The present study aimed to explore the prevalence and frequency of child psychological maltreatment and its correlated factors in Chinese families. A cross-sectional investigation was conducted among 1,002 parents of primary school students in Yuncheng City, China. Data were collected using the self-report questionnaire anonymously. Results showed that 696 (69.5%) surveyed parents had different extents of psychological maltreatment toward their children in the past 3 months. The high prevalence of parental psychology maltreatment was significantly associated with high scores on parental over-reactivity and low scores on recognition of child psychology maltreatment. These findings indicate that it is urgent to develop cultural interventions to raise parents' awareness of preventing child psychological maltreatment and to help parents use nonviolent child rearing in China.
Two-dimensional material MoS2 has excellent optical and electrical characteristics and a controllable energy band structure, leading to a high potential value for designing photodetectors. In this work, a kind of van der Waals heterostructure composed of AlN and a MoS2 photodetector was fabricated. The optical properties of MoS2 can be improved by the polarization effect of AlN. On this basis, with a 3 nm thick Al2O3 layer deposited on the MoS2 layer, the strain effects were also investigated to improve the performance of the detector. The result showed that under an illumination of 365 nm wavelength, the stress liner device showed excellent performance relative to the control device and the photocurrent and responsivity were improved by more than five times. Our work provides guidance for developing heterostructure photoelectric devices and also proves the role of strain engineering in improving the performance of photodetectors.
A suppressor of unwanted higher order modes in a wideband tracking corrugated horn is proposed and a new restraining principle called the local restraint is introduced. The cross-polarization peak level of the horn can be reduced over 8.5 dB in the transmitting band by this suppressor.
The exciton, a quasi-particle that creates a bound state of an electron and a hole, is typically found in semiconductors. It has attracted major attention in the context of both fundamental science and practical applications. Transition metal dichalcogenides (TMDs) are a new class of 2D materials that include direct band-gap semiconductors with strong spin-orbit coupling and many-body interactions. Manipulating new excitons in semiconducting TMDs could generate a novel means of application in nanodevices. Here, the observation of high-energy excitonic peaks in the monolayer-MoS2 on a SrTiO3 heterointerface generated by a new complex mechanism is reported, based on a comprehensive study that comprises temperature-dependent optical spectroscopies and first-principles calculations. The appearance of these excitons is attributed to the change in many-body interactions that occurs alongside the interfacial orbital hybridization and spin-orbit coupling brought about by the excitonic effect propagated from the substrate. This has further led to the formation of a Fermi-surface feature at the interface. The results provide an atomic-scale understanding of the heterointerface between monolayer-TMDs and perovskite oxide and highlight the importance of spin-orbit-charge-lattice coupling on the intrinsic properties of atomic-layer heterostructures, which open up a way to manipulate the excitonic effects in monolayer TMDs via an interfacial system.
Phototransistors based on monolayer transition metal dichalcogenides (TMD) have high photosensitivity due to their direct band gap transition. However, there is a lack of understanding of the effect of metal contacts on the performance of atomically thin TMD phototransistors. Here, we fabricate phototransistors based on large-area chemical vapor deposition (CVD) tungsten diselenide (WSe2) monolayers contacted with the metals of different work function values. We found that the low Schottky-contact WSe2 phototransistors exhibit a very high photo gain (105) and specific detectivity (1014Jones), values higher than commercial Si- and InGaAs-based photodetectors; however, the response speed is longer than 5 s in ambient air. In contrast, the high Schottky-contact phototransistors display a fast response time shorter than 23 ms, but the photo gain and specific detectivity decrease by several orders of magnitude. Moreover, the fast response speed of the high Schottky-contact devices is maintained for a few months in ambient air. This study demonstrates that the contact plays an important role in TMD phototransistors, and barrier height tuning is critical for optimizing the photoresponse and photoresponsivity.
We study a quasi-one-dimensional non-reciprocal Hermitian hourglass photonic lattice that can accomplish multiple functions. Under the effect of non-reciprocal coupling, this lattice can produce an energy isolation effect, two kinds of flatbands, and energy band inversion. The excitation and propagation of a single energy band and multiple energy bands can be realized; in the flatband condition, the system has compact localized states, and the flatbands can be excited by a straightforward method. Our findings advance the theory of energy band regulation in artificial photonic lattices.
Abstract Metallic tungsten disulfide (WS 2 ) monolayers have been demonstrated as promising electrocatalysts for hydrogen evolution reaction (HER) induced by the high intrinsic conductivity, however, the key challenges to maximize the catalytic activity are achieving the metallic WS 2 with high concentration and increasing the density of the active sites. In this work, single-atom-V catalysts (V SACs) substitutions in 1T-WS 2 monolayers (91% phase purity) are fabricated to significantly enhance the HER performance via a one-step chemical vapor deposition strategy. Atomic-resolution scanning transmission electron microscopy (STEM) imaging together with Raman spectroscopy confirm the atomic dispersion of V species on the 1T-WS 2 monolayers instead of energetically favorable 2H-WS 2 monolayers. The growth mechanism of V SACs@1T-WS 2 monolayers is experimentally and theoretically demonstrated. Density functional theory (DFT) calculations demonstrate that the activated V-atom sites play vital important role in enhancing the HER activity. In this work, it opens a novel path to directly synthesize atomically dispersed single-metal catalysts on metastable materials as efficient and robust electrocatalysts.
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