The blue band (BB) in low temperature photoluminescence of Mg-doped GaN films with different Mg concentrations is investigated.The BB peak of as-grown samples with higher Mg concentration centres at lower energy.A shi...The blue band (BB) in low temperature photoluminescence of Mg-doped GaN films with different Mg concentrations is investigated.The BB peak of as-grown samples with higher Mg concentration centres at lower energy.A shift of the BB peak energy is observed after annealing in N2 at different temperatures,meanwhile,the difference between the BB peak energy is observed after annealing in N2 at different temperatures.Meanwhile,the difference between the BB peak energies diminishes for raised annealing temperature,and the BB peaks for different samples converge to 2.92eV after annealing at 850℃.These experimental results can be accounted for by a model based on compensation effect.The shift of BB lines provides a useful criterion for the optimum annealing temperature of the Mg-doped GaN material,and the value is taken to be 850℃ in our case.展开更多
目的优化高效液相色谱-质谱测定尿中苯巯基尿酸(SPMA)方法中的萃取和定量方法。方法尿液采用体积分数50.0%的硫酸进行水解;水解液采用固相萃取柱进行净化,经C18色谱柱分离,串联质谱检测。以同位素标记的SPMA作为内标,以内标工作曲线法...目的优化高效液相色谱-质谱测定尿中苯巯基尿酸(SPMA)方法中的萃取和定量方法。方法尿液采用体积分数50.0%的硫酸进行水解;水解液采用固相萃取柱进行净化,经C18色谱柱分离,串联质谱检测。以同位素标记的SPMA作为内标,以内标工作曲线法定量。结果SPMA的线性范围为0.50~50.00μg/L,相关系数为0.9998;方法的检出限和定量限分别为0.05和0.17μg/L;加标回收率为97.0%~102.0%,批内相对标准偏差(RSD)为0.6%~1.0%,批间RSD为1.7%~6.5%。采用本方法检测,职业性苯接触组人群尿中SPMA质量浓度高于无职业接触组(中位数:2.81 vs 0.28μg/g肌酐,P<0.05)。结论与国家标准方法比较,本方法采用固相萃取和内标法定量,改进后的方法有利于消除基质效应,准确度和精密度好,适用于尿中SPMA的测定。展开更多
文摘The blue band (BB) in low temperature photoluminescence of Mg-doped GaN films with different Mg concentrations is investigated.The BB peak of as-grown samples with higher Mg concentration centres at lower energy.A shift of the BB peak energy is observed after annealing in N2 at different temperatures,meanwhile,the difference between the BB peak energy is observed after annealing in N2 at different temperatures.Meanwhile,the difference between the BB peak energies diminishes for raised annealing temperature,and the BB peaks for different samples converge to 2.92eV after annealing at 850℃.These experimental results can be accounted for by a model based on compensation effect.The shift of BB lines provides a useful criterion for the optimum annealing temperature of the Mg-doped GaN material,and the value is taken to be 850℃ in our case.
文摘目的优化高效液相色谱-质谱测定尿中苯巯基尿酸(SPMA)方法中的萃取和定量方法。方法尿液采用体积分数50.0%的硫酸进行水解;水解液采用固相萃取柱进行净化,经C18色谱柱分离,串联质谱检测。以同位素标记的SPMA作为内标,以内标工作曲线法定量。结果SPMA的线性范围为0.50~50.00μg/L,相关系数为0.9998;方法的检出限和定量限分别为0.05和0.17μg/L;加标回收率为97.0%~102.0%,批内相对标准偏差(RSD)为0.6%~1.0%,批间RSD为1.7%~6.5%。采用本方法检测,职业性苯接触组人群尿中SPMA质量浓度高于无职业接触组(中位数:2.81 vs 0.28μg/g肌酐,P<0.05)。结论与国家标准方法比较,本方法采用固相萃取和内标法定量,改进后的方法有利于消除基质效应,准确度和精密度好,适用于尿中SPMA的测定。
