Experimental confirmation of driving pressure boosting and smoothing for hybrid-drive inertial fusion at the 100-kJ laser facility.

In laser-driven inertial confinement fusion, driving pressure boosting and smoothing are major challenges. A proposed hybrid-drive (HD) scheme can offer such ideal HD pressure performing stable implosion and nonstagnation ignition. Here we report that in the hemispherical and planar ablator targets installed in the semicylindrical hohlraum scaled down from the spherical hohlraum of the designed ignition target, under indirect-drive (ID) laser energies of ~43-50 kJ, the peak radiation temperature of 200 ± 6 eV is achieved. And using only direct-drive (DD) laser energies of 3.6-4.0 kJ at an intensity of 1.8 × 1015 W/cm2, in the hemispherical and planar targets the boosted HD pressures reach 3.8-4.0 and 3.5-3.6 times the radiation ablation pressure respectively. In all the above experiments, significant HD pressure smoothing and the important phenomenon of how a symmetric strong HD shock suppresses the asymmetric ID shock pre-compressed fuel are demonstrated. The backscattering and hot-electron energy fractions both of which are about one-third of that in the DD scheme are also measured.

Platelet membrane-coated alterbrassicene A nanoparticle inhibits calcification of the aortic valve by suppressing phosphorylation P65 NF-κB.

Rationale: Calcific aortic valve disease (CAVD) is a leading cause of cardiovascular mortality and morbidity with increasing prevalence and incidence. The pathobiology of CAVD involves valvular fibrocalcification, and osteogenic and fibrogenic activities are elevated in aortic valve interstitial cells (VICs) from diseased valves. It has been demonstrated that activated NF-κB pathway was present in the early stage of CAVD process. There is currently no effective clinical drugs targeting NF-κB pathway for CAVD treatment. Therefore, it is of great clinical significance to seek effective treatments for valve calcification. Methods: In this study, we established immortal human valve interstitial cells (im-hVICs) with pGMLV-SV40T-puro lentivirus. Alizarin red staining and western blotting were performed to evaluate the calcification of immortal VICs supplemented with different compounds. The natural fusicoccane diterpenoid alterbrassicene A (ABA) was found to have potential therapeutic functions. Ribonucleic acid sequencing was used to identify the potential target of ABA. Platelet membrane-coated nanoparticle of ABA (PNP-ABA) was fabricated and the IBIDI pump was used to evaluate the adhesion ability of PNP-ABA. Murine wire-induced aortic valve stenosis model was conducted for in vivo study of PNP-ABA. Results: The natural fusicoccane diterpenoid ABA was found to significantly reduce the calcification of human VICs during osteogenic induction via inhibiting the phosphorylation P65. Runt-related transcription factor 2 (Runx2) and bone morphogenetic protein-2 (BMP2) were down regulated with the treatment of ABA in human VICs. Additionally, molecular docking results revealed that ABA bound to RelA (P65) protein. Phosphorylation of P65 (Ser536) was alleviated by ABA treatment, as well as the nuclear translocation of P65 during osteogenic induction in human VICs. Alizarin red staining showed that ABA inhibited osteogenic differentiation of VICs in a dose-dependent manner. PNP-ABA attenuated aortic valve calcification in murine wire-induced aortic valve stenosis model in vivo. Conclusions: The establishment of im-hVICs provides a convenient cell line for the study of CAVD. Moreover, our current research highlights a novel natural compound, ABA, as a promising candidate to prevent the progression of CAVD.

Assessment of the electron-proton energy relaxation rates extracted from molecular dynamics simulations in weakly-coupled hydrogen plasmas.

Electron-proton energy relaxation rates are assessed using molecular dynamics (MD) simulations in weakly-coupled hydrogen plasmas. To this end, we use various approaches to extract the energy relaxation rate from MD-simulated temperatures, and we find that existing extracting approaches may yield results with a sizable discrepancy larger than the variance between analytical models, which is further verified by well-known case studies. Present results show that two of the extracting approaches can produce identical results, which is attributed to a proper treatment of relaxation evolution. To discriminate the use of various methods, an empirical criterion with respect to initial plasma temperatures is proposed, which can self-consistently explain the cases considered. In addition, for a transient electron-proton plasma, we show that it is possible to extrapolate the Coulomb logarithm from that derived by initial plasma parameters in a single MD calculation, which is reasonably consistent with previous MD data. Our results are helpful to obtain accurate MD-based energy relaxation rates.

Stochastic radiative transfer in random media. II. Coupling of radiation to material.

We study the mechanism of the impact of random media on the stochastic radiation transport based on a one-dimensional (1D) planar model. To this end, we use a random sampling of mixtures combined with a deterministic solution of the time-dependent radiation transport equation coupled to a material temperature equation. Compared to purely absorbing cases [C.-Z. Gao et al., Phys. Rev. E 102, 022111 (2020)10.1103/PhysRevE.102.022111], we find that material temperatures can significantly suppress the impact of mixing distribution and size, which is understood from the analysis of energy transport channels. By developing a steady-state stochastic transport model, it is found that the mechanism of transmission of radiation is distance dependent, which is closely related to the mean free path of photons l_{p}. Furthermore, we suggest that it is the relationship between l_{p} and L (the width of random medium) that determines the impact of random media on the stochastic radiation transport, which is further corroborated by additional simulations. Most importantly, combining the proposed simple relationship and 1D simulations, we resolve the existing disputable issue of the impact of random media in previous multidimensional works, showing that multidimensional results are essentially consistent and the observed weak or remarkable impact of random media is mainly due to the distinctly different relationship between l_{p} and L. Our results may have practical implications in relevant experiments of stochastic radiative transfer.

