[en] A new method to measure the target velocity in laser plasma propulsion is proposed. By this method, the target velocity can be directly measured. The target thickness and the probe beam have no effects on measurement results. Compared with theoretical result, the error of experimental result is less than 2%. Furthermore, using this method, target momentum generation in laser-ablation water under different ambient temperatures is measured. Results show that the target momentum increases as the temperature decreases. (authors)

[en] The angular distribution and pressure force of droplets ejected from liquid water and glycerol ablated by nanosecond laser pulses are investigated under different viscosities in laser plasma propulsion. It is shown that with increasing viscosity, the distribution angles present a decrease tendency for two liquids, and the angular distribution of glycerol is smaller than that of water. A smaller distribution leads to a higher pressure force generation. The results indicate that ablation can be controlled by varying the viscosity of liquid propellant in laser plasma propulsion

[en] Highlights: • Estimate the impact of oil price uncertainty on corporate leverage and find a U-shaped relationship. • Identify the economics mechanisms through which oil price uncertainty affects corporate leverage. • Gauge the effects of ownership and marketization on the oil price uncertainty-leverage nexus. • Evaluate the impact of the market-oriented refined oil pricing reform on corporate leverage. • Evaluate the impact of the retail refined oil pricing market-oriented reform on corporate leverage. In view of the dramatic fluctuation of international oil price over the past decade, oil price uncertainty has aroused widespread concern of academia and policymakers. This paper firstly studies how oil price uncertainty affects corporate leverage, using the financial statement data of Chinese listed companies from 2007 to 2019. The results show that the relationship between oil price uncertainty and corporate leverage is nonlinear, and displays a U shape. Short-term debt financing is more strongly affected. Further analysis indicates that oil price uncertainty could reduce corporate leverage through increasing trade credit and heightening financial distress risk. In addition, this paper finds that the adverse effects of oil price uncertainty on state-owned enterprises or enterprises located in a region of high marketization are more pronounced. Finally, the findings demonstrate that with the advance of refined oil pricing market-oriented reform, the impact of oil price uncertainty on corporate leverage has been enhanced.

[en] Systemic measurements show that there is no 3D to 2D crossover in the reduction of the superconducting transition temperature T_c in Nb thin films. This result is consistent with all previous measurements while it is contrary to the prevailing understanding based on the interplay between proximity, localization, and lifetime broadening. Our study indicates that the decrease of T_c can be interpreted by the combined effects of electron-phonon coupling parameter λ and the defect scattering rate ρ_w, being uniquely determined by their ratio λ/ρ_w. Other factors such as film thickness and irradiation do not produce additional effects beyond these two parameters. (authors)