Three major elements, carbon, hydrogen, and nitrogen, in twenty-four bituminous coal samples, were measured by laser-induced breakdown spectroscopy. Argon and helium were applied as ambient gas to enhance the signals ...Three major elements, carbon, hydrogen, and nitrogen, in twenty-four bituminous coal samples, were measured by laser-induced breakdown spectroscopy. Argon and helium were applied as ambient gas to enhance the signals and eliminate the interference of nitrogen from surrounding air. The relative standard deviation of the related emission lines and the performance in the partial least squares (PLS) modeling were compared for different ambient environments. The results showed that argon not only improved the intensity, but also reduced signal fluctuation. The PLS model also had the optimal performance in multi-element analysis using argon as ambient gas. The root mean square error of prediction of carbon concentration decreased from 4.25% in air to 3.49% in argon, while the average relative error reduced from 4.96% to 2.98%. Hydrogen line demonstrated similar improvement. Yet, the nitrogen lines were too weak to be detected even in an argon environment which suggested the nitrogen signal measured in air come from the breakdown of nitrogen molecules in the atmosphere.展开更多
近年来,无需复杂样品前处理、且在开放环境下实现离子化的常压敞开式离子化质谱技术(Ambientionization mass spectrometry,AI-MS)的研制与应用成为质谱学领域的前沿及备受关注的研究方向。该文综述了AI离子源的基本原理、特征与应用进...近年来,无需复杂样品前处理、且在开放环境下实现离子化的常压敞开式离子化质谱技术(Ambientionization mass spectrometry,AI-MS)的研制与应用成为质谱学领域的前沿及备受关注的研究方向。该文综述了AI离子源的基本原理、特征与应用进展,并结合笔者研制的空气动力辅助离子化(Air flow assisted ioniza-tion,AFAI)技术,介绍了气流辅助常压敞开式离子化技术的基本特点及其应用。展望了常压敞开式离子化技术的发展趋势。展开更多
To date,the synthesis of crystalline ZnO nanostructures was often performed under high temperatures and/or high pressures with tiny output,which limits their commercial applications.Herein,we report the progress on sy...To date,the synthesis of crystalline ZnO nanostructures was often performed under high temperatures and/or high pressures with tiny output,which limits their commercial applications.Herein,we report the progress on synthesizing single-crystalline ZnO nanosheets under ambient conditions(i.e.,room temperature(RT)and atmospheric pressure)based on a sonochemistry strategy.Furthermore,their controllable growth is accomplished by adjusting the pH values of solutions,enabling the tailored crystal growth habits on the polar-charged faces of ZnO along c-axis.As a proof of concept for their potential applications,the ZnO nanosheets exhibit highly efficient performance for sensing ammonia at RT,with ultrahigh sensitivity(S=610 at 100 ppm),excellent selectivity,rapid detection(response time/recover time=70 s/4 s),and outstanding detection limit down to 0.5 ppm,superior to those of all pure ZnO nanostructures and most ZnO-based composite counterparts ever reported.The present work might open a door for controllable production of ZnO nanostructures under mild conditions,and facilitate the exploration of modern gas sensors for detecting gaseous molecules at RT,which underscores their potential toward practical applications in opto-electronic nanodevices.展开更多
基金Acknowledgements The authors are grateful for the financial support from the National Natural Science Foundation of China (Grant No. 51061130536).
文摘Three major elements, carbon, hydrogen, and nitrogen, in twenty-four bituminous coal samples, were measured by laser-induced breakdown spectroscopy. Argon and helium were applied as ambient gas to enhance the signals and eliminate the interference of nitrogen from surrounding air. The relative standard deviation of the related emission lines and the performance in the partial least squares (PLS) modeling were compared for different ambient environments. The results showed that argon not only improved the intensity, but also reduced signal fluctuation. The PLS model also had the optimal performance in multi-element analysis using argon as ambient gas. The root mean square error of prediction of carbon concentration decreased from 4.25% in air to 3.49% in argon, while the average relative error reduced from 4.96% to 2.98%. Hydrogen line demonstrated similar improvement. Yet, the nitrogen lines were too weak to be detected even in an argon environment which suggested the nitrogen signal measured in air come from the breakdown of nitrogen molecules in the atmosphere.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51972178)Hunan Provincial Innovation Foundation for Postgraduate(Grant No.CX20200454).
文摘To date,the synthesis of crystalline ZnO nanostructures was often performed under high temperatures and/or high pressures with tiny output,which limits their commercial applications.Herein,we report the progress on synthesizing single-crystalline ZnO nanosheets under ambient conditions(i.e.,room temperature(RT)and atmospheric pressure)based on a sonochemistry strategy.Furthermore,their controllable growth is accomplished by adjusting the pH values of solutions,enabling the tailored crystal growth habits on the polar-charged faces of ZnO along c-axis.As a proof of concept for their potential applications,the ZnO nanosheets exhibit highly efficient performance for sensing ammonia at RT,with ultrahigh sensitivity(S=610 at 100 ppm),excellent selectivity,rapid detection(response time/recover time=70 s/4 s),and outstanding detection limit down to 0.5 ppm,superior to those of all pure ZnO nanostructures and most ZnO-based composite counterparts ever reported.The present work might open a door for controllable production of ZnO nanostructures under mild conditions,and facilitate the exploration of modern gas sensors for detecting gaseous molecules at RT,which underscores their potential toward practical applications in opto-electronic nanodevices.