Detecting the orientation of the Néel vector is a major research topic in antiferromagnetic spintronics. Here we recognize the intrinsic nonlinear Hall effect, which is independent of the relaxation ...time, as a prominent contribution to the time-reversal-odd second order conductivity and can be used to detect the reversal of the Néel vector. In contrast, the Berry-curvature-dipole-induced nonlinear Hall effect depends linearly on relaxation time and is time-reversal even. We study the intrinsic nonlinear Hall effect in an antiferromagnetic metal: tetragonal CuMnAs, and show that its nonlinear Hall conductivity can reach the order of mA/V^{2}. The dependence on the chemical potential of such nonlinear Hall conductivity can be qualitatively explained by a tilted massive Dirac model. Moreover, we demonstrate its strong temperature dependence and briefly discuss its competition with the second order Drude conductivity. Finally, a complete survey of magnetic point groups is presented, providing guidelines for finding more antiferromagnetic materials with the intrinsic nonlinear Hall effect.
With the development of information technology, various cloud music services are gradually emerging, which has fully changed and enriched people’s music life. How to propose the songs that consumers ...anticipate from the enormous song data is one of the key goals of the music recommendation system. This research aims to create a better music algorithm that incorporates user data for deep learning, a candidate matrix compression technique for suggestion improvement, accuracy, recall rate, and other metrics as evaluation criteria. In terms of recommendation methods, the music-music recommendation method based on predicting user behavior data and the recommendation method based on automatic tag generation are proposed. The music features obtained by audio processing are fully utilized, and the depth content information in music audio data is combined with other data for recommendation, which improves the tag quality and avoids the problem of low coverage. The results show that this model can extract the effective feature representation of songs in different classification criteria and achieve a good classification effect simultaneously.
We derive the field correction to the Berry curvature of Bloch electrons, which can be traced back to a positional shift due to the interband mixing induced by external electromagnetic fields. The ...resulting semiclassical dynamics is accurate to second order in the fields, in the same form as before, provided that the wave packet energy is derived up to the same order. As applications, we discuss the orbital magnetoelectric polarizability and predict nonlinear anomalous Hall effects.
In recent years, there has been a growing interest in changes in dynamic mechanical properties of mixed rubber during dynamic shear, yet the influence of vulcanized characteristics on the dynamic ...shear behavior of vulcanized rubber, particularly the effect of cross-linking density, has received little attention. This study focuses on styrene-butadiene rubber (SBR) and aims to investigate the impact of different cross-linking densities (
) on dynamic shear behavior using molecular dynamics (MD) simulations. The results reveal a remarkable Payne effect, where the storage modulus experiences a significant drop when the strain amplitude (γ
) exceeds 0.1, which can be attributed to the fracture of the polymer bond and the decrease in the molecular chain's flexibility. The influence of various
values mainly resides at the level of molecular aggregation in the system, where higher
values impede molecular chain motion and lead to an increase in the storage modulus of SBR. The MD simulation results are verified through comparisons with existing literature.
A quantitative understanding of physiological thermal responses is vital for forecasting species distributional shifts in response to climate change. Many studies have focused on metabolic rate as a ...global metric for analyzing the sublethal effects of changing environments on physiology. Thermal performance curves (TPCs) have been suggested as a viable analytical framework, but standard TPCs may not fully capture physiological responses, due in part to failure to consider the process of metabolic depression. We derived a model based on the nonlinear regression of biological temperature‐dependent rate processes and built a heart rate data set for 26 species of intertidal molluscs distributed from 33°S to ~40°N. We then calculated physiological thermal performance limits with continuous heating using T1/2H, the temperature at which heart rate is decreased to 50% of the maximal rate, as a more realistic measure of upper thermal limits. Results indicate that heat‐induced metabolic depression of cardiac performance is a common adaptive response that allows tolerance of harsh environments. Furthermore, our model accounted for the high inter‐individual variability in the shape of cardiac TPCs. We then used these TPCs to calculate physiological thermal safety margins (pTSM), the difference between the maximal operative temperature (95th percentile of field temperatures) and T1/2H of each individual. Using pTSMs, we developed a physiological species distribution model (pSDM) to forecast future geographic distributions. pSDM results indicate that climate‐induced species range shifts are potentially less severe than predicted by a simple correlative SDM. Species with metabolic depression below the optimum temperature will be more thermal resistant at their warm trailing edges. High intraspecific variability further suggests that models based on species‐level vulnerability to environmental change may be problematic. This multi‐scale, mechanistic understanding that incorporates metabolic depression and inter‐individual variability in thermal response enables better predictions about the relationship between thermal stress and species distributions.
