As an important life support treatment, mechanical ventilation is usually adopted in clinics. With the development of the res-piratory diagnostic and treatment technologies, air flow dynamics of mechanical ventilation...As an important life support treatment, mechanical ventilation is usually adopted in clinics. With the development of the res-piratory diagnostic and treatment technologies, air flow dynamics of mechanical ventilation is usually referenced in the evaluation of pulmonary status and assessment of respiratory therapy. In order to improve the ventilation efficiency and provide a reference for pulmonary diagnostics, in this paper, a new mathematical model of mechanical ventilation system was set up. Furthermore, a prototype mechanical ventilation system for an artificial simulating lung was designed and experimentally studied. Lastly, in order to improve the ventilation efficiency and provide a reference for pulmonary diagnostics, the air flow dynamics of the mechanical ventilation system was illustrated through simulation and experimental studies. The study can be helpful to the optimization of the mechanical ventilation system.展开更多
Experiments carried out using a lung model with a single horizontal bifurcation under different steady inhalation conditions explored the orientation of depositing carbon fibers, and particle deposition frac- tions. T...Experiments carried out using a lung model with a single horizontal bifurcation under different steady inhalation conditions explored the orientation of depositing carbon fibers, and particle deposition frac- tions. The orientations of deposited fibers were obtained from micrographs. Specifically, the effects of the sedimentation parameter （γ）, fiber length, and flow rate on orientations were analyzed. Our results indicate that gravitational effect on deposition cannot be neglected for 0.0228 〈 γ 〈 0.247. The absolute orientation angle of depositing fibers decreased linearly with increasing y for values 0.0228 〈 γ 〈 0.15. Correspondence between Stokes numbers and y suggests these characteristics can be used to estimate fiber deposition in the lower airways. Computer simulations with sphere-equivalent diameter models for the fibers explored deposition efficiency vs. Stokes number. Using the volume-equivalent diameter model, our experimental data for the horizontal bifurcation were replicated. Results for particle deposition using a lung model with a vertical bifurcation indicate that body position also affects deposition.展开更多
The overwhelming magnitude of coal-fired power plants has caused an inevitable release of metal-containing nanoparticles(MNPs)into the atmosphere,which may be inhaled into the respiratory system and cause oxidative st...The overwhelming magnitude of coal-fired power plants has caused an inevitable release of metal-containing nanoparticles(MNPs)into the atmosphere,which may be inhaled into the respiratory system and cause oxidative stress.In this study,MNPs and oxidative potential(OP)were analyzed in<1μm fractions of 56 coal fly ashes collected from Chinese CFPPs.The particle number concentrations(PNCs)of Fe-and Ti-containing NPs,as the dominant MNPs in CFAs,were in the range of 1.5×10^(9)to 9.4×10^(10)and 6.4×10^(8)to 4.1×10^(10)particles/mg,with average particle sizes of 87 and 89 nm,respectively.Average OP values of<1μm fractions were 1.4−2.2 nmol AA min^(−1)μg^(−1)for three simulated lung fluids,which were 2−3 orders of magnitude higher than those of urban atmospheric PM_(2.5).According to structural equation model analysis,metal concentrations in<1μm fractions,PNCs of Fe-/Ti-containing NPs,and their corresponding dissolved Fe/Ti(including NPs with minute sizes)can regulate OP of<1μm fractions in CFAs.Elevated PNCs of MNPs in CFAs can be produced by CFPPs burning low-rank coals and with a low combustion efficiency boiler(e.g.,circulating fluidized-bed boiler).Once entering lung fluids,they likely release more dissolved metals or tiny corresponding NPs,thus generating greater OP.This study provides the first comprehensive investigation of OP generated by MNPs in CFAs.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51575020)
文摘As an important life support treatment, mechanical ventilation is usually adopted in clinics. With the development of the res-piratory diagnostic and treatment technologies, air flow dynamics of mechanical ventilation is usually referenced in the evaluation of pulmonary status and assessment of respiratory therapy. In order to improve the ventilation efficiency and provide a reference for pulmonary diagnostics, in this paper, a new mathematical model of mechanical ventilation system was set up. Furthermore, a prototype mechanical ventilation system for an artificial simulating lung was designed and experimentally studied. Lastly, in order to improve the ventilation efficiency and provide a reference for pulmonary diagnostics, the air flow dynamics of the mechanical ventilation system was illustrated through simulation and experimental studies. The study can be helpful to the optimization of the mechanical ventilation system.
