Load sharing behavior is very important for power-split gearing system, star gearing reducer as a new type and special transmission system can be used in many industry fields. However, there is few literature regardin...Load sharing behavior is very important for power-split gearing system, star gearing reducer as a new type and special transmission system can be used in many industry fields. However, there is few literature regarding the key multiple-split load sharing issue in main gearbox used in new type geared turbofan engine. Further mechanism anal- ysis are made on load sharing behavior among star gears of star gearing reducer for geared turbofan engine. Compre- hensive meshing error analysis are conducted on eccentricity error, gear thickness error, base pitch error, assembly error, and bearing error of star gearing reducer respectively. Floating meshing error resulting from meshing clearance variation caused by the simultaneous floating of sun gear and annular gear are taken into account. A refined mathematical model for load sharing coefficient calculation is established in consideration of different meshing stiffness and support- ing stiffness for components. The regular curves of load sharing coefficient under the influence of interactions, single action and single variation of various component errors are obtained. The accurate sensitivity of load sharing coefficienttoward different errors is mastered. The load sharing coef- ficient of star gearing reducer is 1.033 and the maximum meshing force in gear tooth is about 3010 N. This paper provides scientific theory evidences for optimal parameter design and proper tolerance distribution in advanced devel- opment and manufacturing process, so as to achieve optimal effects in economy and technology.展开更多
Previous studies indicate that memantine, a low-affinity N-methyI-D-aspartate receptor antagonist exerted acute protective effects against amyloid-β protein-induced neurotoxicity. In the present study, the chronic ef...Previous studies indicate that memantine, a low-affinity N-methyI-D-aspartate receptor antagonist exerted acute protective effects against amyloid-β protein-induced neurotoxicity. In the present study, the chronic effects and mechanisms of memantine were investigated further using electrophysiological methods. The results showed that 7-day intraperitoneal application of memantine, at doses of 5 mg/kg or 20 mg/kg, did not alter hippocampal long-term potentiation induction in rats, while 40 mg/kg memantine presented potent long-term potentiation inhibition. Then further in vitro studys were carried out in 5 mg/kg and 20 mg/kg memantine treated rats. We found that 20 mg/kg memantine attenuated the potent long-term potentiation inhibition caused by exposure to amyloid-β protein in the dentate gyrus in vitro. These findings are the first to demonstrate the antagonizing effect of long-term systematic treatment of memantine against amyloid-β protein triggered long-term potentiation inhibition to improve synaptic plasticity.展开更多
The increasing concentration of greenhouse gases(GHGs)in Earth's atmosphere leads to global warming,which further causes a series of climate changes and does great harm to both human society and natural ecosystems...The increasing concentration of greenhouse gases(GHGs)in Earth's atmosphere leads to global warming,which further causes a series of climate changes and does great harm to both human society and natural ecosystems.Agricultural GHG emissions,mainly in theform of methane(CH4)and nitrous oxide(N2O),areasignificantsourceofGHGs,accountingfor~14%total global GHGs(Zhang et al.,2022).One major source of agricultural GHGs is CH4 emissions from rice paddies,which is responsiblefor~10%-12%ofhuman-inducedCH4emissions(van Groenigen et al.,2013)and contributes~2.40%to the enhanced global warming effect(Zhang et al.,2022).The global warming potential of GHGs emissions from rice systems is roughly four times higher than either wheat or maize(Linquist et al.,2012).展开更多
基金Supported by National Key Technology R&D Program(No.2014BAF08B01)Natural Science Foundation of Tianjin(Grant No.17JCQNJC04300)
文摘Load sharing behavior is very important for power-split gearing system, star gearing reducer as a new type and special transmission system can be used in many industry fields. However, there is few literature regarding the key multiple-split load sharing issue in main gearbox used in new type geared turbofan engine. Further mechanism anal- ysis are made on load sharing behavior among star gears of star gearing reducer for geared turbofan engine. Compre- hensive meshing error analysis are conducted on eccentricity error, gear thickness error, base pitch error, assembly error, and bearing error of star gearing reducer respectively. Floating meshing error resulting from meshing clearance variation caused by the simultaneous floating of sun gear and annular gear are taken into account. A refined mathematical model for load sharing coefficient calculation is established in consideration of different meshing stiffness and support- ing stiffness for components. The regular curves of load sharing coefficient under the influence of interactions, single action and single variation of various component errors are obtained. The accurate sensitivity of load sharing coefficienttoward different errors is mastered. The load sharing coef- ficient of star gearing reducer is 1.033 and the maximum meshing force in gear tooth is about 3010 N. This paper provides scientific theory evidences for optimal parameter design and proper tolerance distribution in advanced devel- opment and manufacturing process, so as to achieve optimal effects in economy and technology.
基金supported by the National Natural Science Foundation of China,No.81070873,30970932Ningbo Natural Science Foundation,No.2011A610065,2010A610072,2011A610064,2011C51006the Scientific Research Fund of Zhejiang Provincial Education Department,No.Y201018164
文摘Previous studies indicate that memantine, a low-affinity N-methyI-D-aspartate receptor antagonist exerted acute protective effects against amyloid-β protein-induced neurotoxicity. In the present study, the chronic effects and mechanisms of memantine were investigated further using electrophysiological methods. The results showed that 7-day intraperitoneal application of memantine, at doses of 5 mg/kg or 20 mg/kg, did not alter hippocampal long-term potentiation induction in rats, while 40 mg/kg memantine presented potent long-term potentiation inhibition. Then further in vitro studys were carried out in 5 mg/kg and 20 mg/kg memantine treated rats. We found that 20 mg/kg memantine attenuated the potent long-term potentiation inhibition caused by exposure to amyloid-β protein in the dentate gyrus in vitro. These findings are the first to demonstrate the antagonizing effect of long-term systematic treatment of memantine against amyloid-β protein triggered long-term potentiation inhibition to improve synaptic plasticity.
基金funded by the Shanghai Agriculture Applied Technology Development Program(T20210104 and G2016060301)the National Key Research and Development Program of China(2018YFE0106200)the Shanghai Natural Science Foundation(20ZR1449300).
文摘The increasing concentration of greenhouse gases(GHGs)in Earth's atmosphere leads to global warming,which further causes a series of climate changes and does great harm to both human society and natural ecosystems.Agricultural GHG emissions,mainly in theform of methane(CH4)and nitrous oxide(N2O),areasignificantsourceofGHGs,accountingfor~14%total global GHGs(Zhang et al.,2022).One major source of agricultural GHGs is CH4 emissions from rice paddies,which is responsiblefor~10%-12%ofhuman-inducedCH4emissions(van Groenigen et al.,2013)and contributes~2.40%to the enhanced global warming effect(Zhang et al.,2022).The global warming potential of GHGs emissions from rice systems is roughly four times higher than either wheat or maize(Linquist et al.,2012).
