The floating gate devices, as a kind of nonvolatile memory, obtain great application potential in logic-in-memory chips. The 2D materials have been greatly studied due to atomically flat surfaces, ...higher carrier mobility, and excellent photoelectrical response. The 2D ReS2 flake is an excellent candidate for channel materials due to thickness-independent direct bandgap and outstanding optoelectronic response. In this paper, the floating gate devices are prepared with the ReS2 /h-BN/Gr heterojunction. It obtains superior nonvolatile electrical memory characteristics, including a higher memory window ratio (81.82%), tiny writing/erasing voltage (±8 V/2 ms), long retention (>1000 s), and stable endurance (>1000 times) as well as multiple memory states. Meanwhile, electrical writing and optical erasing are achieved by applying electrical and optical pulses, and multilevel storage can easily be achieved by regulating light pulse parameters. Finally, due to the ideal long-time potentiation/depression synaptic weights regulated by light pulses and electrical pulses, the convolutional neural network (CNN) constructed by ReS2 /h-BN/Gr floating gate devices can achieve image recognition with an accuracy of up to 98.15% for MNIST dataset and 91.24% for Fashion-MNIST dataset. The research work adds a powerful option for 2D materials floating gate devices to apply to logic-in-memory chips and neuromorphic computing.
With the rapid growth of mobile communication data in recent years, visible light communication (VLC) technology based on GaN LEDs can cope with spectrum crises. However, as a light source device, ...the modulation bandwidth (MB) and light output power (LOP) are not ideal, which hinders communication quality and system reliability. This work proposes the high-reliability graphene (Gr)/GaN-based micro-light-emitting diodes (micro-LEDs) arrays with an LOP of 46 mW and a high -3-dB MB of 610 MHz at the current density of 6.7 kA/cm2. The various layers of Gr were adopted to increase carrier radiative recombination rate and current spreading in the quantum wells, which can effectively increase the reliability and LOP, as well as reduce the aging of LOP. With the appropriate layers of Gr, hole injection was enhanced and current expansion was improved accordingly, increasing the MB of the micro-LEDs. Possessing high MB, the micro-LEDs arrays also achieved high LOP and low aging rate under high temperature and humidity conditions by introducing the appropriate number of Gr layers, which will be beneficial to improve the lifespan and reliability of the micro-LEDs. The optimistic results in this letter possess high potential of providing high LOP and MB light sources in VLC system.
A modified version of the Monkman-Grant equation, which can provide a more accurate means of predicting creep rupture life than the standard Monkman-Grant formula, has been investigated for Gr.91 ...using creep data in the NIMS Creep Data Sheets at 450–725 °C. The maximum time to rupture tr was 1.2 × 105 h. The tr versus minimum creep rate ε˙min plot, which is called the Monkman-Grant relation, deviates downward at low stresses and long times. The difference between the maximum and minimum tr at a same ε˙min becomes more significant with decreasing stress and increasing test duration. Better correlation of the tr with the ε˙min is not obtained by the replacement of tr with (tr/εr), where εr is the total or rupture strain. The magnitude of data scattering is larger in the (tr/εr) versus ε˙min plot than in the tr versus ε˙min plot. The (tr/εm), where εm is the strain to minimum creep rate, is inversely proportional to the ε˙min over a wide range of stress, temperature and test duration and the magnitude of data scattering is only a little bit even at low stresses and long times. The (tr/εm) versus ε˙min plot gives us more reliable relation for Gr.91 than the tr versus ε˙min and (tr/εr) versus ε˙min plots.
•Monkman-Grant eq. with “strain to minimum creep rate” accurately predicts creep life.
Although postpartum depression (PPD) is the leading cause of disability worldwide, its molecular mechanisms are poorly understood. Recent evidence has suggested that impaired glucocorticoid receptor ...(GR), the signaling of key molecules of the HPA axis, plays a key role in the behavioral and neuroendorcrine alterations of major depression. However, the role of GR in postpartum period, which following with the abrupt withdrawal of placental corticotropin releasing hormone (CRH) and resulting in a re-equilibration of the maternal HPA axis in the days of post-delivery, is still not entirely clear. Previously, a hormone-simulated pregnancy (HSP), and the subsequent ‘postpartum’ withdrawal in estrogen has been employed to mimic the fluctuations in estradiol associated with pregnancy and postpartum. Using the HSP model, we investigated here the effect of ‘postpartum’ withdrawal in estrogen as well as depression- and anxiety-like behavior by intra-hippocampal infusion with GR inhibitor-RU486. Following the successful acquisition of PPD model by withdrawal in estrogen, reduced GR expression was observed in hippocampus. Further, HSP-rats suffered intra-hippocampal RU486 infusion presented depression- and anxiety-like behavior as postpartum depression. Together, these results suggest an important, though complex, role for GR in the behavioral regulation of postpartum depression.
•A hormone-simulated pregnancy (HSP), and the subsequent ‘postpartum’ withdrawal in estrogen was to mimic postpartum depression.•Postpartum estrogen withdrawal reduced hippocampal glucocorticoid receptor (GR) expression.•HSP-rats intra-hippocampal infusion with GR inhibitor-RU486 exhibited depression- and anxiety-like behavior
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