AIM: To investigate the clinicopathological factors underlying the ethnic differences of Helicobacter pylori gastritis and cancer.METHODS: We analyzed clinicopathological parameters of gastric biopsies having H pylori...AIM: To investigate the clinicopathological factors underlying the ethnic differences of Helicobacter pylori gastritis and cancer.METHODS: We analyzed clinicopathological parameters of gastric biopsies having H pylori infection that were randomly selected from different ethnic populations including 147 Americans, 149 Japanese, and 181 Koreans.RESULTS: Males were predominant in Japanese and Korean populations (77.9 and 67.4% respectively) in comparison with Americans (48.3%) (P<0.001). H pylori gastritis in Koreans and Japanese was characterized by the predominant antral involvement. In the antrum,neutrophilic infiltration into the proliferative zone of pit, i,e.acute foveolitis, was more frequent in Koreans (82%) than in Japanese (71%) (P<0.05) and Americans (61%) (P<0.001).Interstitial neutrophilic infiltration, intestinal metaplasia and atrophy were also frequent in Koreans and Japanese. In the body, the prevalence of acute foveolitis was not significantly different among the populations while chronic interstitial inflammation and lymphoid follicles were more pronounced in the body of Americans than in the body of others (P<0.01).CONCLUSION: The male-, and antrum-predominant Hpylori gastritis in Koreans and Japanese is compatible with the pattern of sex and topographical distribution of gastric cancer incidence. Our data suggest that persistent acute foveolitis at the proliferative zone is a crucial step in the gastric carcinogenesis.展开更多
Helicobacter pylori(H.pylori)gastritis may progress to high risk gastropathy and cancer.However,the pathological progression has not been characterized in detail.H.pylori induce persistent inflammatory infiltration.Ne...Helicobacter pylori(H.pylori)gastritis may progress to high risk gastropathy and cancer.However,the pathological progression has not been characterized in detail.H.pylori induce persistent inflammatory infiltration.Neutrophils are unique in that they directly infiltrate into foveolar epithelium aiming the proliferative zone specifically.Neutrophilic proliferative zone foveolitis is a critical pathogenic step in H.pylori gastritis inducing intensive epithelial damage.Epithelial cells carrying accumulated genomic damage and mutations show the Malgun(clear)cell change,characterized by large clear nucleus and prominent nucleolus.Malgun cells further undergo atypical changes,showing nuclear folding,coarse chromatin,and multiple nucleoli.The atypical Malgun cell(AMC)change is a novel premalignant condition in high risk gastropathy,which may progress and undergo malignant transformation directly.The pathobiological significance of AMC in gastric carcinogenesis is reviewed.A new diagnosis system of gastritis is proposed based on the critical pathologic steps classifying low and high risk gastritis for separate treatment modality.It is suggested that the regulation of H.pylori-induced neutrophilic foveolitis might be a future therapeutic goal replacing bactericidal antibiotics approach.展开更多
These experimental investigations are designed to study shock wave characteristics and spray structure. Supersonic liq- uid jets injected into ambient fields are empirically studied using projectile impacts in a two-s...These experimental investigations are designed to study shock wave characteristics and spray structure. Supersonic liq- uid jets injected into ambient fields are empirically studied using projectile impacts in a two-stage light gas gun. This study looks primarily at the design of the nozzle assembly, the tip velocity of the high speed jet, the structure of the spray jet and the shock wave generation process. The supersonic liquid jets were visualized using an ultra high-speed camera and the schlieren system for visualization to quantitatively analyze the shock wave angle. The experimental re- sults with straight cone nozzle types and various non-Newtonian fluid viscosities are presented in this paper. The effects of nozzle geometry on the jet behavior are described. The characteristics of the shock wave generation and spray jet structure were found to be significantly related to the nozzle geometry. The expansion gases accelerated the projectile, which had a mass of 6 grams, from 250 m/s. As a result, it was found that the maximum jet velocity appeared in the liquid jet with high viscosity properties. Supersonic liquid jets, which occurred at the leading edge the shock waves and the compression waves in front of the jets, were observed. Also, the shock waves significantly affected the atomization process for each spray droplet.展开更多
