Integration of Ultrathin Hafnium Oxide with a Clean van der Waals Interface for Two-Dimensional Sandwich Heterostructure Electronics.

Integrating high-κ dielectrics with a small equivalent oxide thickness (EOT) with two-dimensional (2D) semiconductors for low-power consumption van der Waals (vdW) heterostructure electronics remains challenging in meeting both interface quality and dielectric property requirements. Here, we demonstrate the integration of ultrathin amorphous HfOx sandwiched within vdW heterostructures by the selective thermal oxidation of HfSe2 precursors. The self-cleaning process ensures a high-quality interface with a low interface state density of 1011-1012 cm-2 eV-1. The synthesized HfOx displays excellent dielectric properties with an EOT of ∼1.5 nm, i.e., a high κ of ∼16, an ultralow leakage current of 10-6 A/cm2, and an impressively high breakdown field of 9.5 MV/cm. This facilitates low-power consumption vdW heterostructure MoS2 transistors, demonstrating steep switching with a low subthreshold swing of 61 mV/decade. This one-step integration of high-κ dielectrics into vdW sandwich heterostructures holds immense potential for developing low-power consumption 2D electronics while meeting comprehensive dielectric requirements.

Aerobic granulation in a sequencing batch reactor for the treatment of piggery wastewater.

This study investigated the formation of aerobic granules fed with digested piggery wastewater. After 42 days of cultivation, small yellow granules with mean diameter of 0.4 mm were first observed in the reactor. Scanning electron microscope pictures showed the granules were compact, round structures with clear outer shapes and mainly composed of filamentous bacteria. Maximum chemical oxygen demand and ammonia removal ratios were 90.1 and 91.7%, respectively. The Monod equation, which was used to describe ammonium utilization, yielded a maximum rate of 6.25 mg (g volatile suspended solids)(-1) h(-1). The measurement of extracellular polymeric substances (EPS) content and three-dimensional excitation and emission matrix results showed that the EPS concentration increased during the granulation process. Fluorescence in situ hybridization analysis showed significant amounts of nitrifying bacteria in the aerobic granules. Results in this study provide insights to the treatment of piggery wastewater using aerobic granular sludge.

Work from home or office during the COVID-19 pandemic: The different chain mediation models of perceived organizational support to the job performance.

With the coronavirus pandemic in 2019 (COVID-19), work from home (WFH) has become a frequent way of responding to outbreaks. Across two studies, we examined how perceived organizational support influences job performance when employees work in office or work from home. In study 1, we conducted a questionnaire survey of 162 employees who work in office. In study 2, we conducted a questionnaire survey of 180 employees who work from home. We found that perceived organizational support directly affected job performance when employees work in office. When employees work from home, perceived organizational support could not affect job performance directly. However, it could influence job performance indirectly through the separate mediating effects of job satisfaction and work engagement. These findings extend our understanding of the association of perceived organizational support and job performance and enlighten enterprises on improving employees' job performance during the COVID-19 pandemic.

A Light-Programmed Rewritable Lattice-Mediated Multistate Memory for High-Density Data Storage.

Mainstream non-volatile memory (NVM) devices based on floating gate structures or phase-change/ferroelectric materials face inherent limitations that compromise their suitability for long-term data storage. To address this challenge, a novel memory device based on light-programmed lattice engineering of thin rhenium disulfide (ReS2 ) flakes is proposed. By inducing sulfur vacancies in the ReS2 channel through light illumination, the device's electrical conductivity is modified accordingly and multiple conductance states for data storage therefore are generated. The device exhibits more than 128 distinct states with linearly increasing conductance, corresponding to a sevenfold increase in storage density. Through further optimization to achieve atomic-level precision in defect creation, it is possible to achieve even higher storage densities. These states are extremely stable in vacuum or inert ambient showing long retention of >10 years, while they can be erased upon exposure to the air. The ReS2 memory device can maintain its stability over multiple program-erase operation cycles and shows superior wavelength discrimination capability for incident light in the range of 405-785 nm. This device represents a significant contribution to NVM technology by offering the ability to store information in multistate memory and enabling filter-free color image recorder applications.

Intelligent Assessment of Mental Health Based on Multisource Information Fusion.

Mental health problems will seriously damage social harmony and family happiness. This paper proposes a study on mental health intelligence assessment based on multisource information fusion. Combining the data description of UPI and SCL-90 and the corresponding task requirement analysis, the multisource information fusion visualization based on the Circos diagram is designed and realized, and the parallel coordinate visualization is established. The MDS algorithm is used to project multidimensional survey objects into low-dimensional visualization space, and the actual UPI and SCL-90 questionnaire data for 278 students of a certain major at a university provided by the cooperative unit are used. The results show that the mental health problems of student A are serious, and the symptoms of depression and schizophrenia are prominent, so it is necessary to seek psychological experts for corresponding treatment in time. By contrast, student B's mental health problems are also serious, and the user judges that student B still needs further diagnosis and treatment. The correlation analysis results of multisource information fusion are roughly the same as the actual situation, which is convincing. Therefore, the multisource mental health information fusion of college students has a certain correlation and complementarity.

