保持率,而原始δ-MnO_(2)的容量保持率仅为23%.当电流密度从0.2增加到2.0 A g^(-1)时,CMO还表现出优异的倍率性能,容量保持率为72%,远高于原始δ-MnO_(2)(32%).由于Cu^(2+)比Zn^(2+)具有更大的电负性,因此Cu–O键作为稳定的“结构之柱”提高了CMO的循环稳定性.Cu^(2+)掺杂还提高了CMO的电子电导率和离子电导率,降低了H+和Zn^(2+)在电极/电解质界面的电荷转移电阻,从而提高了其倍率性能.这项工作为使用插层策略提高电池电化学性能提供了新的见解.展开更多
Grain growth, mechanical properties, and fracture mechanism of nickel-based GH4099 superalloy are investigated using heat treatments, tensile tests, optical microscopy (OM), and scanning electron microscopy (SEM) with...Grain growth, mechanical properties, and fracture mechanism of nickel-based GH4099 superalloy are investigated using heat treatments, tensile tests, optical microscopy (OM), and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS). The OM observation shows that the matrix grains (γ-grains) undergo an apparent growth during the solution treatment. The grain size diameter increases from 100 to 174 μm when the solution temperature rises from 1100℃ to 1160℃ for 30 min. When the holding time increases from 15 to 60 min at 1140℃, the grain size diameter increases from 140 to 176 μm, indicating that the γ-grain growth is more sensitive to temperature than time. Standard deviation, <em>S</em><sub>v</sub>, and the grain size distribution are utilized to characterize the microstructural uniformity. To predict the grain size more accurately, we develop the grain growth kinetics and find that the growth index is close to 5. The yield strength (<em>R</em><sub>p0.2</sub>), tensile strength (<em>R</em><sub>m</sub>), and ductility (<em>A</em><sub>f</sub>) are also measured. It is found that the effect decreases in the order cooling rate, solution temperature, time. <em>R</em><sub>p0.2</sub> reduces by 47% with the increase in the cooling rate from 1℃ to 8000℃/min, while both strength and ductility exhibit little changes with time. The SEM results show that the fracture surfaces have typical mixed brittle and ductile characteristics when specimens are subjected to water quenching and air cooling. However, a complete brittle fracture occurs under furnace cooling conditions. The EDS analysis indicates that the brittle γ' (Ni<sub>3</sub>Ti) phase precipitates around the γ-grain boundary during the slow cooling process, which is the main factor yielding the complete brittle fracture. Finally, the optimal solution treatment scheme for the GH4099 superalloy is proposed—a temperature of 1140℃ for 30 min followed by air cooling.展开更多
目的探讨不同病因的心力衰竭患者的预后。方法选取2009年4月至2014年5月巫山县人民医院收治的458例冠心病和风湿性心脏病导致的心力衰竭住院患者作为研究对象,其中因冠心病导致的心力衰竭患者284例作为冠心病组,174例因风湿性心脏病导...目的探讨不同病因的心力衰竭患者的预后。方法选取2009年4月至2014年5月巫山县人民医院收治的458例冠心病和风湿性心脏病导致的心力衰竭住院患者作为研究对象,其中因冠心病导致的心力衰竭患者284例作为冠心病组,174例因风湿性心脏病导致的心力衰竭住院患者作为风湿性心脏病组。比较两组患者基本资料、累积再住院率、出院后累积病死率及生活质量评分。结果冠心病组患者的年龄、收缩压、舒张压、肌酐和QT间期高于风湿性心脏病组[(71±10)岁比(53±12)岁,(134±21)mm Hg(1 mm Hg=0.133 k Pa)比(116±18)mm Hg,(79±12)mm Hg比(73±11)mm Hg,(112±25)μmol/L比(73±11)μmol/L,(392±54)ms比(367±52)ms],左心室射血分数和心率低于风湿性心脏病组[(34±7)%比(38±5)%,(80±21)次/min比(89±26)次/min](P<0.01)。冠心病组和风湿性心脏病组患者出院后的累积未住院率和生存率呈逐步下降趋势,且冠心病组患者的累积未住院率和生存率低于风湿性心脏病组(P<0.05)。两组患者出院后3、6、12个月的生活质量评分呈上升趋势,风湿性心脏病组患者各时点生活质量评分高于冠心病组(P<0.05)。结论与风湿性心脏病相比,冠心病引起的心力衰竭患者经治疗后预后较差。展开更多
