Two-dimensional (2D) multiferroic materials are recognized as promising candidates for next-generation nanodevices due to their tunable magnetoelectric coupling and distinctive physical phenomena. In this study, we proposed a novel 2D multiferroic van der Waals heterostructure (vdWH) by stacking atomic layers of ferroelectric In₂Se₃ and ferromagnetic MnI₃. Using first-principles calculations, we found that the MnI₃/In₂Se₃ vdWH exhibit robust metallic conductivity across various spin and polarization states, preserving the distinctive band characteristics of isolated In₂Se₃ and MnI₃. However, the alignment of Fermi levels causes the conduction band minimum (CBM) and valence band maximum (VBM) of In₂Se₃ and MnI₃ to shift relative to their original band structures. Remarkably, the MnI₃/In₂Se₃ with the upward polarization state of In₂Se₃ exhibits an Ohmic contact. Switching the polarization direction of In₂Se₃ from upward to downward can transform the MnI₃/In₂Se₃ vdWH from an Ohmic contact to a p-type Schottky contact, while also modifying its dipole moment, magnetic strength and direction. Based on these properties of MnI₃/In₂Se₃ vdWH, we designed the field-effect transistors (FETs) with high on/off rates and nonvolatile data storage device. Furthermore, the Schottky barrier heights (SBHs), magnetic moment, and dipole moment of MnI₃/In₂Se₃ vdWH can also be effectively regulated by reducing the interlayer distance. With the continuous reduction of the interlayer distance of MnI₃/In₂Se₃ vdWH, its easy magnetization axis is expected to shift from in-plane to out-of-plane. These findings offer new insights for the design and development of the next-generation spintronic and nonvolatile memory nanodevices.

Sarcopenia is an age-related syndrome characterized by the loss of skeletal muscle mass and function. Community screening, commonly used in early diagnosis, usually lacks features such as real-time monitoring, low cost, and convenience. This study introduces a promising approach to sarcopenia screening by dynamic plantar pressure monitoring. We propose a wearable flexible-printed piezoelectric sensing array incorporating barium titanate thin films. Utilizing a flexible printer, we fabricate the array with enhanced compressive strength and measurement range. Signal conversion circuits convert charge signals of the sensors into voltage signals, which are transmitted to a mobile phone via Bluetooth after processing. Through cyclic loading, we obtain the average voltage sensitivity (4.844 mV/kPa) of the sensing array. During a 6 m walk, the dynamic plantar pressure features of 51 recruited participants are extracted, including peak pressures for both sarcopenic and control participants before and after weight calibration. Statistical analysis discerns feature significance between groups, and five machine learning models are employed to screen for sarcopenia with the collected features. The results show that the features of dynamic plantar pressure have great potential in early screening of sarcopenia, and the Support Vector Machine model after feature selection achieves a high accuracy of 93.65%. By combining wearable sensors with machine learning techniques, this study aims to provide more convenient and effective sarcopenia screening methods for the elderly.

Vacancy defects are inevitable when synthesizing two-dimensional (2D) materials, and vacancy defects greatly affect the physical properties, such as magnetism and electronic properties. Currently, sufficient information is not available on whether and how the interaction of vacancy defects affects material properties and how to control these defects and their associated interaction for the development of new materials. In this study, the interaction between two adjacent vacancy defects of the gallium sulfide (GaS) monolayer is investigated using first-principles calculations based on density functional theory (DFT). The results indicate that the localized size of a Ga vacancy defect is the area within the S atoms second nearest to the neighboring vacancy defect. When the localized sizes of Ga vacancy defects intersect, a non-negligible interaction exists between the Ga vacancy defects. The interaction generally has been ignored by the traditional defect concentrations model but would affect the magnetic and electronic properties of the defective GaS monolayer. A vacancy defect cluster model (VDCM) is developed based on the system clustering method and then used to evaluate the interactions between vacancy defects. In order to check the reliability of the model, this research studies a defective MoS₂ monolayer as an example and compares the band gap and density of states (DOS) calculated by using different vacancy defect models, including VDCM. The results indicate that VDCM has good accuracy relative to the traditional vacancy concentration model. This means that with the help of VDCM the properties of the defective system could be calculated more accurately considering some extent of nonuniform distribution of defects based on DFT.

In present paper, boronizing was applied to N80 steel tube by pack boronizing, and its effect on mechanical properties, wear and corrosion of N80 tube steel was investigated. A dual-phase boride layer composed of FeB and F₂B phases was formed on the surface of the steel substrate in a hardness range of 1220–1340 HV. A set-up was designed to reduce usage of the boriding agent and accelerate the pipe's cooling process after boronizing treatment. In order to meet the tensile properties of N80 steel required by API SPEC 5L, different cooling methods were employed including annealing, normalizing, fan-cooling and graphite-bar assisted rapid cooling. Among these methods, graphite-bar assisted rapid cooling resulted in the highest amount of pearlite in the steel substrate and the highest mechanical properties, satisfying the mechanical properties of API SPEC 5L. The boronized N80 steel exhibited an abrasive wear mechanism and showed a higher wear resistance under a given sliding condition due to the great hardness and integrity of the boride layer, and it also displayed an excellent corrosion resistance in both H₂SO₄ and HCl acid environments.