The Nonvolatile Memory and Neuromorphic Simulation of ReS2 /h-BN/Graphene Floating Gate Devices Under Photoelectrical Hybrid Modulations.

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.

[Studies on chemical constituents from the root of Polygonatum kingianum].

OBJECTIVE: To investigate the anti-HIV constituents from the root of Polygonatum kingianum. METHOD: The compounds were isolated by column chromatography on silica gel, Sephadex LH-20, MCI-gel CHP-20P and their structures were determined on the basis of their spectroscopic evidence including IR, MS and NMR data. RESULT: 13 compounds were isolated, of which nine compounds were identified as liquiritigenin, isoliquiritigenin, 4', 7-dihydroxy-3'-methoxyisoflavone, (6aR, 11aR)-10-hydroxy-3, 9-dimethoxypterocarpan, 5-hydroxymethyl-2-furancarboxaldehyde, salicylic acid, n-butyl-beta-D-fructopyranoside, n-butyl-beta-D-fructofuranoside, n-butyl-alpha-D-fructofuranoside. CONCLUSION: Compounds 1-6 were obtained from this plant for the first time.