No abstract

No abstract

The integration and cooperation of nociceptors, neurons and synapses in the biological nervous system empower humans to efficiently perceive and process noxious information for avoiding dangers. Inspired by biological nervous systems, current artificial demonstrations include electrolyte-gate transistors, electrochemical metallization resistive switching devices and halide perovskite-based memristors. However, these devices suffer from integration difficulties and instability issues. Herein, we introduce a complementary metal oxide semiconductor (CMOS)-compatible simple and stable Pt/V 2 O 5 /Pt sandwich structure and carefully construct and modulate the suboxide V 2 O 5−x and Mott VO 2 nanochannels in the layered V 2 O 5 matrix to simulate brain-like processing and nervous pain perception functions, respectively. Simulation results demonstrate that the recognition accuracy of handwritten digits reaches 80% after only 5 training epochs and 89% after 52 epochs in a convolutional neural network based on the V 2 O 5−x nanochannel synaptic device. The nociceptor with all key characteristics is perfectly imitated based on the VO 2 nanochannel threshold switching device. Especially, an ultralow threshold level of 0.4 V and sub-millisecond incubation time are observed in the nociceptor simulation, which could be needed in special injury situations. The proposed drift and Mott nanochannels in one device hold a tremendous potential as synaptic and nociceptive emulators for artificial intelligence systems.

Coal seam is a sedimentary body with complex pore system. The gas adsorption property of coal is greatly determined by the adsorption‐pores (<100 nm), and the fractal dimension can be used an index to estimate the impact of the adsorption‐pores on the methane adsorption capacity of various rank coals. In this paper, low‐temperature N2 adsorption and H2O adsorption methods were used to study the adsorption‐pores structure and its fractal features. The results show that the development of adsorption‐pores closely depends on the coalification, and the degree of pore development exhibits a U‐shaped trend with increasing coal rank. Additionally, the pore size distributions of coal samples from N2 adsorption analysis and H2O adsorption analysis are similar, especially for samples LH7 and WLH8. Fractal analysis indicates that D2(N2) (0.5 < P/P0 < 1) can more accurately characterize the fractal features of adsorption‐pores than D2(H2O), which may be a result of the significant coal‐H2O interaction. Moreover, D2(N2) has stronger correlations with the coal pore parameters. With the increase in D2(N2), the Langmuir volume first decreases and then increases, which is probably associated with the competition effect of the pore structure and surface irregularity of coal. When D2(N2) < 2.7‐2.8, the pore structure plays a key role, while for D2(N2) > 2.7‐2.8, the influence of the specific surface area is more prominent. The equilibrium moisture content of the coal samples also has a positive correlation with D2, except for low‐rank coal sample YZG2 due to the presence of a large amount of oxygen‐containing functional groups, which increases its water‐holding capacity.

No abstract

Magnesium isotopic compositions of evaporite deposits may record information concerning brine evolution during deposition. We report Mg isotopic values (δ26MgDSM3) measured from an evaporite deposit of langbeinite (K2Mg2(SO4)3) found in the Permian Salado Formation. We used these data to model Mg isotope fractionation between langbeinite and its parent brine. In addition, both measured and theoretical results are used to estimate precipitation temperature and interpret depositional environment. The Salado langbeinite δ26Mg values are relatively low and fall within a relatively narrow range (–4.12 ± 0.03‰ to −3.81 ± 0.07‰). Equilibrium fractionation factors between langbeinite and aqueous Mg2+ solutions were calculated using quantum chemical density functional theory. All computations were performed at the B3LYP/6‐31 + G(d,p) level. Solvation effects were addressed using a solvent model (“water‐droplet” approach) and mineral structures were investigated using volume variable cluster models (VVCM). The equilibrium Mg isotopic fractionation factors α between langbeinite and model brine solution we obtained are 1.0005, 1.0004, and 1.0003 (Δ26Mglangb‐water≈103lnα = 0.473‰, 0.390‰, and 0.322‰) at 10°C, 25°C, and 40°C, respectively. These relatively large equilibrium fractionation factors indicate significant Mg isotope fractionation between langbeinite and its parent brine during precipitation, as langbeinite preferentially incorporates the heavier 26Mg and 25Mg isotopes. Rayleigh distillation modeling of the Salado langbeinite's relatively light Mg isotopic composition requires δ26MgDSM3 values of −4‰ for the parent brine. Models favor a precipitation temperature as high as 40°C under equilibrium conditions. Potential disequilibrium precipitation conditions suggested by Mg isotopic data also imply rapid deposition in a hot, arid sedimentary environment prevailing in the southwestern U.S. during the Late Permian.

It is important for life safety and scientific research to design new sensing materials for detecting CO, CH4 and CO2 from environment. We theoretically designed a new Cr-doped graphene-like hexagonal borophene (CrB6) as potential sensor material for these gases. Carrying out firstprinciples density-functional calculations, we calculated the adsorption energy, band structure, adsorption distance, charge transfer, charge density difference, density of states and partial density of states of CO, CH4 and CO2 gas molecules absorbed on CrB6 monolayer. The calculated resultsshow that the adsorption behavior of CO is different from those of CH4 and CO2. CO adsorbed on CrB6 monolayer prefers chemisorption while CH4 and CO2 adsorbed on CrB6 monolayer prefers physisorption. As a result, the different adsorption behaviors have significant influence on the band structures and density of states of CrB6 monolayer. We hope that our results can help experimentalists synthesize better sensor materials based on hexagonal borophene.

No abstract