Abstract: In proton radiography, degeneracy of electric and magnetic fields in deflecting the probe protons can prevent full interpretation of proton flux perturbations in the detection plane. In this paper, theoretical analyses and numerical simulations suggest that the contributions of the electric and magnetic fields can be separately obtained by analyzing the difference between the flux distributions of two discriminated proton energies in a single shot of proton radiography. To eliminate the influence of field evolution on the separation, a strategy is proposed in which slow field evolution is assumed or an approximate estimate of field growth is made. This could help achieve a clearer understanding of the radiographic process and allow further quantitative analysis.

Abstract: Micro-structured targets have been widely used in the interaction between ultra-intense laser and target, aiming at improving the electron accelerating efficiency. In this paper, we perform two-dimensional particle-in-cell (PIC) simulations to study the interaction of the ultra-intense laser pulse with the micro-structured foam-attached target (the foam is composed of low density bubbles and high density interfaces between the bubbles). It is found that at the beginning of the laser-plasma interaction, the fast electrons accelerated at the front surface of the foam freely propagate into the target and drive a return current of cold background electrons. These cold background electrons are restricted to propagate along the interfaces between the bubbles in the foam due to the self-generated large sheath field. As a result, small current filaments are generated in the foam, which then leads to the generation of randomly distributed megagauss magnetic field in the foam layer. This quasistatic magnetic field then acts as an energy-selective " magnetic barrier”: the low-energy electrons are reflected back into the laser acceleration region while the high-energy electrons can penetrate through it. If the reflected electrons enter into the laser field with proper phases, they can be further accelerated to higher energy through cooperative actions of the ultra-intense laser pulse and the sheath field generated due to plasma expansion at the target surface. Our simulation results show that many of the laser accelerated low-energy electrons can be reflected back and accelerated several times until they gain enough energy to penetrate through the magnetic barrier. This is termed the " multiple acceleration mechanism”. Due to this mechanism, the electron acceleration efficiency in the foam-coated target with a thickness of several microns is significantly enhanced in comparison with that in the plane target. This enhancement in the electron acceleration efficiency will be beneficial to many important applications such as the fast ignition. Additionally, foam-coated targets with different bubble radii and layer thickness are also studied, and it is found that the yield of the high energy electrons increases with the radius of bubble size more efficiently than with the bubble thickness. In order to understand the physics more clearly, a single particle model is developed to analyze the simulation results.

Abstract: Laser plasma instability is one of the difficulties that plague inertial confinement fusion. Broadband laser, as an effective tool for suppressing laser-plasma instabilities, has received a lot of attention in recent years. However, the nonlinear bursts of high-frequency instabilities, such as stimulated Raman scattering driven by broadband laser in the kinetic regime, make the suppression effect less than expected. In this study, a broadband laser model with intensity modulation is proposed. By choosing an appropriate intensity modulation envelope, it is possible to interrupt the amplification process of backscattered light in strong pulses, reduce the probability of high-intensity pulses inducing intense bursts, and drastically reduce the fraction of backscattered light and hot electron yield. Numerical simulations show that the intensity-modulated laser has a good ability to suppress stimulated Raman scattering. For a broadband laser with average power of 〈 inline-formula 〉 〈 tex-math id="M2" 〉 \begin{document}$ 1.0 \times {10}^{15}\;{\mathrm{W}}/{\mathrm{c}}{{\mathrm{m}}}^{2} $\end{document} 〈 /tex-math 〉 〈 alternatives 〉 〈 graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20231679_M2.jpg"/ 〉 〈 graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20231679_M2.png"/ 〉 〈 /alternatives 〉 〈 /inline-formula 〉 and a bandwidth of 0.6%, the reflectivity decreases by an order of magnitude and the fraction of hot electron energy above 20 keV decreases from 7.34% to 0.31% by using the intensity modulation technique. The above results confirm the feasibility of using the intensity-modulated broadband laser to suppress the high-frequency instability and are expected to provide a reference for designing the subsequent broadband laser-driven fusion experiments.

