基于Miller P H雾滴速度模型和离散相模型的粒子跟踪技术,就侧风风速、风幕出风口气流速度和喷雾压力对雾滴漂移的影响展开研究,获得了风幕式喷杆喷雾漂移距离计算方法。同时,利用风幕式喷杆喷雾气液两相流系统试验平台和自制的雾滴承...基于Miller P H雾滴速度模型和离散相模型的粒子跟踪技术,就侧风风速、风幕出风口气流速度和喷雾压力对雾滴漂移的影响展开研究,获得了风幕式喷杆喷雾漂移距离计算方法。同时,利用风幕式喷杆喷雾气液两相流系统试验平台和自制的雾滴承接器进行了与计算相对应的试验研究。对比显示计算与实验结果基本一致,说明该风幕式喷杆喷雾漂移距离计算方法是可行的。计算和试验研究显示:风幕能有效地抑制雾滴漂移现象,在4级风以下(含4级风),风幕式喷杆喷雾机也能正常作业;当无风幕和侧风时,雾滴漂移距离为65~1 7 0 mm;当侧风风速增大至4 m/s时,无风幕情况下雾滴漂移距离增大了5 2.4倍,而当风幕出风口气流速度增大至12.3m/s时,雾滴漂移距离降低至340~390mm。展开更多
BACKGROUND: Acute necrotizing pancreatitis (ANP) leads to a systemic inflammatory response characterized by widespread leukocyte activation and, as a consequence, distant organ injury. The aim of this study was to exp...BACKGROUND: Acute necrotizing pancreatitis (ANP) leads to a systemic inflammatory response characterized by widespread leukocyte activation and, as a consequence, distant organ injury. The aim of this study was to explore the relationship between gastric microcirculatory impairment and inflammatory mediators released in rats and to evaluate the therapeutic effect of ligustrazine extracted from Rhizoma ligusticum wallichii on gastric mucosa injury in a rat model of ANP. METHODS: Ninety-six Sprague-Dawley rats were randomly divided into three groups: normal control (group Q; ANP without treatment (group P); and ANP treated with ligustrazine (group T). The ANP model was induced by injection of 50 g/L sodium taurocholate under the pancreatic membrane (4 ml/kg). Group C was given isovolumetric injection of 9 g/L physiological saline by the same route. Group T was injected with ligustrazine (10 ml/kg) via the portal vein. The radioactive biomicrosphere technique was used to measure the blood flow 2 and 12 hours after the induction of ANP. Samples of the pancreas and stomach were taken to assess pathological changes by a validated histology score; meanwhile, the levels of serum interleukin-1 beta (IL-1 beta) were determined. Gastric tissues were also used to measure the level of myeloperoxidase (MPO), which is expressed intracellularly in the azurophilic granules of neutrophils. RESULTS: Blood flow in group P was significantly lower than that in group C (P < 0.01). Pathological changes were significantly aggravated in group P. The gastric MPO activity in group P was significantly higher than that in group C (P < 0.01). The level of serum IL-1 beta in group P increased more significantly than that in group C (P < 0.01). Blood flow of the stomach in group T was significantly higher than that in group P after 2 hours (P < 0.01). The pathological changes were significantly alleviated in group T. The MPO activity of group T was significantly lower than that of group P (P < 0.01). Although serum IL-1 beta level of group T, was higher than of group C (P < 0.01), it was lower than that of group P (P < 0.01). There was a negative correlation between gastric blood flow and MPO activity (r=-0.983, P < 0.01), and between gastric blood flow and pathological score (r=-0.917, P < 0.05). CONCLUSIONS: Decreased gastric blood flow and increased inflammatory mediators can be seen early in ANP, and both are important factors for gastric and mucosal injury. Ligustrazine can ameliorate microcirculatory disorder and alleviate the damage to the pancreas and stomach.展开更多
基金This study was supported by grants from the Zhenjiang Science and Technology Committee(No.SH2002015and No.SH2005044).
文摘BACKGROUND: Acute necrotizing pancreatitis (ANP) leads to a systemic inflammatory response characterized by widespread leukocyte activation and, as a consequence, distant organ injury. The aim of this study was to explore the relationship between gastric microcirculatory impairment and inflammatory mediators released in rats and to evaluate the therapeutic effect of ligustrazine extracted from Rhizoma ligusticum wallichii on gastric mucosa injury in a rat model of ANP. METHODS: Ninety-six Sprague-Dawley rats were randomly divided into three groups: normal control (group Q; ANP without treatment (group P); and ANP treated with ligustrazine (group T). The ANP model was induced by injection of 50 g/L sodium taurocholate under the pancreatic membrane (4 ml/kg). Group C was given isovolumetric injection of 9 g/L physiological saline by the same route. Group T was injected with ligustrazine (10 ml/kg) via the portal vein. The radioactive biomicrosphere technique was used to measure the blood flow 2 and 12 hours after the induction of ANP. Samples of the pancreas and stomach were taken to assess pathological changes by a validated histology score; meanwhile, the levels of serum interleukin-1 beta (IL-1 beta) were determined. Gastric tissues were also used to measure the level of myeloperoxidase (MPO), which is expressed intracellularly in the azurophilic granules of neutrophils. RESULTS: Blood flow in group P was significantly lower than that in group C (P < 0.01). Pathological changes were significantly aggravated in group P. The gastric MPO activity in group P was significantly higher than that in group C (P < 0.01). The level of serum IL-1 beta in group P increased more significantly than that in group C (P < 0.01). Blood flow of the stomach in group T was significantly higher than that in group P after 2 hours (P < 0.01). The pathological changes were significantly alleviated in group T. The MPO activity of group T was significantly lower than that of group P (P < 0.01). Although serum IL-1 beta level of group T, was higher than of group C (P < 0.01), it was lower than that of group P (P < 0.01). There was a negative correlation between gastric blood flow and MPO activity (r=-0.983, P < 0.01), and between gastric blood flow and pathological score (r=-0.917, P < 0.05). CONCLUSIONS: Decreased gastric blood flow and increased inflammatory mediators can be seen early in ANP, and both are important factors for gastric and mucosal injury. Ligustrazine can ameliorate microcirculatory disorder and alleviate the damage to the pancreas and stomach.
