Phase evolution and magnetic properties of (Nd_o.95La_0.05)9.5-11Febal.M_2B10.5. where M=Cr, Ti, Nb, V, Mo, Zr, Hf, Ta, Mn or W, melt spun ribbons have been investigated. Almost all the alloy ribbons. except for(Nd_0....Phase evolution and magnetic properties of (Nd_o.95La_0.05)9.5-11Febal.M_2B10.5. where M=Cr, Ti, Nb, V, Mo, Zr, Hf, Ta, Mn or W, melt spun ribbons have been investigated. Almost all the alloy ribbons. except for(Nd_0.95La_0.05)_9.5Fe_78M_2B_10.5(M=Mo and Mn),consist merely two magnetic phases, namely α-Fe and R_2Fe_14B, which display a better combination of _iH_c and magnetic energy product. Remanence (Br) and coercivity (i_H_c) values in the range of 8.0 to 9.1 kG and 9.5 to 18.9 kOe. respectively, can be achieved. Among compositions studied, the Ti and W-substitutions were found to be most effective in increasing the Br and i_H_c, respectively. For a fixed refractory metal substitution, namely, M=C_r, Ti or Nb, an increase in the total rare earth concentration resulted in nanocomposites of small grain sizes and a high volume fraction of the R_2Fe_14B phase, leading to an increase in the magnetic properties.展开更多
目的:探讨心房颤动患者伴≥2 s长R-R间期的发生机制。方法:回顾性分析2019年1-12月在厦门大学附属第一医院就诊的369例房颤患者的24 h动态心电图,根据Holter中是否伴有长R-R间期(≥2.0 s)分为病例组(181例)及对照组(188例),并根据长R-R...目的:探讨心房颤动患者伴≥2 s长R-R间期的发生机制。方法:回顾性分析2019年1-12月在厦门大学附属第一医院就诊的369例房颤患者的24 h动态心电图,根据Holter中是否伴有长R-R间期(≥2.0 s)分为病例组(181例)及对照组(188例),并根据长R-R间期出现时间是否与睡眠相关将病例组分为睡眠相关组(122例)和睡眠无关组(59例)。分别比较病例组与对照组及睡眠相关组与睡眠无关组的24 h心率变异性(HRV)指标24 h R-R间期总体标准差(SDNN)、24 h心率减速力(DC)、最短房室结功能不应期(AVNFRP)、AVNFRP变化值及最长R-R间期发生时基础周期条件下的AVNFRP,并对睡眠相关组和睡眠无关组的24 h SDNN 及24 h DC进行白天(06:00-22:00)夜间(22:00-06:00)比较分析。结果:病例组24 h R-R间期总体标准差(SDNN)、24 h DC及AVNFRP变化值均明显高于对照组(P<0.05),最短AVNFRP及最长R-R间期发生时基础周期条件下的AVNFRP均较对照组显著长(P<0.05);睡眠无关组的24 h SDNN、24 h DC及AVNFRP变化值均明显高于睡眠相关组,最短AVNFRP及最长R-R间期发生时基础周期条件下的AVNFRP均较睡眠相关组显著延长(P<0.05);睡眠无关组白天与夜间的SDNN、DC比较差异均无统计学意义(P>0.05),而与睡眠相关组比较,其白天SDNN、DC及夜间SDNN均显著高(P<0.05),夜间DC比较差异均无统计学意义(P>0.05),睡眠相关组白天SDNN、DC均明显低于夜间(P<0.05)。结论:SDNN、DC增高是房颤伴睡眠相关性长R-R间期发生的重要原因,而房室结功能不应期的病理性延长则是房颤伴睡眠无关性长R-R间期发生的重要原因。展开更多
基金National Science Council, Taiwan! under grant !No. NSC-87-2112-M194-005.
文摘Phase evolution and magnetic properties of (Nd_o.95La_0.05)9.5-11Febal.M_2B10.5. where M=Cr, Ti, Nb, V, Mo, Zr, Hf, Ta, Mn or W, melt spun ribbons have been investigated. Almost all the alloy ribbons. except for(Nd_0.95La_0.05)_9.5Fe_78M_2B_10.5(M=Mo and Mn),consist merely two magnetic phases, namely α-Fe and R_2Fe_14B, which display a better combination of _iH_c and magnetic energy product. Remanence (Br) and coercivity (i_H_c) values in the range of 8.0 to 9.1 kG and 9.5 to 18.9 kOe. respectively, can be achieved. Among compositions studied, the Ti and W-substitutions were found to be most effective in increasing the Br and i_H_c, respectively. For a fixed refractory metal substitution, namely, M=C_r, Ti or Nb, an increase in the total rare earth concentration resulted in nanocomposites of small grain sizes and a high volume fraction of the R_2Fe_14B phase, leading to an increase in the magnetic properties.
文摘目的:探讨心房颤动患者伴≥2 s长R-R间期的发生机制。方法:回顾性分析2019年1-12月在厦门大学附属第一医院就诊的369例房颤患者的24 h动态心电图,根据Holter中是否伴有长R-R间期(≥2.0 s)分为病例组(181例)及对照组(188例),并根据长R-R间期出现时间是否与睡眠相关将病例组分为睡眠相关组(122例)和睡眠无关组(59例)。分别比较病例组与对照组及睡眠相关组与睡眠无关组的24 h心率变异性(HRV)指标24 h R-R间期总体标准差(SDNN)、24 h心率减速力(DC)、最短房室结功能不应期(AVNFRP)、AVNFRP变化值及最长R-R间期发生时基础周期条件下的AVNFRP,并对睡眠相关组和睡眠无关组的24 h SDNN 及24 h DC进行白天(06:00-22:00)夜间(22:00-06:00)比较分析。结果:病例组24 h R-R间期总体标准差(SDNN)、24 h DC及AVNFRP变化值均明显高于对照组(P<0.05),最短AVNFRP及最长R-R间期发生时基础周期条件下的AVNFRP均较对照组显著长(P<0.05);睡眠无关组的24 h SDNN、24 h DC及AVNFRP变化值均明显高于睡眠相关组,最短AVNFRP及最长R-R间期发生时基础周期条件下的AVNFRP均较睡眠相关组显著延长(P<0.05);睡眠无关组白天与夜间的SDNN、DC比较差异均无统计学意义(P>0.05),而与睡眠相关组比较,其白天SDNN、DC及夜间SDNN均显著高(P<0.05),夜间DC比较差异均无统计学意义(P>0.05),睡眠相关组白天SDNN、DC均明显低于夜间(P<0.05)。结论:SDNN、DC增高是房颤伴睡眠相关性长R-R间期发生的重要原因,而房室结功能不应期的病理性延长则是房颤伴睡眠无关性长R-R间期发生的重要原因。