This multi‐scale, mechanistic understanding that incorporates metabolic depression and inter‐individual variability in thermal response enables better predictions about the relationship between thermal stress and species distributions.
As an emerging product of the rapid development of science and technology in the era of big data, digital media art is the application of various technologies, such as computer processing and digital ...special effects in film and television animation creation. This paper firstly takes digital media art as the research base and discusses the path of advancing digital media art in film and television animation. Secondly, the Web 3D interaction technology in digital media art is applied to the model building and animation generation of film and television animation, and the human body movements are captured to get the form reconstruction to generate SMPL human model parameters. Finally, a three-factor repeated measurement experiment and ablation experiment verified the feasibility and effectiveness of applying digital media art to film and television animation. The results show that the interaction of
and
has a significant main effect on the total interaction time
and
(15,43.213) = 62.329. In the ablation experiment, the increase points are 1.98, 1.63, and 1.52, which are greater than 1.5 on average. The application of digital media art to film and television animation proposed in this paper verifies the scheme’s feasibility through the ablation experiment and the three-factor repetition test. It also lays the foundation for the international development of Chinese film and animation.
Magnesium alloys have received great attention as a new kind of biodegradable metallic implants. However, poor corrosion resistance limited its applications. In order to improve the corrosion ...resistance and bioactivity of magnesium alloys, hydroxyapatite containing coatings were grown on AZ31 magnesium alloy by microarc oxidation. The thickness, morphologies and component of the coatings were investigated by SEM, XRD and XPS. Further, the corrosion resistance and degradation rate were also investigated. The main crystal phases of the coatings were MgO and hydroxyapatite. The thickness of the coatings increased with increasing the NaOH concentration. The coating showed a porous structure, and volcano top-like pores could be observed when the NaOH concentration was higher than 0.2 mol/L. Compared with the AZ31 substrate, all the coatings showed to significantly improve the corrosion resistance and greatly reduce the degradation rate. Among all, the coated sample formed in 0.2 mol/L NaOH showed the best corrosion resistance and the lowest degradation rate. Furthermore, complete coatings performed higher bonding strength more than 50 MPa, which meets the requirement of an implant biomaterial. This study provides insight into the development of bioactive coatings on magnesium alloys for biomedical applications.
•Hydroxyapatite containing coatings were formed on the surface of magnesium alloys by micro-arc oxidation.•NaOH actually acted both on the formation of barrier film and on the formation of HA phase.•The MAO coatings could prompt the corrosion resistance and reduce the degradation rate of the magnesium substrate.•All the coatings showed bonding strength higher than 50 MPa, which meets the requirement of an implant biomaterial.
Crystal engineering of the nbo metal–organic framework (MOF) platform MOF‐505 with a custom‐designed azamacrocycle ligand (1,4,7,10‐tetrazazcyclododecane‐N,N′,N′′,N′′′‐tetra‐p‐methylbenzoic acid) ...leads to a high density of well‐oriented Lewis active sites within the cuboctahedral cage in MMCF‐2, Cu2(Cu‐tactmb)(H2O)3(NO3)2. This MOF demonstrates high catalytic activity for the chemical fixation of CO2 into cyclic carbonates at room temperature under 1 atm pressure.
High catalytic activity for chemical fixation of CO2 into cyclic carbonates under ambient conditions has been demonstrated in the metal–organic framework (MOF) MMCF‐2 (see picture; C gray, O red, N blue, Cu pale blue). This MOF features a high density of well‐oriented Lewis acid active sites within the cuboctahedral cage.
We develop a general theory of the layer circular photogalvanic effect (LCPGE) in quasi-two-dimensional chiral bilayers, which refers to the appearance of a polarization-dependent, out-of-plane ...static dipole moment induced by circularly polarized light. We elucidate the geometric origin of the LCPGE as two types of interlayer coordinate shift weighted by the quantum metric tensor and the Berry curvature, respectively. As a concrete example, we calculate the LCPGE in twisted bilayer graphene, and find that it exhibits a resonance peak whose frequency can be tuned from visible to infrared as the twisting angle varies. The LCPGE thus provides a promising route toward frequency-sensitive, circularly polarized light detection, particularly in the infrared range.
PDF