基金We acknowledge the financial support of the Foundation for the National Natural Science Foundation of China （No. 51176035）, and Author of National Excellent Doctoral Dissertation of China （No. 201040）. In addition, financial support was provided to Xiaole Chen under the Research and Innovation Project for College Gradua- tes of Jiangsu Province （CXZZ12_0099）, the Fundamental Research Funds for the Central Universities, China Scholarship Council （No. 201306090085）, and Scientific Research Foundation of Graduate School of Southeast University （No. YBJJ1209）. The experience gained by Xiaole Chen as a CSC-supported Visiting Student in the Computational Multi-Physics Lab （MAE Dept., NC State University, Raleigh, USA） is also acknowledged. Table 3, Figs. 5 and 7 were provided by Josin Tom, based on his spring 2015 course-project report for MAE558. Professor Goodarz Ahmadi at Clarkson Univer- sity （Clarkson, USA） provided advice for our experimental set-up, and Professor Yong Lu at Southeast University provided guidance in programming the image-processing method.
文摘Experiments carried out using a lung model with a single horizontal bifurcation under different steady inhalation conditions explored the orientation of depositing carbon fibers, and particle deposition frac- tions. The orientations of deposited fibers were obtained from micrographs. Specifically, the effects of the sedimentation parameter （γ）, fiber length, and flow rate on orientations were analyzed. Our results indicate that gravitational effect on deposition cannot be neglected for 0.0228 〈 γ 〈 0.247. The absolute orientation angle of depositing fibers decreased linearly with increasing y for values 0.0228 〈 γ 〈 0.15. Correspondence between Stokes numbers and y suggests these characteristics can be used to estimate fiber deposition in the lower airways. Computer simulations with sphere-equivalent diameter models for the fibers explored deposition efficiency vs. Stokes number. Using the volume-equivalent diameter model, our experimental data for the horizontal bifurcation were replicated. Results for particle deposition using a lung model with a vertical bifurcation indicate that body position also affects deposition.
基金study was funded by the National Natural Science Foundation of China(42125102)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB40000000)。
文摘The overwhelming magnitude of coal-fired power plants has caused an inevitable release of metal-containing nanoparticles(MNPs)into the atmosphere,which may be inhaled into the respiratory system and cause oxidative stress.In this study,MNPs and oxidative potential(OP)were analyzed in<1μm fractions of 56 coal fly ashes collected from Chinese CFPPs.The particle number concentrations(PNCs)of Fe-and Ti-containing NPs,as the dominant MNPs in CFAs,were in the range of 1.5×10^(9)to 9.4×10^(10)and 6.4×10^(8)to 4.1×10^(10)particles/mg,with average particle sizes of 87 and 89 nm,respectively.Average OP values of<1μm fractions were 1.4−2.2 nmol AA min^(−1)μg^(−1)for three simulated lung fluids,which were 2−3 orders of magnitude higher than those of urban atmospheric PM_(2.5).According to structural equation model analysis,metal concentrations in<1μm fractions,PNCs of Fe-/Ti-containing NPs,and their corresponding dissolved Fe/Ti(including NPs with minute sizes)can regulate OP of<1μm fractions in CFAs.Elevated PNCs of MNPs in CFAs can be produced by CFPPs burning low-rank coals and with a low combustion efficiency boiler(e.g.,circulating fluidized-bed boiler).Once entering lung fluids,they likely release more dissolved metals or tiny corresponding NPs,thus generating greater OP.This study provides the first comprehensive investigation of OP generated by MNPs in CFAs.
