Two-step self-assembly between polyaniline and graphene oxide leads to a porous composite with high uniformity and excellent rate performance.

We study, by means of exact-diagonalization techniques, the ground state of a few-fermion system with strong short-range repulsive interactions trapped by a harmonic potential in one spatial dimension. Even when the ground-state density profile displays, at strong coupling, very well pronounced Wigner oscillations with a 4k F periodicity, the pair-correlation function does not show any signature of Wigner-molecule-type correlations. For the sake of comparison, we present also numerical results for few-electron systems with Coulomb interactions, demonstrating that their ground state at strong coupling is, on the contrary, a Wigner molecule.

Permafrost extends 40% of the Qinghai-Tibet Plateau (QTP), a region which contains the headwaters of numerous major rivers in Asia. As an aquiclude, permafrost substantially controls surface runoff and its hydraulic connection with groundwater. The freeze–thaw cycle in the active layer significantly impacts soil water movement direction, velocity, storage capacity, and hydraulic conductivity. Under the accelerating warming on the QTP, permafrost degradation is drastically altering regional and even continental hydrological regimes, attracting the attention of hydrologists, climatologists, ecologists, engineers, and decision-makers. A systematic review of permafrost hydrological processes and modeling on the QTP is still lacking, however, leaving a number of knowledge gaps. In this review, we summarize the current understanding of permafrost hydrological processes and applications of some permafrost hydrological models of varying complexity at different scales on the QTP. We then discuss the current challenges and future opportunities, including observations and data, the understanding of processes, and model realism. The goal of this review is to provide a clear picture of where we are now and to describe future challenges and opportunities. We concluded that more efforts are needed to conduct long-term field measurements, employ more advanced observation technologies, and develop flexible and modular models to deepen our understanding of permafrost hydrological processes and to improve our ability to predict the future responses of permafrost hydrology to climate changes.

The research and development of transition metal oxides based electrocatalysts with high activity and stability for both oxygen evolution reaction and hydrogen evolution reaction via a facile design strategy is of critical importance. Herein, we fulfill both significant oxygen evolution reaction and hydrogen evolution reaction improvement in activity by hierarchically nanostructured Ce-MnCo 2 O 4 prepared by an oxalate coprecipitation method and a followed calcination process. X-ray photoelectron spectroscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopy mappings analysis show that the hierarchically nanostructured Ce-MnCo 2 O 4 -3% sample is homogeneously modified by 1.49 wt % Ce with increased Co 3+ species. We suspect that the introduction of suitable Ce content into MnCo 2 O 4 facilitates the oxygen transfer and the formation of Co 3+ species, and modifies the local chemical binding, resulting in active performance for oxygen evolution reaction (390 mV at 10 mA•cm −2 and a Tafel slope of 125 mV•dec −1 ) in 1.0 M KOH solution. In addition, the Ce-MnCo 2 O 4 -3% sample also exhibits hydrogen evolution activity with overpotential of 389 mV at 10 mA•cm −2 and a Tafel slope of 96 mV• dec −1 , and relatively good long-time stability for 12 h.

Active video games (AVGs) refer to video games that incorporate body movement into video game playing (Baranowski, Buday, Thompson, & Baranowski, 2008; Mears & Hansen, 2009). AVGs and physical activity (PA) have attracted academic interest and have been explored since 2000. In such studies, the major focus has been on PA, energy expenditure, body composition, self-efficacy, social esteem, physical fitness, cognitive learning, social skills and sedentary behaviour in children (Barnett, Cerin, & Baranowski, 2011;

Track nonlinear energy sinks (track NESs) have been shown to be an effective and applicable strategy to mitigate structural response in recent years. However, previous studies on track NESs has mainly focused on demonstrating the benefits of track NESs through numerical simulations and experiments, with relatively little attention paid to the analytical understanding of the unique dynamics of track NESs. This study analyzes the responses of a track NES when subjected to impulsive and harmonic excitations by the harmonic balance method. Special attention is given to the cause and effect of the peaking behavior that is a prominent characteristic of the track NES's restoring forcedisplacement relationship. Analytical results reveal that the special energy-frequency characteristics of track NESs can be, at times, utilized to enhance the energy robustness that is absent in the conventional cubic NESs. Based on the analytical response expression, an equivalent linearization method (ELM) for the track NESs is developed for stochastic analysis. This ELM is numerically validated on the systems with strong nonlinearities. Stochastic optimization built on the ELM is performed to obtain design parameters of the track NES that can lead to minimum response variances of the primary structure. In particular, the proposed optimization procedure can be applied to seismic optimum design in which the seismic excitations are modeled as filtered whitenoise ground motions. The analytical techniques provided in this study lay the groundwork for the practical implementation of track NESs as a robust and effective control strategy for engineering structures. K E Y W O R D Sharmonic balance method, harmonic excitation, impulsive excitation, peaking behavior, stochastic optimization, track nonlinear energy sink

Citation: J Wang et al. "Parameters derived from the SDO/HMI vector magnetic field data: potential to improve machine-learning-based solar flare prediction models. AbstractIt is well established that solar flares and coronal mass ejections (CMEs) are powered by the free magnetic energy stored in volumetric electric currents in the corona, predominantly in active regions (ARs). Much effort has been made to search for eruption-related signatures from magnetic field observed mostly in the photosphere; and the signatures are further employed for predicting flares and CMEs. The parameters in the Space-weather HMI Active Region Patches (SHARP) data from the Solar Dynamics Observatory/HMI observation of vector magnetic field are designed and generated for this purpose. In this paper, we report research done on modification of these SHARP parameters with an attempt to improve flare prediction. The newly modified parameters are weighed heavily by magnetic polarity inversion lines (PIL) with high magnetic gradient, as suggested by Schrijver, by multiplying the parameters with a PIL mask. We demonstrate that the number of the parameters that can well discriminate erupted and nonerupted ARs increases significantly by a factor of two, in comparison with the original parameters. This improvement suggests that the high-gradient PILs are tightly related with solar eruption that agrees with previous studies. This also provides new data that possess potential to improve the machine-learningbased solar flare prediction models.

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