Magnetic properties of spin-1/2 Fermi gases with ferromagnetic interaction

We investigate the magnetic properties of spin-$1/2$ charged Fermi gases with ferromagnetic coupling via mean-field theory, and find the interplay among the paramagnetism, diamagnetism and ferromagnetism. Paramagnetism and diamagnetism compete with each other. When increasing the ferromagnetic coupling the spontaneous magnetization occurs in a weak magnetic field. The critical ferromagnetic coupling constant of the paramagnetic phase to ferromagnetic phase transition increases linearly with the temperature. Both the paramagnetism and diamagnetism increase when the magnetic field increases. It reveals the magnetization density $\bar M$ increases firstly as the temperature increases, and then reaches a maximum. Finally the magnetization density $\bar M$ decreases smoothly in the high temperature region. The domed shape of the magnetization density $\bar M$ variation is different from the behavior of Bose gas with ferromagnetic coupling. We also find the curve of susceptibility follows the Curie-Weiss law, and for a given temperature the susceptibility is directly proportional to the Land\'{e} factor.Comment: 7 pages, 7 figure

Green finance pilot reform and corporate green innovation

This study investigates the impact of the green finance pilot reform on corporate green innovation using the formation of the China Green Finance Pilot Reform in 2017 as a quasi-natural experiment. It shows that the green finance pilot reform increases corporate green innovation. Furthermore, by highlighting the differences between green enterprises and heavily polluting enterprises, it also shows that the positive relationship between the green finance pilot reform and corporate green innovation is more pronounced in green enterprises than in heavily polluting enterprises. The mechanism analysis shows that the green finance pilot reform mainly affects corporate green innovation by easing financing constraints and reducing financing costs. The heterogeneity analysis indicates that the positive relationship between the green finance pilot reform and corporate green innovation is more pronounced in non-state-owned enterprises and large-scale enterprises. As a result, the effect of the green finance pilot reform on corporate green innovation gives rise to certain green innovation incentives. It is thus necessary to optimise the external corporate governance environment by promoting the green finance pilot reform and further offers practical implications for corporate green innovation decision-making

Magnetic field induced incommensurate resonance in cuprate superconductors

The influence of a uniform external magnetic field on the dynamical spin response of cuprate superconductors in the superconducting state is studied based on the kinetic energy driven superconducting mechanism. It is shown that the magnetic scattering around low and intermediate energies is dramatically changed with a modest external magnetic field. With increasing the external magnetic field, although the incommensurate magnetic scattering from both low and high energies is rather robust, the commensurate magnetic resonance scattering peak is broadened. The part of the spin excitation dispersion seems to be an hourglass-like dispersion, which breaks down at the heavily low energy regime. The theory also predicts that the commensurate resonance scattering at zero external magnetic field is induced into the incommensurate resonance scattering by applying an external magnetic field large enough.Comment: 7 pages, 4 figures, typos corrected and updated references, accepted for publication in Journal of Magnetism and Magnetic Material

Deep high-temperature hydrothermal circulation in a detachment faulting system on the ultra-slow spreading ridge

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Tao, C., Seyfried, W. E., Jr., Lowell, R. P., Liu, Y., Liang, J., Guo, Z., Ding, K., Zhang, H., Liu, J., Qiu, L., Egorov, I., Liao, S., Zhao, M., Zhou, J., Deng, X., Li, H., Wang, H., Cai, W., Zhang, G., Zhou, H., Lin, J., & Li, W. Deep high-temperature hydrothermal circulation in a detachment faulting system on the ultra-slow spreading ridge. Nature Communications, 11(1), (2020): 1300, doi:10.1038/s41467-020-15062-w.Coupled magmatic and tectonic activity plays an important role in high-temperature hydrothermal circulation at mid-ocean ridges. The circulation patterns for such systems have been elucidated by microearthquakes and geochemical data over a broad spectrum of spreading rates, but such data have not been generally available for ultra-slow spreading ridges. Here we report new geophysical and fluid geochemical data for high-temperature active hydrothermal venting at Dragon Horn area (49.7°E) on the Southwest Indian Ridge. Twin detachment faults penetrating to the depth of 13 ± 2 km below the seafloor were identified based on the microearthquakes. The geochemical composition of the hydrothermal fluids suggests a long reaction path involving both mafic and ultramafic lithologies. Combined with numerical simulations, our results demonstrate that these hydrothermal fluids could circulate ~ 6 km deeper than the Moho boundary and to much greater depths than those at Trans-Atlantic Geotraverse and Logachev-1 hydrothermal fields on the Mid-Atlantic Ridge.This work was supported by National Key R&D Program of China under contract no. 2018YFC0309901, 2017YFC0306603, 2017YFC0306803, and 2017YFC0306203, COMRA Major Project under contract No. DY135-S1-01-01 and No. DY135-S1-01-06

Doping and energy dependent microwave conductivity of kinetic energy driven superconductors with extended impurities

