文章简单介绍了现代电子烟的发展背景、工作原理以及当下国内外的发展使用趋势。电子烟为控烟而生,但现在越来越多的证据表明电子烟会导致肺损伤。通过查阅国内外文献,对电子烟相关性肺损伤(e-cigarette or vaping product use associat...文章简单介绍了现代电子烟的发展背景、工作原理以及当下国内外的发展使用趋势。电子烟为控烟而生,但现在越来越多的证据表明电子烟会导致肺损伤。通过查阅国内外文献,对电子烟相关性肺损伤(e-cigarette or vaping product use associated lung injury,EVALI)的发病机制、临床特征、疾病诊治与预防进行了整理和分析。EVALI的发病机制尚不明确,现阶段仅能通过患者的电子烟使用史结合影像学与实验室检查的结果来进行临床诊断。患者在确诊后应立即停止使用电子烟并且依照临床表现进行相应的治疗,目前主要的治疗手段包括支持治疗、经验性应用抗菌药物治疗以及早期应用糖皮质激素治疗,出现呼吸窘迫或呼吸衰竭的患者则需住院进行治疗。各国卫生与教育机构应加强对青少年普及电子烟的危害与知识,并通过政策上对电子烟的限制来减少电子烟对群众健康所带来的危害。展开更多
In order to decrease the metallurgical porosity and keyhole-induced porosity during deep penetration laser welding of Al and its alloys, and increase the mechanical properties of work-piece, the effects of welding par...In order to decrease the metallurgical porosity and keyhole-induced porosity during deep penetration laser welding of Al and its alloys, and increase the mechanical properties of work-piece, the effects of welding parameters such as laser power, welding speed and defocusing value on both kinds of porosities were systemically analyzed respectively, and the shape and fluctuation of plume of the keyhole were observed to reflect the stability of the keyhole. The results show that increasing laser power or decreasing laser spot size can lead to the rising of both number and occupied area of pores in the weld; meanwhile, the plume fluctuates violently over the keyhole, which is always companied with the intense metallic vapor, liquid metal spatter and collapsing in the keyhole, thus more pores are generated in the weld. The porosity in the weld reaches the minimum at welding velocity of 2.0 m/min when laser power is 5 kW and defocusing value is 0.展开更多
In this paper, a detailed thermodynamic analysis of the pure low-temperature waste heat recovery generation system is presented. The parameters affecting the system performance are compared to obtain the most signific...In this paper, a detailed thermodynamic analysis of the pure low-temperature waste heat recovery generation system is presented. The parameters affecting the system performance are compared to obtain the most significant ones; furthermore, parameter values are optimized for the largest power generating capability of the system. It is found that the most important parameters are inlet flue gas temperature, steam pressure and the pinch point temperature difference. There is an optimal superheated steam pressure value for giving the maximum generation power per unit flue gas. With the increase of inlet flue gas temperature, the generating power increases and the optimized steam pressure rises as well. However, with increase in pinch point temperature difference, the generating power decreases and the optimized steam pressure decreases as well. The theoretical calculation provides a theoretical basis for the parameters optimization in the design of the pure low-temperature waste heat recovery eeneration swtem展开更多
文摘文章简单介绍了现代电子烟的发展背景、工作原理以及当下国内外的发展使用趋势。电子烟为控烟而生,但现在越来越多的证据表明电子烟会导致肺损伤。通过查阅国内外文献,对电子烟相关性肺损伤(e-cigarette or vaping product use associated lung injury,EVALI)的发病机制、临床特征、疾病诊治与预防进行了整理和分析。EVALI的发病机制尚不明确,现阶段仅能通过患者的电子烟使用史结合影像学与实验室检查的结果来进行临床诊断。患者在确诊后应立即停止使用电子烟并且依照临床表现进行相应的治疗,目前主要的治疗手段包括支持治疗、经验性应用抗菌药物治疗以及早期应用糖皮质激素治疗,出现呼吸窘迫或呼吸衰竭的患者则需住院进行治疗。各国卫生与教育机构应加强对青少年普及电子烟的危害与知识,并通过政策上对电子烟的限制来减少电子烟对群众健康所带来的危害。
基金Project(51204109)supported by the National Natural Science Foundation of China
文摘In order to decrease the metallurgical porosity and keyhole-induced porosity during deep penetration laser welding of Al and its alloys, and increase the mechanical properties of work-piece, the effects of welding parameters such as laser power, welding speed and defocusing value on both kinds of porosities were systemically analyzed respectively, and the shape and fluctuation of plume of the keyhole were observed to reflect the stability of the keyhole. The results show that increasing laser power or decreasing laser spot size can lead to the rising of both number and occupied area of pores in the weld; meanwhile, the plume fluctuates violently over the keyhole, which is always companied with the intense metallic vapor, liquid metal spatter and collapsing in the keyhole, thus more pores are generated in the weld. The porosity in the weld reaches the minimum at welding velocity of 2.0 m/min when laser power is 5 kW and defocusing value is 0.
文摘In this paper, a detailed thermodynamic analysis of the pure low-temperature waste heat recovery generation system is presented. The parameters affecting the system performance are compared to obtain the most significant ones; furthermore, parameter values are optimized for the largest power generating capability of the system. It is found that the most important parameters are inlet flue gas temperature, steam pressure and the pinch point temperature difference. There is an optimal superheated steam pressure value for giving the maximum generation power per unit flue gas. With the increase of inlet flue gas temperature, the generating power increases and the optimized steam pressure rises as well. However, with increase in pinch point temperature difference, the generating power decreases and the optimized steam pressure decreases as well. The theoretical calculation provides a theoretical basis for the parameters optimization in the design of the pure low-temperature waste heat recovery eeneration swtem
