In this paper, we reported the mechanism of a bimodal Weibull distribution for TDDB of gate dielectric in GaN MISHEMT. It is shown that the properties of traps in the dielectric layer would have a great influence on the long time reliability and life time prediction process.
Spatiotemporal recognition of multiple mechanical stimuli is essential for electronic skin (e-skin), which can provide more complete and accurate interaction information to enable elaborated functions, such as gesture recognition, object manipulation, and fine tactile discrimination. However, nonspecific sensor response and performance sacrifice for integration limit the perceptual capability of the current systems. Here, we report a bioinspired e-skin that can measure strain, shear and pressure independently with direction information using three-dimensional integrated, mechanically isolated multiple sensors. Novel microstructures of collapsed nanocone clusters, hemi-ellipsoids, and wrinkles are introduced in different sensors to achieve a gauge factor of 6 with a linear working range of 80% (linearity > 0.99) for strain, a sensitivity of 0.1 N−1 for shear force, and a sensitivity of 3.78 kPa−1 for pressure, and all of these sensors possess short response times on the order of 100 ms. The independent, highly sensitive, and fast response of these sensors makes real-time recording and mapping of multiple mechanical stimuli to be achieved. Multi-touch gesture recognition and perception of a red bean (0.065 g) in the hand are demonstrated to illustrate the potential applications in wearables, robotics and bionic prostheses.
A new type of solar active carbon-doped Bi3O4Br catalyst was synthesized by combining hydrothermal and post-thermal treatment. The activity of the material under sunlight and visible light was 3.3 times and 2.7 times that of Bi3O4Br, respectively. The C-doping on Bi3O4Br nanosheets increased the built-in electric field strength, thus significantly promoted the migration of charge carriers and enhanced the photocatalytic activity. In addition, replacing Br with C with a smaller atomic radius can shorten the interlayer spacing, which is beneficial to carrier separation. Experiments showed that the doping of C shortened the semiconductor band gap by 9.8% and expanded the absorption range of visible light. Among the photogenerated reactive species, h+ played a major role in the degradation of 1-methylpyrene (a typical polycyclic aromatic hydrocarbons), followed by O2∙- and •OH. Based on intermediate analysis and DFT calculation, we proposed the degradation mechanism and pathways. Quantitative structure–activity relationship (QSAR) analysis showed that some toxic intermediates were produced during the photocatalysis process, but the overall environmental risk was greatly reduced. This work provides new perspective for understanding non-metallic doping in semiconductor photocatalysts to enhance the built-in electric field, and this technology can be extended to other semiconductor materials.
In bioaugmented wastewater treatment systems, it is essential for recalcitrant pollutant-degrading bacteria to form biofilms. Inducing biofilm formation in these bacteria, however, is challenging as it involves multiple inter-related regulating pathways and environmental factors. Herein, we report the remarkable promoting effect of Ca2+ on biofilm formation of two novel pyridine-degrading bacteria with poor innate biofilm-forming capabilities, Pseudomonas sp. ZX01 and Arthrobacter sp. ZX07. The roles of Ca2+ in different biofilm development stages were investigated. Our data showed strong influences of Ca2+ on the initial attachment of the two strains onto positively charged glass surfaces by altering cell surface charge as well as the cation bridging effect. Contrary to many other biofilm promoting mechanisms, Ca2+ downregulated the extracellular polymeric substances (EPS) production per cell in both Pseudomonas sp. ZX01 and Arthrobacter sp. ZX07, while increasing biofilm biomass. This is attributed to the strong cationic bridging between Ca2+ and EPS which can elevate the efficiency of the extracellular products in binding bacterial cells. Furthermore, Ca2+ increased the protein-to-polysaccharide (PN/PS) ratio in biofilm EPS of both strains, which favored cell aggregation, and biofilm establishment by increasing the hydrophobicity of cell surfaces. More intriguingly, the intracellular c-di-GMP, which can drive the switch of bacterial lifestyle from planktonic state to biofilm state, was also elevated markedly by exogenous Ca2+. Taken together, these results would be of guidance for applying the two strains into bioaugmented biofilm reactors where Ca2+ supplement strategy can be employed to facilitate their biofilm formation on the surfaces of engineering carriers.