New class of 3D topological insulator in double perovskite

We predict a new class of three-dimensional topological insulators (TIs) in which the spin-orbit coupling (SOC) can more effectively generate a large band gap at $\Gamma$ point. The band gap of conventional TI such as Bi$_2$Se$_3$ is mainly limited by two factors, the strength of SOC and, from electronic structure perspective, the band gap when SOC is absent. While the former is an atomic property, we find that the latter can be minimized in a generic rock-salt lattice model in which a stable crossing of bands {\it at} the Fermi level along with band character inversion occurs for a range of parameters in the absence of SOC. Thus, large-gap TI's or TI's comprised of lighter elements can be expected. In fact, we find by performing first-principle calculations that the model applies to a class of double perovskites A$_2$BiXO$_6$ (A = Ca, Sr, Ba; X = Br, I) and the band gap is predicted up to 0.55 eV. Besides, more detailed calculations considering realistic surface structure indicate that the Dirac cones are robust against the presence of dangling bond at the boundary with a specific termination.Comment: submitted; title changed and new references added; see DOI for published versio

Fault Diagnosis of Car Engine by Using a Novel GA-Based Extension Recognition Method

Due to the passenger’s security, the recognized hidden faults in car engines are the most important work for a maintenance engineer, so they can regulate the engines to be safe and improve the reliability of automobile systems. In this paper, we will present a novel fault recognition method based on the genetic algorithm (GA) and the extension theory and also apply this method to the fault recognition of a practical car engine. The proposed recognition method has been tested on the Nissan Cefiro 2.0 engine and has also been compared to other traditional classification methods. Experimental results are of great effect regarding the hidden fault recognition of car engines, and the proposed method can also be applied to other industrial apparatus

Influence of Implementing Inquiry-based Instruction on Science Learning Motivation and Interest: A Perspective of Comparison

AbstractThe purpose of this study was to explore the influence of implementing inquiry-based instruction on science-learning motivation and interest. The participants included students from three high schools located north, west, and south of Taiwan.The results showed that after participating in the implementation of inquiry-based instruction, science learning motivation and interest were both increased. Among them, School A achieved the best learning effect. Significant variation was observed in terms of self-efficacy and performance goals with regard to learning motivation; considerable differences in learning interests were also seen with respect to attitude towards science, learning atmosphere, learning difficulties, and learning commitment

Biosorption of Pb (II) from aqueous solution by extracellular polymeric substances extracted from Klebsiella sp. J1: Adsorption behavior and mechanism assessment.

The adsorption performance and mechanism of extracellular polymeric substances (EPS) extracted from Klebsiella sp. J1 for soluble Pb (II) were investigated. The maximum biosorption capacity of EPS for Pb (II) was found to be 99.5 mg g(-1) at pH 6.0 and EPS concentration of 0.2 g/L. The data for adsorption process satisfactorily fitted to both Langmuir isotherm and pseudo-second order kinetic model. The mean free energy E and activation energy Ea were determined at 8.22- 8.98 kJ mol(-1) and 42.46 kJ mol(-1), respectively. The liquid-film diffusion step might be the rate-limiting step. The thermodynamic parameters (ΔG(o), ΔH(o) and ΔS(o)) revealed that the adsorption process was spontaneous and exothermic under natural conditions. The interactions between EPS system and Pb (II) ions were investigated by qualitative analysis methods (i.e Zeta potential, FT-IR and EDAX). Based on the strong experimental evidence from the mass balance of the related elements participating in the sorption process, an ion exchange process was identified quantitatively as the major mechanism responsible for Pb (II) adsorption by EPS. Molar equivalents of both K(+) and Mg(2+) could be exchanged with Pb(2+) molar equivalents in the process and the contribution rate of ion exchange to adsorption accounted for 85.72% (Δmequiv = -0.000541)

E^2TAD: An Energy-Efficient Tracking-based Action Detector

Video action detection (spatio-temporal action localization) is usually the starting point for human-centric intelligent analysis of videos nowadays. It has high practical impacts for many applications across robotics, security, healthcare, etc. The two-stage paradigm of Faster R-CNN inspires a standard paradigm of video action detection in object detection, i.e., firstly generating person proposals and then classifying their actions. However, none of the existing solutions could provide fine-grained action detection to the "who-when-where-what" level. This paper presents a tracking-based solution to accurately and efficiently localize predefined key actions spatially (by predicting the associated target IDs and locations) and temporally (by predicting the time in exact frame indices). This solution won first place in the UAV-Video Track of 2021 Low-Power Computer Vision Challenge (LPCVC)

Huge magnetostriction in superconducting single-crystalline BaFe1.908_{1.908}Ni0.092_{0.092}As2_{2}

The performance of iron-based superconductors in high magnetic fields plays an important role for their practical application. In this work, we measured the magnetostriction and magnetization of BaFe$_{1.908}$Ni$_{0.092}$As$_{2}$ single crystals using pulsed magnetic fields up to 60 T and static magnetic fields up to 33 T, respectively. A huge longitudinal magnetostriction (of the order of 10$^{-4}$) was observed in the direction of the twin boundaries. The magnetization measurements evidence a high critical-current density due to strong bulk pinning. By using magnetization data with an exponential flux-pinning model, we can reproduce the magnetostriction curves qualitatively. This result shows that the magnetostriction of BaFe$_{1.908}$Ni$_{0.092}$As$_{2}$ can be well explained by a flux-pinning-induced mechanism.Comment: 4 pages, 3 figure

Manipulating Multiple Order Parameters via Oxygen Vacancies: The case of Eu0.5Ba0.5TiO3-{\delta}

Controlling functionalities, such as magnetism or ferroelectricity, by means of oxygen vacancies (VO) is a key issue for the future development of transition metal oxides. Progress in this field is currently addressed through VO variations and their impact on mainly one order parameter. Here we reveal a new mechanism for tuning both magnetism and ferroelectricity simultaneously by using VO. Combined experimental and density-functional theory studies of Eu0.5Ba0.5TiO3-{\delta}, we demonstrate that oxygen vacancies create Ti3+ 3d1 defect states, mediating the ferromagnetic coupling between the localized Eu 4f7 spins, and increase an off-center displacement of Ti ions, enhancing the ferroelectric Curie temperature. The dual function of Ti sites also promises a magnetoelectric coupling in the Eu0.5Ba0.5TiO3-{\delta}.Comment: Accepted by Physical Review B, 201