How Social Support Impact Teachers' Mental Health Literacy: A Chain Mediation Model.

Teachers have an important social role, and their mental health literacy is very important to their own abilities as educators and to the growth and development of those they educate. This study explored the mechanism underlying the influence of social support on teachers' mental health literacy by conducting a questionnaire survey of 573 teachers. The results showed that social support can influence teachers' mental health literacy not only through the separate effects of life satisfaction and coping tendency but also through the chain mediation effect of life satisfaction and coping tendency; however, the direct effect of social support on the teachers' mental health literacy is not significant. This study is conducive to understanding the internal mechanism underlying the relationship between social support and mental health literacy. It reminded us that when formulating mental health literacy promotion programs for teachers, we should not only provide adequate social support to improve but also should pay attention to improvements in their coping tendencies and life satisfaction.

A Single-Electron Transistor Made of a 3D Topological Insulator Nanoplate.

Quantum confined devices of 3D topological insulators are proposed to be promising and of great importance for studies of confined topological states and for applications in low-energy-dissipative spintronics and quantum information processing. The absence of energy gap on the topological insulator surface limits the experimental realization of a quantum confined system in 3D topological insulators. Here, the successful realization of single-electron transistor devices in Bi2 Te3 nanoplates using state-of-the-art nanofabrication techniques is reported. Each device consists of a confined central island, two narrow constrictions that connect the central island to the source and drain, and surrounding gates. Low-temperature transport measurements demonstrate that the two narrow constrictions function as tunneling junctions and the device shows well-defined Coulomb current oscillations and Coulomb-diamond-shaped charge-stability diagrams. This work provides a controllable and reproducible way to form quantum confined systems in 3D topological insulators, which should greatly stimulate research toward confined topological states, low-energy-dissipative devices, and quantum information processing.

Strong spin-orbit interaction and magnetotransport in semiconductor Bi2O2Se nanoplates.

Semiconductor Bi2O2Se nanolayers of high crystal quality have been realized via epitaxial growth. These two-dimensional (2D) materials possess excellent electron transport properties with potential application in nanoelectronics. It is also strongly expected that the 2D Bi2O2Se nanolayers can be an excellent material platform for developing spintronic and topological quantum devices if the presence of strong spin-orbit interaction in the 2D materials can be experimentally demonstrated. Herein, we report the experimental determination of the strength of spin-orbit interactions in Bi2O2Se nanoplates through magnetotransport measurements. The nanoplates are epitaxially grown by chemical vapor deposition, and the magnetotransport measurements are performed at low temperatures. The measured magnetoconductance exhibits a crossover behavior from weak antilocalization to weak localization at low magnetic fields with increasing temperature or decreasing back gate voltage. We have analyzed this transition behavior of magnetoconductance based on an interference theory, which describes quantum correction to the magnetoconductance of a 2D system in the presence of spin-orbit interaction. Dephasing length and spin relaxation length are extracted from the magnetoconductance measurements. Compared to the case of other semiconductor nanostructures, the extracted relatively short spin relaxation length of ∼150 nm indicates the existence of a strong spin-orbit interaction in Bi2O2Se nanolayers.

Weak antilocalization and electron-electron interaction in coupled multiple-channel transport in a Bi2Se3 thin film.

The electron transport properties of a topological insulator Bi2Se3 thin film are studied in Hall-bar geometry. The film with a thickness of 10 nm is grown by van der Waals epitaxy on fluorophlogopite mica and Hall-bar devices are fabricated from the as-grown film directly on the mica substrate. Weak antilocalization and electron-electron interaction effects are observed and analyzed at low temperatures. The phase-coherence length extracted from the measured weak antilocalization characteristics shows a strong power-law increase with decreasing temperature and the transport in the film is shown to occur via coupled multiple (topological surface and bulk states) channels. The conductivity of the film shows a logarithmical decrease with decreasing temperature and thus the electron-electron interaction plays a dominant role in quantum corrections to the conductivity of the film at low temperatures.

Patterning two-dimensional chalcogenide crystals of Bi2Se3 and In2Se3 and efficient photodetectors.

Patterning of high-quality two-dimensional chalcogenide crystals with unique planar structures and various fascinating electronic properties offers great potential for batch fabrication and integration of electronic and optoelectronic devices. However, it remains a challenge that requires accurate control of the crystallization, thickness, position, orientation and layout. Here we develop a method that combines microintaglio printing with van der Waals epitaxy to efficiently pattern various single-crystal two-dimensional chalcogenides onto transparent insulating mica substrates. Using this approach, we have patterned large-area arrays of two-dimensional single-crystal Bi2Se3 topological insulator with a record high Hall mobility of ∼1,750 cm(2) V(-1) s(-1) at room temperature. Furthermore, our patterned two-dimensional In2Se3 crystal arrays have been integrated and packaged to flexible photodetectors, yielding an ultrahigh external photoresponsivity of ∼1,650 A W(-1) at 633 nm. The facile patterning, integration and packaging of high-quality two-dimensional chalcogenide crystals hold promise for innovations of next-generation photodetector arrays, wearable electronics and integrated optoelectronic circuits.