Abstract: Inhaled budesonide is a novel approach to prevent acute mountain sickness (AMS). However, its mechanism is not completely understood. We aimed to investigate the effects of budesonide and dexamethasone on renin–angiotensin–aldosterone system in AMS prevention. Materials and methods: Data were obtained from a randomised controlled trial including 138 participants. The participants were randomly assigned to receive budesonide, dexamethasone or placebo as prophylaxis before they travelled to 3450 m altitude from 400 m by car. Their plasma concentrations of renin, angiotensin-converting enzyme (ACE) and aldosterone were measured at both altitudes. Results: All parameters were comparable among the three groups at 400 m. After high-altitude exposure of 3450, renin in all groups increased significantly; the ACE, aldosterone concentrations, as well as the aldosterone/renin ratio, rose markedly in the dexamethasone and placebo groups but not in the budesonide group. Moreover, the aldosterone/renin ratio correlated closely with ACE concentration. Conclusions: Upon acute high-altitude exposure, budesonide, but not dexamethasone, blunted the response of aldosterone to renin elevation by suppressing angiotensin converting enzyme.

Abstract: In this paper, uniform TiO 2 nanowires (TiO 2 NWs) on reduced graphene oxide (RGO) nanosheets were successfully synthesized by a simple and low‐cost hydrothermal method. The high capacitance (202.5 F⋅g −1 at 1 A⋅g −1 ) and excellent cyclic stability (81.9% capacity retention after 5000 cycles) were achieved for TiO 2 NWs‐RGO nanocomposite as supercapacitor electrode. The excellent electrochemical performance is due to the synergistic effect of one‐dimensional TiO 2 NWs with chemical stability and RGO with excellent conductivity. Moreover, TiO 2 NWs can effectively avoid agglomeration, shorten the ion diffusion length and greatly facilitate the charge transfer both at the contact interfaces and within the electrode materials during the electrochemical process. A symmetric supercapacitor was successfully assembled using the TiO 2 NWs‐RGO nanocomposite. It possesses a remarkable performance with a specific capacitance of 45.7 F⋅g −1 , an energy density of 9.08 Wh⋅kg −1 at a power density of 598 W⋅kg −1 .

