The brown planthopper, Nilaparvata lugens St?l, has become a major threat in tropical Asian and China since the rice green revolution of the 1960 s. Currently, insecticide application remains the primary choice for co...The brown planthopper, Nilaparvata lugens St?l, has become a major threat in tropical Asian and China since the rice green revolution of the 1960 s. Currently, insecticide application remains the primary choice for controlling this rice insect pest, but heavy use of insecticides poses dangerous risks to beneficial natural enemies and pollinators, and stimulates N. lugens reproductivity, and has caused a resurgence of the pest in the major rice-planting regions throughout Asia. Achieving the long-lasting goal of sustainable management of N. lugens requires understanding of the molecular basis of outbreaks of the pest and the development of environment-friendly pest-control strategies. Here, we review the recent molecular advances in N. lugens research on the aspects of its endosymbionts, virus transmission, insecticide resistance, and interaction between N. lugens and rice plants. We also put forward further research directions that may shed some lights on management of the rice pest.展开更多
Quasi-two-dimensi on al(2D)β-Ga2O3 is a rediscovered metal-oxide semiconductor with an ultra-wide bandgap of 4.6-4.9eV.It has been reported to be a promising material for next-generation power and radio frequency ele...Quasi-two-dimensi on al(2D)β-Ga2O3 is a rediscovered metal-oxide semiconductor with an ultra-wide bandgap of 4.6-4.9eV.It has been reported to be a promising material for next-generation power and radio frequency electronics.Field effect transistors(FETs)that can switch at high voltage are key compone nts in power and radio frequency devices,and reliable Ohmic con tacts are essential for high FET performance.However,obtaining low contact resistance onβ-Ga2O3 FETs is difficult since reactions betweenβ-Ga2O3 and metal contacts are not fully understood.Herein,we experimentally demonstrate the importanee of reactions at the metal/β-Ga2O3 interface and the corresponding effects of these reactions on FET performance.When Ti is employed as the metal contact,annealing ofβ-Ga2O3 FETs in argon can effectively transform Schottky contacts into Ohmic contacts and permit a large drain current density of-3.1 mA//μm.The contact resistance(Rcontact)between the Ti electrodes andβ-Ga2O3 decreased from^430 to^0.387Ω·mm after annealing.X-ray photoelectron spectroscopy(XPS)confirmed the formation of oxygen vacancies at the Ti/β-Ga2O3 interface after annealing,which is believed to cause the improved FET performance.The results of this study pave the way for greater application ofβ-Ga2O3 in electronics.展开更多
In this paper, the fluid dynamic performance for a new boat form grooved planing boats is analyzed, and the results of resistance tests for seven grooved planing boat models of different types are presented in the for...In this paper, the fluid dynamic performance for a new boat form grooved planing boats is analyzed, and the results of resistance tests for seven grooved planing boat models of different types are presented in the form of curves of attack angle and resistance-weight ratio versus Froude number. According to these curves, the effect of some parameters of the boat type on the resistance is analyzed.展开更多
基金supported by the National Natural Science Foundation of China(31672025,31471765 and 31630057)
文摘The brown planthopper, Nilaparvata lugens St?l, has become a major threat in tropical Asian and China since the rice green revolution of the 1960 s. Currently, insecticide application remains the primary choice for controlling this rice insect pest, but heavy use of insecticides poses dangerous risks to beneficial natural enemies and pollinators, and stimulates N. lugens reproductivity, and has caused a resurgence of the pest in the major rice-planting regions throughout Asia. Achieving the long-lasting goal of sustainable management of N. lugens requires understanding of the molecular basis of outbreaks of the pest and the development of environment-friendly pest-control strategies. Here, we review the recent molecular advances in N. lugens research on the aspects of its endosymbionts, virus transmission, insecticide resistance, and interaction between N. lugens and rice plants. We also put forward further research directions that may shed some lights on management of the rice pest.
文摘Quasi-two-dimensi on al(2D)β-Ga2O3 is a rediscovered metal-oxide semiconductor with an ultra-wide bandgap of 4.6-4.9eV.It has been reported to be a promising material for next-generation power and radio frequency electronics.Field effect transistors(FETs)that can switch at high voltage are key compone nts in power and radio frequency devices,and reliable Ohmic con tacts are essential for high FET performance.However,obtaining low contact resistance onβ-Ga2O3 FETs is difficult since reactions betweenβ-Ga2O3 and metal contacts are not fully understood.Herein,we experimentally demonstrate the importanee of reactions at the metal/β-Ga2O3 interface and the corresponding effects of these reactions on FET performance.When Ti is employed as the metal contact,annealing ofβ-Ga2O3 FETs in argon can effectively transform Schottky contacts into Ohmic contacts and permit a large drain current density of-3.1 mA//μm.The contact resistance(Rcontact)between the Ti electrodes andβ-Ga2O3 decreased from^430 to^0.387Ω·mm after annealing.X-ray photoelectron spectroscopy(XPS)confirmed the formation of oxygen vacancies at the Ti/β-Ga2O3 interface after annealing,which is believed to cause the improved FET performance.The results of this study pave the way for greater application ofβ-Ga2O3 in electronics.
文摘In this paper, the fluid dynamic performance for a new boat form grooved planing boats is analyzed, and the results of resistance tests for seven grooved planing boat models of different types are presented in the form of curves of attack angle and resistance-weight ratio versus Froude number. According to these curves, the effect of some parameters of the boat type on the resistance is analyzed.