Within the framework of the kinetic energy driven superconducting mechanism, the effect of the extended impurity scatterers on the quasiparticle transport of cuprate superconductors in the superconducting state is studied based on the nodal approximation of the quasiparticle excitations and scattering processes. It is shown that there is a cusplike shape of the energy dependent microwave conductivity spectrum. At low temperatures, the microwave conductivity increases linearly with increasing temperatures, and reaches a maximum at intermediate temperature, then decreases with increasing temperatures at high temperatures. In contrast with the dome shape of the doping dependent superconducting gap parameter, the minimum microwave conductivity occurs around the optimal doping, and then increases in both underdoped and overdoped regimes.Comment: 9 pages, 3 figure

Dynamic Reliability Analysis of Layered Slope Considering Soil Spatial Variability Subjected to Mainshock–Aftershock Sequence

The slope instability brought on by earthquakes frequently results in significant property damage and casualties. At present, the research on displacement response of a slope under earthquake has mainly emphasized the action of the mainshock, without accounting for the impact of an aftershock, and the spatial variability of material parameters is often neglected. The spatial variability of parameters is fully accounted for in this paper, and dynamic reliability of permanent displacement (DP) of a slope produced by the mainshock–aftershock sequence (MAS) is studied. A slope reliability analysis method is proposed based on the Newmark displacement method and the generalized probability density evolution method (GPDEM) to quantify the effect of the spatial variability of materials parameters on dynamic reliability. Firstly, the parameter random field is generated based on the spectral representation method, and the randomly generated parameters are assigned to the finite element model (FEM). In addition, the random simulation method of MAS considering the correlation between aftershock and mainshock is adopted based on the Copula function to generate the MAS. Then, the DP of slopes caused by the MAS considering the spatial variability is calculated based on the Newmark method. The impacts of the coefficient of variation (COV) and aftershock on the DP of slope is analyzed by means of mean values. Finally, the effect of COV and aftershock on the reliability of DP is explained from a probabilistic point of view based on the GPDEM. The results revealed that with the increase in the COV, the mean of the DP of the slope shows a trend of increasing gradually. The DP of slope is more sensitive to the coefficient of variation of friction angle (COVF). The mean DP of the slope induced by the MAS is larger compared to the single mainshock, and the PGA has a significant impact on the DP

An integrated approach to developing self-adaptive software in open environments

One of the main challenges of developing self-adaptive systems in open environment comes from uncertain self-adaptation requirements due to the unpredictability of environment changes and its co-existence with well-defined self-adaptation requirements in self-adaptive systems. This paper presents an integrated approach that combines off-line and on-line self-adaptation together in a unified technical framework to support the development and running of such systems. We consider self-adaptive system as a multi-agent organization and propose a novel dynamic binding self-adaptation mechanism inspired from organization metaphors to specify and analyze self-adaptation. A description language, SADL, is designed to program well-defined self-adaptation logic at design-time and implement off-line self-adaptation. In order to deal with uncertain self-adaptation, a reinforcement learning method is incorporated with the dynamic binding mechanism, which enables software agents to make decisions on self-adaptation at run-time and implement on-line self-adaptation. Our approach provides a unified frame-work to accommodate off-line and on-line approaches and a general-purpose methodology to develop complex self-adaptive systems in a systematic way. A supported platform called SADE+ is developed and a case is studied to illustrate the proposed approach

Designing “Core–Shell” Insoluble‐SiW11Fe@δ‐Bi2O3 Z‐Scheme Heterojunction for Photo‐Driven Nitrogen Reduction Reaction and Evaluating the Impact of Oxygen toward Nitrogen Reduction

Abstract Photo‐driven nitrogen fixation is regarded as a promising sustainable strategy to generate low‐concentration NH3/NH4+. Insoluble SiW11Fe@δ‐Bi2O3 with “core–shell” structure and Z‐scheme featured heterojunction is constructed under solvothermal conditions. Chemisorption of nitrogen improves significantly due to increased oxygen vacancies on δ‐Bi2O3 as induced by insoluble SiW11Fe salt. Z‐scheme heterojunction is suggested according to energy diagram analyses and electron paramagnetic resonance spin‐trapping experiments, which can be well correlated to enhanced transient photocurrent and catalytic efficacy. [Ru(bpy)3]2+ counter ion in the composite acts as a photosensitizer, leading to improved light harvesting. These merits account for superior performance of Ru2.5SiW11Fe@δ‐Bi2O3. NH3/NH4+ production rate of 121 µmol gcat−1 h−1 is achieved under simulated sunlight irradiation in nitrogen atmosphere, but reduces on switching to air. The impact of oxygen over nitrogen reduction is investigated, and productions of both NH3/NH4+ and H2O2 are evaluated when using gas mixture feedstock with different V(N2):V(O2) ratios. The performance of nitrogen reduction depends mainly on its volume ratio in mixture feedstock, in addition to reduction capability of photocatalyst. By reducing the latter one appropriately, nitrogen reduction would be slightly favored when using air as feedstock