Artificial structures made of stacked two-dimensional crystals have recently been the focus of intense research activity. As in twisted or stacked graphene layers, these structures can show unusual ...behaviours and new phenomena. Among the various layered compounds that can be exfoliated, transition-metal dichalcogenides exhibit interesting properties governed by their structural symmetry and interlayer coupling, which are highly susceptible to stacking. Here, we obtain-by folding exfoliated MoS2 monolayers-MoS2 bilayers with different stacking orders, as monitored by second harmonic generation and photoluminescence. Appropriate folding can break the inversion symmetry and suppress interlayer hopping, evoking strong valley and spin polarizations that are not achieved in natural MoS2 bilayers of Bernal stacking. It can also enlarge the indirect bandgap by more than 100meV through a decrease in the interlayer coupling. Our work provides an effective and versatile means to engineer transition-metal dichalcogenide materials with desirable electronic and optical properties.
Progonocimicids are one of key representatives from the Middle-Late Jurassic Daohugou biota, the early assemblage of the Yanliao biota. Here we describe a new progonocimicid species, Cicadocoris ...henanensis sp. nov., from the Middle Jurassic Jiyuan Basin in central China. This not only represents a novel case indicating the abundance of progonocimicids during the Jurassic but also provides additional evidence substantiating the stratigraphic correlation between the Yangshuzhuang Formation in the Jiyuan Basin and the Haifanggou Formation in the Yanliao Region.
A new genus and species of the extinct cicadomorphan family Hylicellidae, Vetusala maculata gen. et sp. nov., is described and illustrated based on a forewing specimen from the Middle-Upper Triassic ...Yanchang Formation of northern China. The new discovery represents the earliest and the first definite Triassic member of Hylicellidae in China, further shedding light on the diversity of cicadomorphan insects in the Tongchuan entomofauna.
In the standard kernel partial least squares (KPLS), the mapped data in the feature space need to be centralized before extraction of new score vectors. However, each vector of the centralized ...variables is often uniformly distributed, and some original features that can reflect the contribution of each variable to fault diagnosis might be lost. As a result, it might lead to misleading interpretations of the principal components and to increasing the false alarm rate for fault detection. To cope with these difficulties, a novel data-driven framework using KPLS based on an optimal preference matrix (OPM) is presented in this paper. In fault monitoring, an OPM is proposed to change the distribution of the variable and to readjust the eigenvalues of the covariance matrix. To obtain the OPM, the objective function can be determined in terms of the squared prediction error and Hotelling's T-squared (T 2 ) statistics. Two optimization algorithms, genetic algorithm and particle swarm optimization algorithm, are extended to maximize effectiveness of the OPM. Compared with traditional methods, the proposed method can overcome the drawback of original features loss of the centralized mapped data in the feature subspace and improve the accuracy of fault diagnosis. Also, few extra computation costs are needed in fault detection. Extensive experimental results on both the Tennessee Eastman benchmark process and the case study of the aluminum electrolytic production process give credible fault diagnosis.
For centrosymmetric materials such as monolayer graphene, no optical second-harmonic generation (SHG) is generally expected, because it is forbidden under the electric-dipole approximation. Yet we ...observe a strong, doping-induced SHG from graphene, with its highest strength comparable to the electric-dipole-allowed SHG in noncentrosymmetric 2D materials. This novel SHG has the nature of an electric-quadrupole response, arising from the effective breaking of inversion symmetry by optical dressing with an in-plane photon wave vector. More remarkably, the SHG is widely tuned by carrier doping or chemical potential, being sharply enhanced at Fermi-edge resonances but vanishing at the charge neutral point that manifests the electron-hole symmetry of massless Dirac fermions. This striking behavior in graphene, which should also arise in graphenelike Dirac materials, expands the scope of nonlinear optics and holds the promise of novel optoelectronic and photonic applications.
In-memory computing based on memristor is a promising solution to accelerate on-chip deep neural networks. Concerning the nonideal factors of the device analog behaviors, binary neural network (BNN) ...with ±1 weight and 0/+1 neuron is an alternative route to better employ the binary memristors with high technical maturity. In this article, we demonstrate a select column scheme for the BNN inference accelerator. By incorporating the performance of a W/AlO x /Al 2 O 3 /Pt memristor, the BNN shows high robustness and achieves a high recognition accuracy of 98.31% on the MNIST data set. We further propose a bit error model to investigate the impact of device error on recognition accuracy. The effects of device variation and nonideal input are also considered. The results show that the accuracy keeps satisfying (more than 90%) even under a high invalid rate, high input swing (0.21 standard deviation), and 7% salt noise in binary input, respectively, whereas the device variation has a trivial effect on the network.
Macrophages play a pivotal role in tissue fibrogenesis, which underlies the pathogenesis of many end-stage chronic inflammatory diseases. MicroRNAs are key regulators of immune cell functions, but ...their roles in macrophage's fibrogenesis have not been characterized. Here we show that IL-4 and IL-13 induce miR-142-5p and downregulate miR-130a-3p in macrophages; these changes sustain the profibrogenic effect of macrophages. In vitro, miR-142-5p mimic prolongs STAT6 phosphorylation by targeting its negative regulator, SOCS1. Blocking miR-130a relieves its inhibition of PPARγ, which coordinates STAT6 signalling. In vivo, inhibiting miR-142-5p and increasing miR-130a-3p expression with locked nucleic acid-modified oligonucleotides inhibits CCL4-induced liver fibrosis and bleomycin-induced lung fibrosis in mice. Furthermore, macrophages from the tissue samples of patients with liver cirrhosis and idiopathic pulmonary fibrosis display increased miR-142-5p and decreased miR-130a-3p expression. Therefore, miR-142-5p and miR-130a-3p regulate macrophage profibrogenic gene expression in chronic inflammation.
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•SCCPs and MCCPs in rubber track products and raw materials were analyzed.•SCCP in most of tracks and adhesives exceeded the Chinese standard limit.•Adhesives were the main ...contributors of CPs to the track products.•Human health and environment implications of CPs emitted from tracks were estimated.
Short- and medium-chain chlorinated paraffins (SCCPs and MCCPs) in commercial rubber track products and raw materials (rubber granules and adhesives) were investigated by two-dimensional gas chromatography with electron-capture negative-ionization mass spectrometry (GC × GC-ECNI-MS). The mean SCCP and MCCP concentrations in the rubber track products were 3.64 × 103 and 4.14 × 104 μg/g, respectively. The mean SCCP concentration in the products was significantly higher than those in the rubber granules (2.78 μg/g), but in the same order of magnitude as those in the adhesives (3.34 × 103 μg/g). The SCCP concentrations in almost half of the rubber track products and four fifths of the adhesives exceeded the limit (1.5 g/kg) set in Chinese standard GB 36246-2018. The dominant SCCP and MCCP congeners in the rubber track products were similar to those in the relevant adhesives but different from those in the paired granules. Principal component analysis and contribution calculations indicated that chlorinated paraffins (CPs) in adhesives could be the main sources of CPs in rubber track products. The high CP concentrations found in rubber track products are of special concern because of the relatively high exposures for children and negative effect on human health and environment.
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