Gel propulsion systems have many advantages with respect to high performance, the energy management of liquid propulsion systems, storability, high density impulse, and low leakage of liquid propellants. The atomizati...Gel propulsion systems have many advantages with respect to high performance, the energy management of liquid propulsion systems, storability, high density impulse, and low leakage of liquid propellants. The atomization process provides sufficient contact surface area between the gelled fuel and oxidizer jets. It is important to study how injection characteristics of gelled propellants are related with break-up and spray distribution. The break-up and mixing processes are very important in achieving maximum efficiency and necessitate the careful study of combustion instability. Gelled propellants are non-Newtonian fluids in which the viscosity is a function of the shear rate, and they have a high dynamic shear viscosity which depends on the amount of gelling agent contents. The present study has focused on the break-up process, wave development of ligament and liquid sheets formed by impinging jets with various gelling agent contents. Especially, the break-up processes of the impinging jets at the initial conditions are studied. The break-up process of like-on-like doublet impinging jets are experimentally characterized using non-Newtonian liquids which are mixed by ionized water 98.5 wt%, Carbopol 941 0.5wt% or 1.0wt%, and NaOH(concentration 10%) 1.0wt%. For the like-on-like doublet injector, the generation of a liquid sheet at the impinging point of two jets was observed. The spray shape with elliptical pattern is distributed in a perpendicular direction to the momentum vectors of the jets. Gelled propellant simulants with high viscosity jets are more stable and produce less pronounced surface waves than low viscosity jets. Generally, the break-up length decreased due to the increasing Reynolds number. However, surface waves and atomized droplets increased. Gelled propellant simulants from like-on-like doublet impinging jets have the spray shape of closed rim patterns at low pressure. Also, the rim patterns of spray have no disturbances on the spray sheet. As the injection pressure increased, rimless patterns which were composed of ligament sheets and small droplets emerged due to the effect of the aerodynamic action. Periodic wave-like structures observed from the near impingement point and atomized droplets were observed at a location further downstream.展开更多
Penetration depth,spray dispersion angle,droplet sizes in breakup processes and atomization processes are very important parameters in combustor of air-breathing engine.These processes will enhance air/fuel mixing ins...Penetration depth,spray dispersion angle,droplet sizes in breakup processes and atomization processes are very important parameters in combustor of air-breathing engine.These processes will enhance air/fuel mixing inside the combustor.Experimental results from the pulsed air-assist liquid jet injected into a cross-flow are investigated.And experiments were conducted to a range of cross-flow velocities from 42~136 m/s.Air is injected with 0~300kPa,with air-assist pulsation frequency of 0~20Hz.Pulsation frequency was modulated by solenoid valve.Phase Doppler Particle Analyzer(PDPA) was utilized to quantitatively measuring droplet characteristics.High-speed CCD camera was used to obtain injected spray structure.Pulsed air-assist liquid jet will offer rapid mixing and good liquid jet penetration.Air-assist makes a very fine droplet which generated mist-like spray.Pulsed air-assist liquid jet will introduce additional supplementary turbulent mixing and control of penetration depth into a cross-flow field.The results show that pulsation frequency has an effect on penetration,transverse velocities and droplet sizes.The experimental data generated in these studies are used for a development of active control strategies to optimize the liquid jet penetration in subsonic cross-flow conditions and predict combustion low frequency instability.展开更多
Spray structure and atomization characteristics were investigated through a comparison of a porous and a shear coaxial injector. The porous injector shows better atomization performance than the shear coaxial injector...Spray structure and atomization characteristics were investigated through a comparison of a porous and a shear coaxial injector. The porous injector shows better atomization performance than the shear coaxial injector. To increase atomization performance and mixing efficiency of two-phase jets, a coaxial porous injector which can be applicable to liquid rocket combustors was designed and tested. The characteristics of atomization and spray from a porous and a shear coaxial injector were characterized by the momentum flux ratio. The breakup mechanism of the porous injector is governed by Taylor-Culick flow and axial shear forces. Momentum of injected gas flow through a porous material which is composed of sintered metal is radically transferred to the center of the liquid column, and then liquid column is effectively broken up. Although the shapes of spray from porous and shear coaxial jets were similar for various momentum ratio, spray structures such as spray angle and droplet sizes were different. As increasing the momentum flux ratio, SMD from the porous injector showed smaller value than the shear coaxial展开更多
