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Many studies have shown that straw return to the field can promote the production of photosynthetic material for crops, and thus increase crop yields. Due to the different effects of straw return to the field in different areas, there are fewer studies on the photosynthetic characteristics and yield of rice after straw return to the field in Northeast soda saline–alkali rice area, and it is not clear whether straw return reduces the amount of nitrogen fertilizer used in the area. Using the local large-scale cultivar Baijing 1 as the material, we studied the effects of straw return with nitrogen fertilizer (0, 90, 180, 270 and 360 kg ha−1) on the photosynthetic characteristics and seed yield of rice in saline–sodic areas through a 2 years field trial. The results of this experiment showed that rice yield was highly significantly and positively correlated with canopy total photosynthetically active radiation (TIPAR), leaf area index (LAI), relative chlorophyll content (SPAD), net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), Rubisco activity and PSII maximum photochemical efficiency (Fv/Fm) but significantly and negatively correlated with intercellular CO2concentration (Ci). Compared with the treatment without straw return, straw return increased TIPAR, LAI, SPAD, Pn, gs, Trand yield of rice when N≥ 180 kg N ha−1. The rice yield was the highest when the nitrogen application rate was 270 kg ha−1. The yield of straw return treatment under this nitrogen fertilizer was 8.01 t ha−1, and the yield of no straw return treatment was 7.52 t ha−1(average 2 years). In addition, the results suggested that approximately 36–43% of chemical Nfertilizer reduction would not affect rice yield with straw addition. Our results suggest that straw return is a promising management practice in soda saline–alkali rice areas that can reduce the application of mineral nitrogen fertilizer without losing rice yield.

In an intense circularly polarized laser field, the excitation of the atoms shows a strong dependence on the orbital helicity. The resonant excitation starting from the ground state with $ m = - 1 $m=−1 occurs much more easily in the left-handed circularly polarized (LCP with $ m = + 1 $m=+1) pulse than in the right-handed circularly polarized (RCP with $ m = - 1 $m=−1) pulse. In this Letter, we numerically demonstrate that the orbital-helicity-dependent two-photon-resonant excitation leads to the photoelectron vortex pattern in the polarization plane being sensitive to the sequence of the two counter-rotating circularly polarized pulses in xenon, which enables the detection of the ring currents associated with different quantum states. These results also provide an effective way for controlling the rotational symmetry of the electron vortex.

To observe the efficacy and safety of different dosages of modified Zhibaidihuang decoction (MZBDD) on polycystic ovary syndrome (PCOS) hyperandrogenism (HA) patients.

A 17-DOF mathematical model for a high-speed vehicle under steady crosswinds is established, and the nonlinear wheel/rail contact geometry and interactive forces are considered. Most importantly, the wheel profiles due to wears with the increase of operating mileage are measured, which have been used to calculate the wheel/rail contact geometry and equivalent conicity. The motion differential equation of the vehicle system is set up, and a program is written to calculate the critical speed under the corresponding parameters considering the vehicle running on straight and curved tracks with crosswind blowing to outer/inner rail. The linearization of the nonlinear vehicle system is conducted, and the critical speed is determined according to the eigenvalues of the linearized system in the equilibrium position. The results demonstrate that the critical speed of the vehicle system is significantly influenced by crosswind. The critical speed increases as the crosswind velocity is increasing when the crosswind blows to inner rail on curves, while it decreases as the crosswind blows to outer rail. And the wears of the wheel profiles also greatly contribute to the hunting stability of the vehicle system due to the resulted high equivalent conicity of wheel/rail contact. The critical speed increases with the increase of curve radius and super-elevation. It is also known through calculations that the derailment safety of the vehicle on curved track is greatly affected by crosswinds.