Worldwide, scarce water resources and substantial food demands require efficient water use and high yield.This study investigated whether irrigation frequency can be used to adjust soil moisture to increase grain yiel...Worldwide, scarce water resources and substantial food demands require efficient water use and high yield.This study investigated whether irrigation frequency can be used to adjust soil moisture to increase grain yield and water use efficiency(WUE) of high-yield maize under conditions of mulching and drip irrigation.A field experiment was conducted using three irrigation intervals in 2016: 6, 9, and 12 days(labeled D6, D9, and D12) and five irrigation intervals in 2017: 3, 6, 9, 12, and 15 days(D3, D6, D9, D12, and D15).In Xinjiang, an optimal irrigation quota is 540 mm for high-yield maize.The D3, D6, D9, D12, and D15 irrigation intervals gave grain yields of 19.7, 19.1–21.0, 18.8–20.0, 18.2–19.2, and 17.2 Mg ha^-1 and a WUE of 2.48, 2.53–2.80, 2.47–2.63, 2.34–2.45, and 2.08 kg m-3, respectively.Treatment D6 led to the highest soil water storage, but evapotranspiration and soil-water evaporation were lower than other treatments.These results show that irrigation interval D6 can help maintain a favorable soil-moisture environment in the upper-60-cm soil layer, reduce soilwater evaporation and evapotranspiration, and produce the highest yield and WUE.In this arid region and in other regions with similar soil and climate conditions, a similar irrigation interval would thus be beneficial for adjusting soil moisture to increase maize yield and WUE under conditions of mulching and drip irrigation.展开更多
A series of metamorphic high electron mobility transistors （MMHEMTs） with different Ⅴ/Ⅲ flux ratios are grown on CaAs （001） substrates by molecular beam epitaxy （MBE）. The samples are analysed by using atomic ...A series of metamorphic high electron mobility transistors （MMHEMTs） with different Ⅴ/Ⅲ flux ratios are grown on CaAs （001） substrates by molecular beam epitaxy （MBE）. The samples are analysed by using atomic force microscopy （AFM）, Hall measurement, and low temperature photoluminescence （PL）. The optimum Ⅴ/Ⅲ ratio in a range from 15 to 60 for the growth of MMHEMTs is found to be around 40. At this ratio, the root mean square （RMS） roughness of the material is only 2.02 nm; a room-temperature mobility and a sheet electron density are obtained to be 10610.0cm^2/（V.s） and 3.26×10^12cm^-2 respectively. These results are equivalent to those obtained for the same structure grown on InP substrate. There are two peaks in the PL spectrum of the structure, corresponding to two sub-energy levels of the In0.53Ga0.47As quantum well. It is found that the photoluminescence intensities of the two peaks vary with the Ⅴ/Ⅲ ratio, for which the reasons are discussed.展开更多
Geometries, energies, and vibrational frequencies for two C4N12O4 isomers with pagodane- and isopagodane-like structures have been calculated at the B3LYP/6-31G＊ level.Isomers 1 and 2 are of D2h and D2d symmetry, res...Geometries, energies, and vibrational frequencies for two C4N12O4 isomers with pagodane- and isopagodane-like structures have been calculated at the B3LYP/6-31G＊ level.Isomers 1 and 2 are of D2h and D2d symmetry, respectively. Heats of formation for the two C4N12O4 isomers have been estimated in this paper, indicating they would be reasonable candidates for high energy density materials.展开更多