Secondary instability of the spike-bubble structures induced by nonlinear Rayleigh-Taylor instability with a diffuse interface.

Laminar-turbulent transition in Rayleigh-Taylor (RT) flows usually starts with infinitesimal perturbations, which evolve into the spike-bubble structures in the nonlinear saturation phase. It is well accepted that the emergence and rapid amplification of the small-scale perturbations are attributed to the Kelvin-Helmholtz-type secondary instability due to the high velocity shears induced by the stretch of the spike-bubble structures, however, there has been no quantitative description on such a secondary instability in literature. Moreover, the instability mechanism may not be that simple, because the acceleration or the "rising bubble" effect could also play a role. Therefore, based on the two-dimensional diffuse-interface RT nonlinear flows, the present paper employs the Arnoldi iteration and generalized Rayleigh quotient iteration methods to provide a quantitative study on the secondary instability. Both sinuous and varicose instability modes with high growth rates are observed, all of which are confirmed to be attributed to both the Rayleigh-Taylor and Kelvin-Helmholtz regimes. The former regime dominates the early-time instability due to the "rising bubble" effect, whereas the latter regime becomes more significant as time advances. Being similar to the primary RT instability [Yu et al., Phys. Rev. E 97, 013102 (2018)2470-004510.1103/PhysRevE.97.013102, Dong et al., Phys. Rev. E 99, 013109 (2019)2470-004510.1103/PhysRevE.99.013109, Fan and Dong, Phys. Rev. E 101, 063103 (2020)2470-004510.1103/PhysRevE.101.063103], the diffuse interface also leads to a multiplicity of the secondary instability modes and higher-order modes are found to exhibit more local extremes than the lower-order ones. Direct numerical simulations are carried out, which confirm the linear growth of the secondary instability modes with infinitesimal amplitudes and show their evolution to the turbulent-mixing state.

Stochastic radiative transfer in random media: Pure absorbing cases.

We study stochastic radiation transport through random media in one dimension, in particular for pure absorbing cases. The statistical model to calculate the ensemble-averaged transmission for a binary random mixture is derived based on the cumulative probability density function (PDF) of optical depth, which is numerically simulated for both Markovian and non-Markovian mixtures by Monte Carlo calculations. We present systematic results about the influence of mixtures' stochasticity on the radiation transport. It is found that mixing statistics affects the ensemble-averaged intensities mainly due to the distribution of cumulative PDF at small optical depths, which explains well why the ensemble-averaged transmission is observed to be sensitive to chord length distribution and its variances. The effect of the particle size is substantial when the mixtures' correlation length is comparable to the mean free path of photons, which imprints a moderately broad transition region into the cumulative PDF. With the mixing probability increasing, the intensity decreases nearly exponentially, from which the mixing zone length can be approximately estimated. The impact of mixed configuration is also discussed, which is in line with previous results.

Multiple eigenmodes of the Rayleigh-Taylor instability observed for a fluid interface with smoothly varying density. III. Excitation and nonlinear evolution.

A compressible Rayleigh-Taylor (RT) unstable flow with a diffuse interface where the density varies smoothly supports a multiplicity of unstable eigenmodes that grow exponentially in time. This paper studies two relevant problems in a two-dimensional (2-D) RT flow by use of multimode decomposition. The first one is the excitation of these modes by arbitrarily introduced infinitesimal perturbations. The initial amplitude of each mode is calculated by projecting the introduced perturbation into the eigenvector space, and the obtained initial amplitude can be used to predict the linear evolution of the perturbation accurately, as is confirmed by direct numerical simulations. If the initial perturbation includes pressure or velocity components, then in addition to the growth of the RT mode, a strong acoustic wave package would be radiated to the heavy fluid, whereas a mild acoustic wave package would be radiated to the light fluid. As the second problem, in order to reveal the interaction feature of the unstable normal modes in the nonlinear phase, we perform the multimode decomposition based on the instantaneous perturbation field under the Fourier transformation in the direction tangential to the interface. For the current case studies, the emergence of the bubble-spike structure is mainly attributed to the nonlinear amplification of the odd modes decomposed from the fundamental disturbances. As time advances to the nonlinear phase, the projection to the low-order normal modes possesses less portion of the total energy due to the complexity of the multipeak perturbation profiles.

Multiple eigenmodes of the Rayleigh-Taylor instability observed for a fluid interface with smoothly varying density. II. Asymptotic solution and its interpretation.

It was observed in the first part of this work [C. X. Yu et al., Phys. Rev. E 97, 013102 (2018)2470-004510.1103/PhysRevE.97.013102] that a Rayleigh-Taylor flow with a smoothly varying density at the interface permits a multiplicity of solutions for instability modes. Based on numerical solutions of the eigenvalue problem, a fitting expression for the multiple eigenmodes of the Rayleigh-Taylor instability was provided. However, the fitted curves showed poor agreement with the numerical solutions when the Atwood number was relatively high. This paper develops an asymptotic solution based on the Wentzel-Kramers-Brillouin approximation for high wave numbers in the direction tangential to the interface. The asymptotic solution of the eigenmode of each order can provide a fine prediction for moderate and high wave numbers as confirmed by a comparison with numerical solutions and, more importantly, the physical interpretation of the multiple-mode phenomenon is exhibited. We also show simpler expressions of the growth rates when the Atwood number approaches 0 or 1.