基金Supported by Joint Korean-Israeli Research Grant by the Korean Ministry of Science and Technology.M6-0025-00-0002-02-A01-00- 002-00
文摘AIM: To investigate the clinicopathological factors underlying the ethnic differences of Helicobacter pylori gastritis and cancer.METHODS: We analyzed clinicopathological parameters of gastric biopsies having H pylori infection that were randomly selected from different ethnic populations including 147 Americans, 149 Japanese, and 181 Koreans.RESULTS: Males were predominant in Japanese and Korean populations (77.9 and 67.4% respectively) in comparison with Americans (48.3%) (P<0.001). H pylori gastritis in Koreans and Japanese was characterized by the predominant antral involvement. In the antrum,neutrophilic infiltration into the proliferative zone of pit, i,e.acute foveolitis, was more frequent in Koreans (82%) than in Japanese (71%) (P<0.05) and Americans (61%) (P<0.001).Interstitial neutrophilic infiltration, intestinal metaplasia and atrophy were also frequent in Koreans and Japanese. In the body, the prevalence of acute foveolitis was not significantly different among the populations while chronic interstitial inflammation and lymphoid follicles were more pronounced in the body of Americans than in the body of others (P<0.01).CONCLUSION: The male-, and antrum-predominant Hpylori gastritis in Koreans and Japanese is compatible with the pattern of sex and topographical distribution of gastric cancer incidence. Our data suggest that persistent acute foveolitis at the proliferative zone is a crucial step in the gastric carcinogenesis.
基金Supported by Doyak Research Program(2009-79398)through National Research Foundation grant funded by the Ministry of science,ICT,and Future Planning
文摘Helicobacter pylori(H.pylori)gastritis may progress to high risk gastropathy and cancer.However,the pathological progression has not been characterized in detail.H.pylori induce persistent inflammatory infiltration.Neutrophils are unique in that they directly infiltrate into foveolar epithelium aiming the proliferative zone specifically.Neutrophilic proliferative zone foveolitis is a critical pathogenic step in H.pylori gastritis inducing intensive epithelial damage.Epithelial cells carrying accumulated genomic damage and mutations show the Malgun(clear)cell change,characterized by large clear nucleus and prominent nucleolus.Malgun cells further undergo atypical changes,showing nuclear folding,coarse chromatin,and multiple nucleoli.The atypical Malgun cell(AMC)change is a novel premalignant condition in high risk gastropathy,which may progress and undergo malignant transformation directly.The pathobiological significance of AMC in gastric carcinogenesis is reviewed.A new diagnosis system of gastritis is proposed based on the critical pathologic steps classifying low and high risk gastritis for separate treatment modality.It is suggested that the regulation of H.pylori-induced neutrophilic foveolitis might be a future therapeutic goal replacing bactericidal antibiotics approach.
文摘These experimental investigations are designed to study shock wave characteristics and spray structure. Supersonic liq- uid jets injected into ambient fields are empirically studied using projectile impacts in a two-stage light gas gun. This study looks primarily at the design of the nozzle assembly, the tip velocity of the high speed jet, the structure of the spray jet and the shock wave generation process. The supersonic liquid jets were visualized using an ultra high-speed camera and the schlieren system for visualization to quantitatively analyze the shock wave angle. The experimental re- sults with straight cone nozzle types and various non-Newtonian fluid viscosities are presented in this paper. The effects of nozzle geometry on the jet behavior are described. The characteristics of the shock wave generation and spray jet structure were found to be significantly related to the nozzle geometry. The expansion gases accelerated the projectile, which had a mass of 6 grams, from 250 m/s. As a result, it was found that the maximum jet velocity appeared in the liquid jet with high viscosity properties. Supersonic liquid jets, which occurred at the leading edge the shock waves and the compression waves in front of the jets, were observed. Also, the shock waves significantly affected the atomization process for each spray droplet.
