After being ingested and entering the human stomach,Helicobacter pylori(H.pylori)adopts several effective strategies to adhere to and colonize the gastric mucosa and move to different regions of the stomach to obtain ...After being ingested and entering the human stomach,Helicobacter pylori(H.pylori)adopts several effective strategies to adhere to and colonize the gastric mucosa and move to different regions of the stomach to obtain more nutrients and escape from the harsher environments of the stomach,leading to acute infection and chronic gastritis,which is the basis of malignant gastric tumors.The endoscopic manifestations and pathological features of H.pylori infection are diverse and vary with the duration of infection.In this review,we describe the endoscopic manifestations of each stage of H.pylori gastritis and then reveal the potential mechanisms of bacterial intragastric colonization and migration from the perspective of endoscopists to provide direction for future research on the effective therapy and management of H.pylori infection.展开更多
The effect of Stokes number on the kinetic energy(KE)budget in particle-laden turbulent channel flows is examined by conducting two-way coupled direct numerical simulations using the Eulerian-Lagrangian approach.The f...The effect of Stokes number on the kinetic energy(KE)budget in particle-laden turbulent channel flows is examined by conducting two-way coupled direct numerical simulations using the Eulerian-Lagrangian approach.The friction Reynolds number of the single phase channel flow is Re_(τ)=180,the particle mass loading and volume fraction areφ_(m)=0.2,φ_(v)≈10−4,and the Stokes numbers range from St^(+)=14–92.The statistics show that due to the presence of solid particles,the mean velocity is reduced in the vicinity of the wall but enhanced in the outer region,and the off-streamwise intensity of fluctuated velocity and the Reynolds stress are reduced in the whole channel.The analysis on the budgets of turbulent kinetic energy(TKE)finds that the presence of particles induces a significant reduction on both the production and dissipation rates.With increasing Stokes number St^(+),both the production and dissipation rates exhibit non-monotonical trends,i.e.,both initially decrease for St^(+)<40 and then transit to growth after St^(+)>40.This suggests that the particle-induced suppression on TKE production and dissipation is the strongest nearly at St^(+)=40.It is also found that particles act as an additional sink/source term in the budgets of both mean-flow kinetic energy(MKE)and TKE.In addition,we investigate the influence of St^(+)on the“zero point”which indicates the balance of exchanging energy between the particle and fluid phases.It is shown that with increasing St^(+),the“zero point”moves toward the wall,suggesting that the position of perfect following between particle and fluid is closer to the wall with larger St^(+).The present results reveal the Stokes number effects on the spatial transport mechanisms of MKE,TKE in turbulent channel flows laden with inertial particles.展开更多
Atmospheric boundary layer(ABL)flow over multiple-hill terrain is studied numerically.The spectral vanishing viscosity(SVV)method is employed for implicit large eddy simulation(ILES).ABL flow over one hill,double hill...Atmospheric boundary layer(ABL)flow over multiple-hill terrain is studied numerically.The spectral vanishing viscosity(SVV)method is employed for implicit large eddy simulation(ILES).ABL flow over one hill,double hills,and three hills are presented in detail.The instantaneous three-dimensional vortex structures,mean velocity,and turbulence intensity in mainstream and vertical directions around the hills are investigated to reveal the main properties of this turbulent flow.During the flow evolution downstream,the Kelvin-Helmholtz vortex,braid vortex,and hairpin vortex are observed sequentially.The turbulence intensity is enhanced around crests and reduced in the recirculation zones.The present results are helpful for understanding the impact of topography on the turbulent flow.The findings can be useful in various fields,such as wind energy,air pollution,and weather forecasting.展开更多
基金Medical Health Science and Technology Development Plan Project of Shandong Province,No.202103030765Natural Science Foundation of Shandong Province,No.ZR2021QH195 and No.ZR2020QH035.
文摘After being ingested and entering the human stomach,Helicobacter pylori(H.pylori)adopts several effective strategies to adhere to and colonize the gastric mucosa and move to different regions of the stomach to obtain more nutrients and escape from the harsher environments of the stomach,leading to acute infection and chronic gastritis,which is the basis of malignant gastric tumors.The endoscopic manifestations and pathological features of H.pylori infection are diverse and vary with the duration of infection.In this review,we describe the endoscopic manifestations of each stage of H.pylori gastritis and then reveal the potential mechanisms of bacterial intragastric colonization and migration from the perspective of endoscopists to provide direction for future research on the effective therapy and management of H.pylori infection.
基金Project supported by the National Nature Science Foundation of China(Grant No.L.69-0401-18-H06).
文摘The effect of Stokes number on the kinetic energy(KE)budget in particle-laden turbulent channel flows is examined by conducting two-way coupled direct numerical simulations using the Eulerian-Lagrangian approach.The friction Reynolds number of the single phase channel flow is Re_(τ)=180,the particle mass loading and volume fraction areφ_(m)=0.2,φ_(v)≈10−4,and the Stokes numbers range from St^(+)=14–92.The statistics show that due to the presence of solid particles,the mean velocity is reduced in the vicinity of the wall but enhanced in the outer region,and the off-streamwise intensity of fluctuated velocity and the Reynolds stress are reduced in the whole channel.The analysis on the budgets of turbulent kinetic energy(TKE)finds that the presence of particles induces a significant reduction on both the production and dissipation rates.With increasing Stokes number St^(+),both the production and dissipation rates exhibit non-monotonical trends,i.e.,both initially decrease for St^(+)<40 and then transit to growth after St^(+)>40.This suggests that the particle-induced suppression on TKE production and dissipation is the strongest nearly at St^(+)=40.It is also found that particles act as an additional sink/source term in the budgets of both mean-flow kinetic energy(MKE)and TKE.In addition,we investigate the influence of St^(+)on the“zero point”which indicates the balance of exchanging energy between the particle and fluid phases.It is shown that with increasing St^(+),the“zero point”moves toward the wall,suggesting that the position of perfect following between particle and fluid is closer to the wall with larger St^(+).The present results reveal the Stokes number effects on the spatial transport mechanisms of MKE,TKE in turbulent channel flows laden with inertial particles.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12372220,12372219,11972220,12072185,91952102 and 12032016).
文摘Atmospheric boundary layer(ABL)flow over multiple-hill terrain is studied numerically.The spectral vanishing viscosity(SVV)method is employed for implicit large eddy simulation(ILES).ABL flow over one hill,double hills,and three hills are presented in detail.The instantaneous three-dimensional vortex structures,mean velocity,and turbulence intensity in mainstream and vertical directions around the hills are investigated to reveal the main properties of this turbulent flow.During the flow evolution downstream,the Kelvin-Helmholtz vortex,braid vortex,and hairpin vortex are observed sequentially.The turbulence intensity is enhanced around crests and reduced in the recirculation zones.The present results are helpful for understanding the impact of topography on the turbulent flow.The findings can be useful in various fields,such as wind energy,air pollution,and weather forecasting.