The electronic structure characters are calculated for the Zn1-∞MxO alloys with some Zn atoms in ZnO substituted by 3d transition-metal atoms （M）, in order to find out which of these alloys could provide an interme...The electronic structure characters are calculated for the Zn1-∞MxO alloys with some Zn atoms in ZnO substituted by 3d transition-metal atoms （M）, in order to find out which of these alloys could provide an intermediate band material used for fabricating high efficiency solar cell. Especially, among of these alloys, the electronic structure character and optical performance of Zn1-xCr∞ 0 alloys clearly show an intermediate band filled partially and isolated from the VB and the CB in energy band structure of ZnO host, and the intermediate band characters can be preserved with increasing Cr concentrations no more than 8.33% in Zn1-xCrxO alloys, at the same time, the ratio 0.52 of Eg^FC to EVE in Zn1-xCrxO, （x = 4.16%） alloy is closest to the optimal ratio of 0,57. Besides, compared to the ZnO, the optical absorption does indicate a great improved absorption below the calculated band gap of the ZnO and an enhancement of the optical absorption in the whole solar spectral energy range.展开更多
Nighttime enhancements in ionospheric electron density at mid- and low-latitudes are investigated by using the critical frequency of the F2-1ayer （foF2） data measured from ionosonde stations at Okinawa （26.3°N...Nighttime enhancements in ionospheric electron density at mid- and low-latitudes are investigated by using the critical frequency of the F2-1ayer （foF2） data measured from ionosonde stations at Okinawa （26.3°N, 127.8°E, Geomagnetic 15.3°N）, Yamagawa （31.2°N, 130.6°E, Geomagnetic 20.4°N）, Kokubunji （35.7°N, 139.5°E, Geomagnetic 25.5°N）, and Wakkanai （45.4°N, 141.7°E, Geomagnetic 35.4°N） in East Asia during several solar cycles. The results show that there are obvious seasonal and solar activity dependencies of the nighttime electron density enhancements. The enhancements are termed pre-midnight enhancement and post-midnight enhancement, according to the local time when the enhancement appeared. The former has a higher occurrence probability in summer months than in winter months. In contrast, the latter has a larger occurrence probability in winter months than in summer months. Moreover, the nighttime enhancements in electron density are more likely to occur at lower solar activity. These seasonal and solar activity variations of the nighttime enhancements in electron density can be explained in terms of the combined effects of downward plasma flux from the plasmasphere and the neutral winds.展开更多
基金research support from the National Key Research and Development Program of China (2016YFD0300110, 2016YFD0300101)the National Basic Research Program of China (2015CB150401)+2 种基金the National Natural Science Foundation of China (31360302)the Science and Technology Program of the Sixth Division of Xinjiang Construction Corps in China (1703)the Agricultural Science and Technology Innovation Program for financial support.
文摘Worldwide, scarce water resources and substantial food demands require efficient water use and high yield.This study investigated whether irrigation frequency can be used to adjust soil moisture to increase grain yield and water use efficiency(WUE) of high-yield maize under conditions of mulching and drip irrigation.A field experiment was conducted using three irrigation intervals in 2016: 6, 9, and 12 days(labeled D6, D9, and D12) and five irrigation intervals in 2017: 3, 6, 9, 12, and 15 days(D3, D6, D9, D12, and D15).In Xinjiang, an optimal irrigation quota is 540 mm for high-yield maize.The D3, D6, D9, D12, and D15 irrigation intervals gave grain yields of 19.7, 19.1–21.0, 18.8–20.0, 18.2–19.2, and 17.2 Mg ha^-1 and a WUE of 2.48, 2.53–2.80, 2.47–2.63, 2.34–2.45, and 2.08 kg m-3, respectively.Treatment D6 led to the highest soil water storage, but evapotranspiration and soil-water evaporation were lower than other treatments.These results show that irrigation interval D6 can help maintain a favorable soil-moisture environment in the upper-60-cm soil layer, reduce soilwater evaporation and evapotranspiration, and produce the highest yield and WUE.In this arid region and in other regions with similar soil and climate conditions, a similar irrigation interval would thus be beneficial for adjusting soil moisture to increase maize yield and WUE under conditions of mulching and drip irrigation.