基金(Grants No. 00040486) was supported by Business for Cooperative R&D between Industry, AcademyResearch Institute funded Korea Small and Medium Business Administration in 2010
文摘Gel propulsion systems have many advantages with respect to high performance, the energy management of liquid propulsion systems, storability, high density impulse, and low leakage of liquid propellants. The atomization process provides sufficient contact surface area between the gelled fuel and oxidizer jets. It is important to study how injection characteristics of gelled propellants are related with break-up and spray distribution. The break-up and mixing processes are very important in achieving maximum efficiency and necessitate the careful study of combustion instability. Gelled propellants are non-Newtonian fluids in which the viscosity is a function of the shear rate, and they have a high dynamic shear viscosity which depends on the amount of gelling agent contents. The present study has focused on the break-up process, wave development of ligament and liquid sheets formed by impinging jets with various gelling agent contents. Especially, the break-up processes of the impinging jets at the initial conditions are studied. The break-up process of like-on-like doublet impinging jets are experimentally characterized using non-Newtonian liquids which are mixed by ionized water 98.5 wt%, Carbopol 941 0.5wt% or 1.0wt%, and NaOH(concentration 10%) 1.0wt%. For the like-on-like doublet injector, the generation of a liquid sheet at the impinging point of two jets was observed. The spray shape with elliptical pattern is distributed in a perpendicular direction to the momentum vectors of the jets. Gelled propellant simulants with high viscosity jets are more stable and produce less pronounced surface waves than low viscosity jets. Generally, the break-up length decreased due to the increasing Reynolds number. However, surface waves and atomized droplets increased. Gelled propellant simulants from like-on-like doublet impinging jets have the spray shape of closed rim patterns at low pressure. Also, the rim patterns of spray have no disturbances on the spray sheet. As the injection pressure increased, rimless patterns which were composed of ligament sheets and small droplets emerged due to the effect of the aerodynamic action. Periodic wave-like structures observed from the near impingement point and atomized droplets were observed at a location further downstream.
基金supported by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD,Basic Research Promotion Fund) (KRF-2007-D00084)
文摘Penetration depth,spray dispersion angle,droplet sizes in breakup processes and atomization processes are very important parameters in combustor of air-breathing engine.These processes will enhance air/fuel mixing inside the combustor.Experimental results from the pulsed air-assist liquid jet injected into a cross-flow are investigated.And experiments were conducted to a range of cross-flow velocities from 42~136 m/s.Air is injected with 0~300kPa,with air-assist pulsation frequency of 0~20Hz.Pulsation frequency was modulated by solenoid valve.Phase Doppler Particle Analyzer(PDPA) was utilized to quantitatively measuring droplet characteristics.High-speed CCD camera was used to obtain injected spray structure.Pulsed air-assist liquid jet will offer rapid mixing and good liquid jet penetration.Air-assist makes a very fine droplet which generated mist-like spray.Pulsed air-assist liquid jet will introduce additional supplementary turbulent mixing and control of penetration depth into a cross-flow field.The results show that pulsation frequency has an effect on penetration,transverse velocities and droplet sizes.The experimental data generated in these studies are used for a development of active control strategies to optimize the liquid jet penetration in subsonic cross-flow conditions and predict combustion low frequency instability.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean Government(MEST)(NRF-2011-0015435 and NRF-2012M 1A3A3A02033146)
文摘Spray structure and atomization characteristics were investigated through a comparison of a porous and a shear coaxial injector. The porous injector shows better atomization performance than the shear coaxial injector. To increase atomization performance and mixing efficiency of two-phase jets, a coaxial porous injector which can be applicable to liquid rocket combustors was designed and tested. The characteristics of atomization and spray from a porous and a shear coaxial injector were characterized by the momentum flux ratio. The breakup mechanism of the porous injector is governed by Taylor-Culick flow and axial shear forces. Momentum of injected gas flow through a porous material which is composed of sintered metal is radically transferred to the center of the liquid column, and then liquid column is effectively broken up. Although the shapes of spray from porous and shear coaxial jets were similar for various momentum ratio, spray structures such as spray angle and droplet sizes were different. As increasing the momentum flux ratio, SMD from the porous injector showed smaller value than the shear coaxial