Abstract: When evaluating the plasma parameters in inertial confinement fusion, the flux-limited local Spitzer-Härm (S-H) model in radiation hydrodynamics simulations may be invalid when electron temperature gradient is too large. In other publications, the electron distribution function (EDF) could be explained by comparing the energy equipartition rate 〈inline-formula〉〈tex-math id="M7"〉\begin{document}$R_{\rm eq}=\dfrac{1}{2}m_{\rm e}v_{\rm te} ^2\nu_{\rm ee}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M7.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M7.png"/〉〈/alternatives〉〈/inline-formula〉 with the heating rate 〈inline-formula〉〈tex-math id="M8"〉\begin{document}$R_{\rm heat}=\dfrac{1}{2}m_{\rm e}v_{\rm os} ^2\nu_{\rm ei}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M8.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M8.png"/〉〈/alternatives〉〈/inline-formula〉. When the condition 〈inline-formula〉〈tex-math id="M9"〉\begin{document}$R_{\rm heat}\sim R_{\rm eq}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M9.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M9.png"/〉〈/alternatives〉〈/inline-formula〉 is satisfied, the EDF deviates from Maxwell equilibrium distribution, and is well fitted to the super-Gaussian distribution 〈inline-formula〉〈tex-math id="M10"〉\begin{document}$f({{ v}})=C_m{\rm e}^{-(v/v_m)^m}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M10.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M10.png"/〉〈/alternatives〉〈/inline-formula〉 with the index 〈i〉m 〈/i〉(〈inline-formula〉〈tex-math id="M11"〉\begin{document}$2〈m〈5$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M11.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M11.png"/〉〈/alternatives〉〈/inline-formula〉). The number of energetic electrons of the super-Gaussian distribution is less than that of the Maxwell distribution, which plays an important role in electron heat flux, especially for electrons of 3.7〈inline-formula〉〈tex-math id="M12"〉\begin{document}$v_{\rm te}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M12.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M12.png"/〉〈/alternatives〉〈/inline-formula〉. So electron heat flux of the super-Gaussian distribution is smaller than that of the Maxwell distribution. In this paper, EDF and electron heat flux in laser-produced Au plasma are simulated by using 1D3V PIC code (Ascent). It is found that in the coronal region, the laser intensity is larger, and the electron temperature is lower than the high-density region. So 〈inline-formula〉〈tex-math id="M13"〉\begin{document}$\alpha=Z(v_{\rm os}/v_{\rm te})^2〉1$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M13.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M13.png"/〉〈/alternatives〉〈/inline-formula〉, 〈inline-formula〉〈tex-math id="M14"〉\begin{document}$R_{\rm heat}〉R_{\rm eq}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M14.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M14.png"/〉〈/alternatives〉〈/inline-formula〉, the EDF is well fitted to super-Gaussian distribution, where the index 〈i〉m〈/i〉 is evaluated to be 3.34. In this region, the large electron temperature gradient leads to a small temperature scale length (〈inline-formula〉〈tex-math id="M15"〉\begin{document}$L_{\rm e}=T_{\rm e}/(\partial T_{\rm e}/\partial x)$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M15.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M15.png"/〉〈/alternatives〉〈/inline-formula〉), but the low e-e and e-i collision frequencies lead to a large electron mean-free-path (〈inline-formula〉〈tex-math id="M16"〉\begin{document}$\lambda_{\rm e}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M16.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M16.png"/〉〈/alternatives〉〈/inline-formula〉). So the Knudsen number 〈inline-formula〉〈tex-math id="M17"〉\begin{document}$\lambda_{\rm e}/L_{\rm e}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M17.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M17.png"/〉〈/alternatives〉〈/inline-formula〉 is evaluated to be 0.011, which is much larger than the critical value 〈inline-formula〉〈tex-math id="M18"〉\begin{document}$2\times10^{-3}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M18.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M18.png"/〉〈/alternatives〉〈/inline-formula〉 of the S-H model, flux-limited local S-H electron heat flux is invalid. As a result, the limited-flux S-H predicts too large an electron heat flux, which results in much higher electron temperature of radiation hydrodynamics simulation than that of SG experiments. This heat flux inhibition phenomenon in coronal region cannot be explained by the flux-limited local S-H model, and non-local electron heat flux should be considered. In the high density region, the laser intensity is weaker, and the electron temperature is higher, so 〈inline-formula〉〈tex-math id="M19"〉\begin{document}$\alpha=Z(v_{\rm os}/v_{\rm te})^2〈1$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M19.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M19.png"/〉〈/alternatives〉〈/inline-formula〉, 〈inline-formula〉〈tex-math id="M20"〉\begin{document}$R_{\rm heat}〈R_{\rm eq},$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M20.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M20.png"/〉〈/alternatives〉〈/inline-formula〉 but EDF is still well fitted to super-Gaussian distribution, where the index m is evaluated to be 2.93. In this region, 〈inline-formula〉〈tex-math id="M21"〉\begin{document}$L_{\rm e}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M21.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M21.png"/〉〈/alternatives〉〈/inline-formula〉 is larger, 〈inline-formula〉〈tex-math id="M22"〉\begin{document}$\lambda_{\rm e}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M22.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M22.png"/〉〈/alternatives〉〈/inline-formula〉 is smaller, so the Knudsen number is smaller, which is evaluated to be 〈inline-formula〉〈tex-math id="M23"〉\begin{document}$7.58\times10^{-4}〈2\times10^{-3}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M23.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M23.png"/〉〈/alternatives〉〈/inline-formula〉. As a result, The flux-limited local S-H electron heat flux is valid. However, the electron heat flux depends on the flux limiting factor (〈inline-formula〉〈tex-math id="M24"〉\begin{document}$f_{\rm e}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M24.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20191423_M24.png"/〉〈/alternatives〉〈/inline-formula〉) that varies with laser intensity and electron temperature.

Abstract: MoS 2 nanoflakes were prepared by exfoliating commercial MoS 2 powders with the assistance of ultrasound and graphene foam was synthesized by chemical vapor deposition using nickel foam as the template. MoS 2 ‐graphene hybrid nanosheets were developed through the combination of MoS 2 nanoflakes and graphene nanosheets by ultrasonic dispersion. The hybrid nanosheets were sprayed onto the ITO coated glass, which acts as an electrode for the simultaneously electrochemical determination of levodopa and uric acid. The MoS 2 ‐graphene hybrid nanosheets were characterized by scanning electron microscopy, X‐ray diffraction and Raman spectroscopy. The results show that the hybrid nanosheets are composed of MoS 2 and graphene with a sheet‐like morphology. The sensitivity of the electrode for levodopa and uric acid is 0.36 μA μM −1 and 0.39 μA μM −1 , respectively. The electrode also shows low limit of detection, good selectivity, reproducibility and stability. And it is potential for use in clinical research.