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

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.

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.

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.

The deep learning method of long short-term memory (LSTM) is applied to develop a model to predict the daily >2-MeV electron integral flux 1 day ahead at geostationary orbit. The inputs to the model include geomagnetic and solar wind parameters such as Kp, Ap, Dst, solar wind speed, magnetopause subsolar distance, and the value of >2-MeV electron integral flux itself over the previous five consecutive days. The model is trained on the data from the periods 1999-2007 and 2011-2016, and the efficiency of the model is tested on the 2008-2010 period. We experiment with different input combinations and find that when the model takes daily >2-MeV electron integral flux, daily averaged magnetopause subsolar distance, and daily summed Kp index as inputs, the prediction efficiencies for 2008, 2009, and 2010 are 0.833, 0.896, and 0.911, respectively. This value reaches 0.900 for 2008, when hourly >2-MeV electron integral flux, hourly magnetopause subsolar distance, and daily summed Kp index are taken as inputs, with training on the remaining data from 19 June 2003 to 13 April 2010. The prediction efficiencies of the persistence model and the 27-order autoregressive model for the same tested time period are 0.679 and 0.743, respectively. Therefore, the model developed based on the LSTM method can improve the prediction efficiency significantly for daily >2-MeV electron integral flux 1 day ahead at geostationary orbit.