As the size of satellites scales down, low-power and compact propulsion systems such as the pulsed plasma thruster(PPT) are needed for stabilizing these miniature satellites in orbit. Most PPT systems are operated at ...As the size of satellites scales down, low-power and compact propulsion systems such as the pulsed plasma thruster(PPT) are needed for stabilizing these miniature satellites in orbit. Most PPT systems are operated at 2 J or more of discharge energy. In this work, the performance of a PPT with a side-fed, tongue-flared electrode configuration operated within a lower discharge energy range of 0.5-2.5 J has been investigated. Ablation and charring of the polytetrafluoroethylene propellant surface were analyzed through field-effect scanning electron microscopy imaging and energy-dispersive X-ray spectroscopy. When the discharge energy fell below 2 J, inconsistencies occurred in the specific impulse and the thrust efficiency due to the measurement of the low mass bit. At energy ≥2 J, the performance parameters are compared with other PPT systems of similar configuration and discussed in depth.展开更多
目的:基于表皮生长因子受体(EGFR)/两面神激酶1(JAK1)/信号传导与转录激活因子1(STAT1)信号通路探讨柴芍六君汤治疗慢性萎缩性胃炎(C A G)肝郁脾虚证大鼠的机制。方法:采用化学药物诱导配合饥饱失常及夹尾刺激法建立C A G肝郁脾虚证大...目的:基于表皮生长因子受体(EGFR)/两面神激酶1(JAK1)/信号传导与转录激活因子1(STAT1)信号通路探讨柴芍六君汤治疗慢性萎缩性胃炎(C A G)肝郁脾虚证大鼠的机制。方法:采用化学药物诱导配合饥饱失常及夹尾刺激法建立C A G肝郁脾虚证大鼠模型,将成模大鼠按随机数表法分为模型组、维酶素组(240 mg·kg^(-1)·d^(-1))和柴芍六君汤组(5.1 g·kg^(-1)·d^(-1)),灌胃给药28 d后取材。HE染色观察胃黏膜组织病理改变;ELISA检测血清白细胞介素(IL)-6及IL-1β含量;q-PCR和Western Blot检测胃黏膜组织EGFR/JAK1/STAT1信号通路的mRNA和蛋白表达水平。结果:模型大鼠胃黏膜组织固有层腺体萎缩、减少、排列紊乱,炎症细胞浸润明显,主、壁细胞丢失;与正常组比较,模型组血清IL-6、IL-1β含量显著升高(P<0.01);胃黏膜组织EGFR、JAK1、STAT1 mRNA及蛋白水平升高(P<0.05,P<0.01)。与模型组比较,柴芍六君汤能够减轻CAG肝郁脾虚证大鼠胃黏膜组织固有层腺体萎缩及炎症细胞浸润,降低血清IL-6、IL-1β和下调胃黏膜组织EGFR、JAK1、STAT1 mRNA及蛋白表达水平(P<0.05,P<0.01),整体作用优于维酶素。结论:柴芍六君汤能够改善CAG肝郁脾虚证大鼠胃黏膜组织病理形态,下调炎症因子水平,其机制可能与EGFR/JAK1/STAT1信号通路抑制有关。展开更多
基金supported by the Ministry of Science,Technology and Innovation,Malaysia(MOSTI)(No.04-02-12-SF0339)。
文摘As the size of satellites scales down, low-power and compact propulsion systems such as the pulsed plasma thruster(PPT) are needed for stabilizing these miniature satellites in orbit. Most PPT systems are operated at 2 J or more of discharge energy. In this work, the performance of a PPT with a side-fed, tongue-flared electrode configuration operated within a lower discharge energy range of 0.5-2.5 J has been investigated. Ablation and charring of the polytetrafluoroethylene propellant surface were analyzed through field-effect scanning electron microscopy imaging and energy-dispersive X-ray spectroscopy. When the discharge energy fell below 2 J, inconsistencies occurred in the specific impulse and the thrust efficiency due to the measurement of the low mass bit. At energy ≥2 J, the performance parameters are compared with other PPT systems of similar configuration and discussed in depth.