基金supported by Gansu Provincial Natural Science Foundation of China(17JR5RA198 and 21JR7RA470)the Cooperation Project of Gansu Academy of Sciences(2020HZ-2)+3 种基金the Fundamental Research Funds for the Central Universities(lzujbky-2018-119,lzujbky-2018-ct08,and lzujbky-2019-it23)the Key Areas Scientific and Technological Research Projects in Xinjiang Production and Construction Corps(2018AB004)Hubei University of Arts and Science(2020kypytd002)Xiangyang Science and Technology Research and Development(2020YL09)。
文摘离子插层已成为提高δ-MnO_(2)作为水系锌离子电池正极材料的循环稳定性和倍率性能的有效策略,但在实践中离子的选择似乎相当随意.本工作选择Cu^(2+)插层δ-MnO_(2),因为Cu^(2+)和Zn^(2+)具有相似的直径,但Cu^(2+)的电负性(1.359)略高于Zn^(2+)(1.347).因此,Cu^(2+)与MnO_(2)晶格具有更强的相互作用,并且在Zn^(2+)和H+的嵌入/脱出循环期间可保持稳定.Cu掺杂的δ-MnO_(2)(CMO)生成了Cu–O键,其电化学性能得到了较大的改善.在2 A g^(-1)的高电流密度下循环600次后,CMO表现出出色的循环稳定性和100%的容量保持率,而原始δ-MnO_(2)的容量保持率仅为23%.当电流密度从0.2增加到2.0 A g^(-1)时,CMO还表现出优异的倍率性能,容量保持率为72%,远高于原始δ-MnO_(2)(32%).由于Cu^(2+)比Zn^(2+)具有更大的电负性,因此Cu–O键作为稳定的“结构之柱”提高了CMO的循环稳定性.Cu^(2+)掺杂还提高了CMO的电子电导率和离子电导率,降低了H+和Zn^(2+)在电极/电解质界面的电荷转移电阻,从而提高了其倍率性能.这项工作为使用插层策略提高电池电化学性能提供了新的见解.
文摘Grain growth, mechanical properties, and fracture mechanism of nickel-based GH4099 superalloy are investigated using heat treatments, tensile tests, optical microscopy (OM), and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS). The OM observation shows that the matrix grains (γ-grains) undergo an apparent growth during the solution treatment. The grain size diameter increases from 100 to 174 μm when the solution temperature rises from 1100℃ to 1160℃ for 30 min. When the holding time increases from 15 to 60 min at 1140℃, the grain size diameter increases from 140 to 176 μm, indicating that the γ-grain growth is more sensitive to temperature than time. Standard deviation, <em>S</em><sub>v</sub>, and the grain size distribution are utilized to characterize the microstructural uniformity. To predict the grain size more accurately, we develop the grain growth kinetics and find that the growth index is close to 5. The yield strength (<em>R</em><sub>p0.2</sub>), tensile strength (<em>R</em><sub>m</sub>), and ductility (<em>A</em><sub>f</sub>) are also measured. It is found that the effect decreases in the order cooling rate, solution temperature, time. <em>R</em><sub>p0.2</sub> reduces by 47% with the increase in the cooling rate from 1℃ to 8000℃/min, while both strength and ductility exhibit little changes with time. The SEM results show that the fracture surfaces have typical mixed brittle and ductile characteristics when specimens are subjected to water quenching and air cooling. However, a complete brittle fracture occurs under furnace cooling conditions. The EDS analysis indicates that the brittle γ' (Ni<sub>3</sub>Ti) phase precipitates around the γ-grain boundary during the slow cooling process, which is the main factor yielding the complete brittle fracture. Finally, the optimal solution treatment scheme for the GH4099 superalloy is proposed—a temperature of 1140℃ for 30 min followed by air cooling.
文摘目的探讨不同病因的心力衰竭患者的预后。方法选取2009年4月至2014年5月巫山县人民医院收治的458例冠心病和风湿性心脏病导致的心力衰竭住院患者作为研究对象,其中因冠心病导致的心力衰竭患者284例作为冠心病组,174例因风湿性心脏病导致的心力衰竭住院患者作为风湿性心脏病组。比较两组患者基本资料、累积再住院率、出院后累积病死率及生活质量评分。结果冠心病组患者的年龄、收缩压、舒张压、肌酐和QT间期高于风湿性心脏病组[(71±10)岁比(53±12)岁,(134±21)mm Hg(1 mm Hg=0.133 k Pa)比(116±18)mm Hg,(79±12)mm Hg比(73±11)mm Hg,(112±25)μmol/L比(73±11)μmol/L,(392±54)ms比(367±52)ms],左心室射血分数和心率低于风湿性心脏病组[(34±7)%比(38±5)%,(80±21)次/min比(89±26)次/min](P<0.01)。冠心病组和风湿性心脏病组患者出院后的累积未住院率和生存率呈逐步下降趋势,且冠心病组患者的累积未住院率和生存率低于风湿性心脏病组(P<0.05)。两组患者出院后3、6、12个月的生活质量评分呈上升趋势,风湿性心脏病组患者各时点生活质量评分高于冠心病组(P<0.05)。结论与风湿性心脏病相比,冠心病引起的心力衰竭患者经治疗后预后较差。
