RESUMEN
Lithium ion transport in a polycrystalline solid-state electrolyte (SSE) is directly linked to the properties of lithium ion batteries. Grain boundaries (GBs), as essential defects in SSE, have been found to play a significant role in the overall kinetics of lithium ion transport, however, the mechanism is not well understood due to the complex role of GBs. The GBs could affect the overall kinetics of ionic transport in the SSEs in two ways: (i) Li/Na diffusivities inside the GBs could be different from those in the bulk, and (ii) point defect segregation at the GBs. The first aspect is well recognized, whereas the second one has been rarely studied. In this study, a combination of first principles and phase field calculations were performed, in which the interaction between point defects and grain boundaries were considered at different scales, to reveal the role of GBs in the overall ionic conduction of SSE anti-perovskite Li3ClO. The results show that defect segregation, which varies significantly with the GB orientation, reinforces the negative contribution of GBs on the overall ionic diffusivity by approximately one-order of magnitude. This study could help improve the fundamental understanding of ionic transport in polycrystalline SSEs, and provide guidance for the design of new SSEs with excellent ionic conductivity.
RESUMEN
High-performance artificial synaptic devices with rich functions are highly desired for the development of an advanced brain-like neuromorphic system. Here, we prepare synaptic devices based on a CVD-grown WSe2 flake, which has an unusual morphology of nested triangles. The WSe2 transistor exhibits robust synaptic behaviors such as excitatory postsynaptic current, paired-pulse facilitation, short-time plasticity, and long-time plasticity. Furthermore, due to its high sensitivity to light illumination, the WSe2 transistor exhibits excellent light-dosage-dependent and light wavelength-dependent plasticity, which endow the synaptic device with more intelligent learning and memory functions. In addition, WSe2 optoelectronic synapses can mimic "learning experience" behavior and associative learning behavior like the brain. An artificial neural network is simulated for pattern recognition of hand-written digital images in the MNIST data set and the best recognition accuracy could reach 92.9% based on weight updating training of our WSe2 device. Detailed surface potential analysis and PL characterization reveal that the intrinsic defects generated in growth are dominantly responsible for the controllable synaptic plasticity. Our work suggests that the CVD-grown WSe2 flake with intrinsic defects capable of robust trapping/de-trapping charges holds great application prospects in future high-performance neuromorphic computation.
RESUMEN
Mercury (Hg) significantly inhibits maize (Zea mays L.) production, which could be aggravated by water deficit (WD) due to climate change. However, there is no report on the maize in response to combined their stresses. This work was conducted for assessing the response and adaptive mechanism of maize to combined Hg and WD stress using two maize cultivars, Xianyu (XY) 335 and Yudan (YD) 132. The analysis was based on plant growth, physiological function, and transcriptomic data. Compared with the single Hg stress, Hg accumulation in whole plant and translocation factor (TF) under Hg+WD were increased by 64.51 % (1.44 mg kg-1) and 260.00 %, respectively, for XY 335; and 50.32 % (0.62 mg kg-1) and 220.02 %, respectively, for YD 132. Combined Hg and WD stress further increased the reactive oxygen species accumulation, aggravated the damage of the thylakoid membrane, and decreased chlorophyll content compared with single stress. For example, Chl a and Chl b contents of XY 335 were significantly decreased by 48.67 % and 28.08 %, respectively at 48 h after Hg+WD treatment compared with Hg stress. Furthermore, transcriptome analysis revealed that most of down-regulated genes were enriched in photosynthetic-antenna proteins, photosynthesis, chlorophyll and porphyrin metabolism pathways (PsbS1, PSBQ1 and FDX1 etc.) under combined stress, reducing light energy capture and electron transport. However, most genes related to the brassinosteroids (BRs) signaling pathway were up-regulated under Hg+WD stress. Correspondingly, exogenous BRs significantly enhanced the maize tolerance to stress by decreasing Hg accumulation and TF, and raising activities of antioxidant enzyme, the content of chlorophyll and photosynthetic performance. The PI, Fv/Fm and Fv/Fo of Hg+WD+BR treatment were increased by 29.88 %, 32.06 %, and 14.56 %, respectively, for XY 335 compared to Hg+WD. Overall, combined Hg and WD stress decreased photosynthetic efficiency by adversely affecting light absorption and electron transport, especially in stress-sensitive variety, but BRs could alleviate the inhibition of photosynthesis, providing a novel strategy for enhancing crop Hg and WD tolerance and food safety.