Aiming at the issue of sliding ratio,an internal gear pair is proposed which consists of an involute internal gear and a pinion with quadratic curve teeth.Particularly,the contact pattern is point contact and the pini...Aiming at the issue of sliding ratio,an internal gear pair is proposed which consists of an involute internal gear and a pinion with quadratic curve teeth.Particularly,the contact pattern is point contact and the pinion is generated based on an involute gear.The generation method and mathematical models of the gear pair are presented.The sliding ratio is calculated and the general calculation formulas of sliding ratios are developed.Also,the comparison between the involute gear and proposed gear is made.The adaptability of center distance and contact stress are also discussed.In addition,the gear pair was manufactured and inspected according to the exactitude solid model of the gear pair.In order to confirm this model to be effective,the efficiency experiment and the contrast experiment with the involute gear pair were performed.Furthermore,these two types of pinions were analyzed by scanning electron microscope and wear depths were measured by measuring center.The experiment results show that the efficiency of the internal gear pair is stable at a range about 97.1%to 98.6%and wear depth is less than 50%of the involute gear pair.The internal gear pair is expected to have excellent transmission performance.展开更多
Hypoxia and endothelin-1 (ET-1) are associated with constriction of pulmonary vasculature both in vivo and in vitro. However, the role of hypoxia and ET-1 in the vascular remodelling during the development of pulmonar...Hypoxia and endothelin-1 (ET-1) are associated with constriction of pulmonary vasculature both in vivo and in vitro. However, the role of hypoxia and ET-1 in the vascular remodelling during the development of pulmonary hypertension is unclear. This study demonstrated that ET-1(0. 1 nmol/L to 100 nmol/L) increased the [￣3H]thymidine uptake in a dose-dependent manner in cultured bovine pulmonary artery smooth muscle cells(PASMC). which was enhanced by exposing PASMC to hypoxia (2%O2, 93%N2,5%CO2 ). BQ123, the specific antagonist of endothelin receptor subtype A,eliminated the ET-1 medicated proliferation of PASMC and the cooperative effect of hypoxia. Some dilatory drugs could inhibite the mitogenic effect of ET-1. We also observed that hypoxia significantly increased [￣3H] thymidine uptake in PASMC without ET-1 and BQ123 could inhibite this effect. Radioimmunoassay suggested that there was an autocrine of ET-1 in cultured PASMC which was enhanced by hypoxia significantly.展开更多
基金Project(51575062)supported by the National Natural Science Foundation of ChinaProject(SM2014D202)supported by the Fund of Shanghai Key Laboratory of Spacecraft Mechanism,China
文摘Aiming at the issue of sliding ratio,an internal gear pair is proposed which consists of an involute internal gear and a pinion with quadratic curve teeth.Particularly,the contact pattern is point contact and the pinion is generated based on an involute gear.The generation method and mathematical models of the gear pair are presented.The sliding ratio is calculated and the general calculation formulas of sliding ratios are developed.Also,the comparison between the involute gear and proposed gear is made.The adaptability of center distance and contact stress are also discussed.In addition,the gear pair was manufactured and inspected according to the exactitude solid model of the gear pair.In order to confirm this model to be effective,the efficiency experiment and the contrast experiment with the involute gear pair were performed.Furthermore,these two types of pinions were analyzed by scanning electron microscope and wear depths were measured by measuring center.The experiment results show that the efficiency of the internal gear pair is stable at a range about 97.1%to 98.6%and wear depth is less than 50%of the involute gear pair.The internal gear pair is expected to have excellent transmission performance.
文摘Hypoxia and endothelin-1 (ET-1) are associated with constriction of pulmonary vasculature both in vivo and in vitro. However, the role of hypoxia and ET-1 in the vascular remodelling during the development of pulmonary hypertension is unclear. This study demonstrated that ET-1(0. 1 nmol/L to 100 nmol/L) increased the [￣3H]thymidine uptake in a dose-dependent manner in cultured bovine pulmonary artery smooth muscle cells(PASMC). which was enhanced by exposing PASMC to hypoxia (2%O2, 93%N2,5%CO2 ). BQ123, the specific antagonist of endothelin receptor subtype A,eliminated the ET-1 medicated proliferation of PASMC and the cooperative effect of hypoxia. Some dilatory drugs could inhibite the mitogenic effect of ET-1. We also observed that hypoxia significantly increased [￣3H] thymidine uptake in PASMC without ET-1 and BQ123 could inhibite this effect. Radioimmunoassay suggested that there was an autocrine of ET-1 in cultured PASMC which was enhanced by hypoxia significantly.