文摘A series of metamorphic high electron mobility transistors （MMHEMTs） with different Ⅴ/Ⅲ flux ratios are grown on CaAs （001） substrates by molecular beam epitaxy （MBE）. The samples are analysed by using atomic force microscopy （AFM）, Hall measurement, and low temperature photoluminescence （PL）. The optimum Ⅴ/Ⅲ ratio in a range from 15 to 60 for the growth of MMHEMTs is found to be around 40. At this ratio, the root mean square （RMS） roughness of the material is only 2.02 nm; a room-temperature mobility and a sheet electron density are obtained to be 10610.0cm^2/（V.s） and 3.26×10^12cm^-2 respectively. These results are equivalent to those obtained for the same structure grown on InP substrate. There are two peaks in the PL spectrum of the structure, corresponding to two sub-energy levels of the In0.53Ga0.47As quantum well. It is found that the photoluminescence intensities of the two peaks vary with the Ⅴ/Ⅲ ratio, for which the reasons are discussed.
基金This work was supported by the Natural Science Foundation of Shandong Province (Y2002G11)
文摘Geometries, energies, and vibrational frequencies for two C4N12O4 isomers with pagodane- and isopagodane-like structures have been calculated at the B3LYP/6-31G＊ level.Isomers 1 and 2 are of D2h and D2d symmetry, respectively. Heats of formation for the two C4N12O4 isomers have been estimated in this paper, indicating they would be reasonable candidates for high energy density materials.
基金Supported by the State Key Program for Basic Research of China under Grant No.2006CB921803Project of High Technology Research&Development of China(Project No.2007AA03Z404)+1 种基金National Natural Science Foundation of China under Grant Nos.61274058,60990312,and 61025020Natural Science Foundation of Anhui Province under Grant No.1208085QF116
文摘The electronic structure characters are calculated for the Zn1-∞MxO alloys with some Zn atoms in ZnO substituted by 3d transition-metal atoms （M）, in order to find out which of these alloys could provide an intermediate band material used for fabricating high efficiency solar cell. Especially, among of these alloys, the electronic structure character and optical performance of Zn1-xCr∞ 0 alloys clearly show an intermediate band filled partially and isolated from the VB and the CB in energy band structure of ZnO host, and the intermediate band characters can be preserved with increasing Cr concentrations no more than 8.33% in Zn1-xCrxO alloys, at the same time, the ratio 0.52 of Eg^FC to EVE in Zn1-xCrxO, （x = 4.16%） alloy is closest to the optimal ratio of 0,57. Besides, compared to the ZnO, the optical absorption does indicate a great improved absorption below the calculated band gap of the ZnO and an enhancement of the optical absorption in the whole solar spectral energy range.
基金supported by the projects of Chinese Academy of Sciences(Grant No.KZZD-EW-01-3)the National Basic Research Program of China(Grant No.2012CB825604)the National Natural Science Foundation of China(Grant Nos.41231065,41174137,41321003)
文摘Nighttime enhancements in ionospheric electron density at mid- and low-latitudes are investigated by using the critical frequency of the F2-1ayer （foF2） data measured from ionosonde stations at Okinawa （26.3°N, 127.8°E, Geomagnetic 15.3°N）, Yamagawa （31.2°N, 130.6°E, Geomagnetic 20.4°N）, Kokubunji （35.7°N, 139.5°E, Geomagnetic 25.5°N）, and Wakkanai （45.4°N, 141.7°E, Geomagnetic 35.4°N） in East Asia during several solar cycles. The results show that there are obvious seasonal and solar activity dependencies of the nighttime electron density enhancements. The enhancements are termed pre-midnight enhancement and post-midnight enhancement, according to the local time when the enhancement appeared. The former has a higher occurrence probability in summer months than in winter months. In contrast, the latter has a larger occurrence probability in winter months than in summer months. Moreover, the nighttime enhancements in electron density are more likely to occur at lower solar activity. These seasonal and solar activity variations of the nighttime enhancements in electron density can be explained in terms of the combined effects of downward plasma flux from the plasmasphere and the neutral winds.
