In the field of dual-pulse laser-induced breakdown spectroscopy(DP-LIBS)research,the pursuit of methods for determining pulse intervals and other parameters quickly and conveniently in order to achieve optimal spectra...In the field of dual-pulse laser-induced breakdown spectroscopy(DP-LIBS)research,the pursuit of methods for determining pulse intervals and other parameters quickly and conveniently in order to achieve optimal spectral signal enhancement is paramount.To aid researchers in identification of optimal signal enhancement conditions and more accurate interpretation of the underlying signal enhancement mechanisms,theoretical simulations of the spatiotemporal processes of coaxial DP-LIBS-induced plasma have been established in this work.Using a model based on laser ablation and two-dimensional axisymmetric fluid dynamics,plasma evolutions during aluminum–magnesium alloy laser ablation under single-pulse and coaxial dualpulse excitations have been simulated.The influences of factors,such as delay time,laser fluence,plasma temperature,and particle number density,on the DP-LIBS spectral signals are investigated.Under pulse intervals ranging from 50 to 1500 ns,the time evolutions of spectral line intensity,dual-pulse emission enhancement relative to the single-pulse results,laser irradiance,spatial distribution of plasma temperature and species number density,as well as laser irradiance shielded by plasma have been obtained.The study indicates that the main reason behind the radiation signal enhancement in coaxial DP-LIBS-induced plasma is attributed to the increased species number density and plasma temperature caused by the second laser,and it is inferred that the shielding effect of the plasma mainly occurs in the boundary layer of the stagnation point flow over the target surface.This research provides a theoretical basis for experimental research,parameter optimization,and signal enhancement tracing in DP-LIBS.展开更多
目的探讨依达拉奉联合脑蛋白水解物治疗老年急性脑梗死的效果,观察其对炎性因子、神经功能恢复的影响。方法将2016年1月至2017年10月因急性脑梗死于本院就诊的82例老年患者纳入研究并据随机数据表法分组。对照组41例予脑蛋白水解物治疗...目的探讨依达拉奉联合脑蛋白水解物治疗老年急性脑梗死的效果,观察其对炎性因子、神经功能恢复的影响。方法将2016年1月至2017年10月因急性脑梗死于本院就诊的82例老年患者纳入研究并据随机数据表法分组。对照组41例予脑蛋白水解物治疗,观察组41例联合依达拉奉注射液治疗,7天后比较两组临床疗效。结果治疗后观察组肿瘤坏死因子(Tumor necrosis factor,TNF-α)、超敏C反应蛋白(Hypersensitive C-reactive protein,Hs-CRP)低于对照组,差异具统计学意义(P<0.05);治疗后观察组日常生活能力(activity of daily living,ADL评分)高于对照组,神经功能评分(Neurological function score,NIHSS评分)低于对照组(P<0.05);观察组总有效率92.68%,高于对照组的73.17%(P<0.05)。结论依达拉奉联合脑蛋白水解物治疗老年急性脑梗死效果显著,可有效改善炎症反应,促进神经功能修复,值得推广。展开更多
基金supported by the National Key R&D Program of China (No. 2017YFA0304203)the National Energy R&D Center of Petroleum Refining Technology (RIPP, SINOPEC)+3 种基金Changjiang Scholars and Innovative Research Team at the University of the Ministry of Education of China (No. IRT_17R70)National Natural Science Foundation of China (NSFC) (Nos. 61975103, 61875108 and 627010407)111 Project (No. D18001)Fund for Shanxi (No. 1331KSC)
文摘In the field of dual-pulse laser-induced breakdown spectroscopy(DP-LIBS)research,the pursuit of methods for determining pulse intervals and other parameters quickly and conveniently in order to achieve optimal spectral signal enhancement is paramount.To aid researchers in identification of optimal signal enhancement conditions and more accurate interpretation of the underlying signal enhancement mechanisms,theoretical simulations of the spatiotemporal processes of coaxial DP-LIBS-induced plasma have been established in this work.Using a model based on laser ablation and two-dimensional axisymmetric fluid dynamics,plasma evolutions during aluminum–magnesium alloy laser ablation under single-pulse and coaxial dualpulse excitations have been simulated.The influences of factors,such as delay time,laser fluence,plasma temperature,and particle number density,on the DP-LIBS spectral signals are investigated.Under pulse intervals ranging from 50 to 1500 ns,the time evolutions of spectral line intensity,dual-pulse emission enhancement relative to the single-pulse results,laser irradiance,spatial distribution of plasma temperature and species number density,as well as laser irradiance shielded by plasma have been obtained.The study indicates that the main reason behind the radiation signal enhancement in coaxial DP-LIBS-induced plasma is attributed to the increased species number density and plasma temperature caused by the second laser,and it is inferred that the shielding effect of the plasma mainly occurs in the boundary layer of the stagnation point flow over the target surface.This research provides a theoretical basis for experimental research,parameter optimization,and signal enhancement tracing in DP-LIBS.
文摘目的探讨依达拉奉联合脑蛋白水解物治疗老年急性脑梗死的效果,观察其对炎性因子、神经功能恢复的影响。方法将2016年1月至2017年10月因急性脑梗死于本院就诊的82例老年患者纳入研究并据随机数据表法分组。对照组41例予脑蛋白水解物治疗,观察组41例联合依达拉奉注射液治疗,7天后比较两组临床疗效。结果治疗后观察组肿瘤坏死因子(Tumor necrosis factor,TNF-α)、超敏C反应蛋白(Hypersensitive C-reactive protein,Hs-CRP)低于对照组,差异具统计学意义(P<0.05);治疗后观察组日常生活能力(activity of daily living,ADL评分)高于对照组,神经功能评分(Neurological function score,NIHSS评分)低于对照组(P<0.05);观察组总有效率92.68%,高于对照组的73.17%(P<0.05)。结论依达拉奉联合脑蛋白水解物治疗老年急性脑梗死效果显著,可有效改善炎症反应,促进神经功能修复,值得推广。
