Hawking radiation of some black holes via the non-equilibrium Landauer transport model

Recently, Nation et al. confirmed that fluxes of Hawking radiation energy and entropy from a black hole can be regarded as a one-dimensional (1D) non-equilibrium Landauer transport process. Their work can be extended to background space-times with gauge potential. The result shows that the energy flux of charged particles, which is shown to be equal to the energy–momentum tensor flux, contains not only the contribution of thermal flux but also that of particle flux. It is found that the charge can also be transported by the 1D quantum channel. Moreover, the entropy production rate is also investigated, which is shown to be larger than the case without chemical potential.     

Numerical simulation for the temperature changing rule of the crude oil in a storage tank based on the wavelet finite element method

In order to study the temperature changing rule of the crude oil in the storage tank, the wavelet finite element method, the traditional finite element method and the test were used to carry out the numerical simulation. Firstly, the thermal wavelet finite element was put forward established based on thermal finite element theory and the wavelet theory. And the computational model and three boundary conditions were established. And then the temperature changing rule of the crude oil in the storage tank in 24 h for three boundary conditions was obtained by using three methods, and the results showed that the wavelet finite element method had advantages in the numerical analysis of the temperature changing rule of the crude oil in the storage. And then the temperature distribution rule of the crude oil in the storage tank under different conditions in 5 h was obtained. And the temperature changing mechanism of the crude oil was summarized finally.     

Interpenetrating Network Hydrogels based on Nanostructured Conductive Polymers for Flexible Supercapacitor

Flexible conductive polymer hydrogels are unique material that synergize the features of conductive polymers and hydrogels. They are excellent candidates for the flexible supercapacitor electrodes. In this paper, flexible conductive polymer hydrogels were prepared with poly(vinyl alcohol) as soft skeleton through cyclic freezing-thawing method. Firstly, phytic acid-doped polyaniline with crosslinked network was prepared using phytic acid as the dopant and crosslinking agents. Hydrogels with interpenetrating binary network nanostructure were then formed by freezing-thawing method. The interpenetrating binary network structure endowed the hydrogel reliable mechanical properties with decent flexibility and compressive strength of 3.64 MPa. More importantly, this unique structure enable them to maintain highly specific capacitance (314 F/g at the current density of 0.5 A/g).     

A compact and low-loss polarization splitter based on dual-core photonic crystal fiber

The characteristics of a novel dual-core photonic crystal fiber are investigated. In the center of photonic crystal fiber, an energy transmission channel is introduced. The optimized photonic crystal fiber can be used for polarization splitter, which has a short length and low loss.     

Exotic ferromagnetism in the two-dimensional quantum material C<Subscript>3</Subscript>N

The search for and study of exotic quantum states in novel low-dimensional quantum materials have triggered extensive research in recent years. Here, we systematically study the electronic and magnetic structures in the newly discovered two-dimensional quantum material C₃N within the framework of density functional theory. The calculations demonstrate that C₃N is an indirect-band semiconductor with an energy gap of 0.38 eV, which is in good agreement with experimental observations. Interestingly, we find van Hove singularities located at energies near the Fermi level, which is half that of graphene. Thus, the Fermi energy easily approaches that of the singularities, driving the system to ferromagnetism, under charge carrier injection, such as electric field gating or hydrogen doping. These findings not only demonstrate that the emergence of magnetism stems from the itinerant electron mechanism rather than the effects of local magnetic impurities, but also open a new avenue to designing field-effect transistor devices for possible realization of an insulator–ferromagnet transition by tuning an external electric field.