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Evidence of a gate-tunable Mott insulator in a trilayer graphene moiré superlattice
Chen, Guorui,Jiang, Lili,Wu, Shuang,Lyu, Bosai,Li, Hongyuan,Chittari, Bheema Lingam,Watanabe, Kenji,Taniguchi, Takashi,Shi, Zhiwen,Jung, Jeil,Zhang, Yuanbo,Wang, Feng NATURE PUBLISHING GROUP 2019 NATURE PHYSICS Vol.15 No.3
Emergence of Tertiary Dirac Points in Graphene Moiré Superlattices
Chen, Guorui,Sui, Mengqiao,Wang, Duoming,Wang, Shuopei,Jung, Jeil,Moon, Pilkyung,Adam, Shaffique,Watanabe, Kenji,Taniguchi, Takashi,Zhou, Shuyun,Koshino, Mikito,Zhang, Guangyu,Zhang, Yuanbo American Chemical Society 2017 NANO LETTERS Vol.17 No.6
<P>The electronic structure of a crystalline solid is largely determined by its lattice structure. Recent advances in van der Waals solids, artificial crystals with controlled stacking of two-dimensional (2D) atomic films, have enabled the creation of materials with novel electronic structures. In particular, stacking graphene on hexagonal boron nitride (hBN) introduces a moire superlattice that fundamentally modifies graphenes band structure and gives rise to secondary Dirac points (SDPs). Here we find that the formation of a moire superlattice in graphene on hBN yields new, unexpected consequences: a set of tertiary Dirac points (TDPs) emerge, which give rise to additional sets of Landau levels when the sample is subjected to an external magnetic field. Our observations hint at the formation of a hidden Kekule superstructure on top of the moire superlattice under appropriate carrier doping and magnetic fields.</P>
Heat Shock Factor 1 Is a Transcription Factor of Fas Gene
Shunmei E.,Yuanbo Zhao,Yunhong Huang,Kun Lai,Cha Chen,Jianming Zeng,Jiangying Zou 한국분자세포생물학회 2010 Molecules and cells Vol.29 No.5
In mammalian cells, stress-induced expression of heat shock protein is controlled by heat shock factor 1 (HSF1). However, HSF1 functions as a regulator of additional genes. In this study, we observed that heat treatment effectively induced expression of Fas. Using bioinformatics,a high affinity and functional HSF1-binding element within the -1996/-1985 oligonucleotide of the 5′-flanking region of the Fas gene was found, and was determined by electrophoretic mobility shift assay and chromatin immunoprecipitation assay. Exogenous expression of a constitutively activative HSF1, induced Fas gene transcription and protein synthesis in the absence of heat stress. Moreover, RNA interference-mediated HSF1 gene-silencing attenuated Fas expression in a heat-induced model. Our results suggested that HSF1 is an important transcription factor of Fas gene.
Lijuan Kong,Xiaoyu Chen,Yuanbo Du 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.17 No.5
In this study, the influence of coarse aggregate size and type on chloride penetration of concrete was investigated, and the grey correlation analysis was applied to find the key influencing factor. Furthermore, the proposed 6-10-1 artificial neural network (ANN) model was constructed, and performed under the MATLAB program. Training, testing and validation of the model stages were performed using 81 experiment data sets. The results show that the aggregate type has less effect on the concrete permeability, compared with the size effect. For concrete with a lower w/b, the coarse aggregate with a larger particle size should be chose, however, for concrete with a higher w/c, the aggregate with a grading of 5-20 mm is preferred, too large or too small aggregates are adverse to concrete chloride diffusivity. A new idea for the optimum selection of aggregate to prepare concrete with a low penetration is provided. Moreover, the ANN model predicted values are compared with actual test results, and the average relative error of prediction is found to be 5.62%. ANN procedure provides guidelines to select appropriate coarse aggregate for required chloride penetration of concrete and will reduce number of trial and error, save cost and time.
Yang, Jianqing,Zhou, Jianrong,Zhang, Lianjun,Tan, Jinhao,Jiang, Xingfen,Zhou, Jianjin,Zhou, Xiaojuan,Hou, Linjun,Song, Yushou,Sun, XinLi,Zhang, Quanhu,Sun, Zhijia,Chen, Yuanbo Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.7
The <sup>n</sup>MCP (Neutron sensitive microchannel plate) combined with advanced readout electronics is widely used in energy selective neutron imaging because of its good spatial and timing resolution. Neutron detection efficiency is a crucial parameter for the <sup>n</sup>MCP. In this paper, a mathematical model based on the oblique cylindrical channel and elliptical pore was established to calculate the neutron absorption probability, the escape probability of charged particles and overall detection efficiency of <sup>n</sup>MCP and analyze the effects of neutron incident position, pore diameter, wall thickness and bias angle. It was shown that when the doping concentration of the <sup>n</sup>MCP was 10 mol%, the thickness of <sup>n</sup>MCP was 0.6 mm, the detection efficiency could reach maximum value, about 24% for thermal neutrons if the pore diameter was 6 ㎛, the wall thickness was 2 ㎛ and the bias angle was 3 or 6°. The calculated results are of great significance for evaluating the detection efficiency of the <sup>n</sup>MCP. In a subsequent companion paper, the mathematical model would be extended to the case of the spatial resolution and detection efficiency optimization of the coating <sup>n</sup>MCP.
Gate-tunable phase transitions in thin flakes of 1T-TaS2.
Yu, Yijun,Yang, Fangyuan,Lu, Xiu Fang,Yan, Ya Jun,Cho, Yong-Heum,Ma, Liguo,Niu, Xiaohai,Kim, Sejoong,Son, Young-Woo,Feng, Donglai,Li, Shiyan,Cheong, Sang-Wook,Chen, Xian Hui,Zhang, Yuanbo Nature Pub. Group 2015 Nature nanotechnology Vol.10 No.3
<P>The ability to tune material properties using gating by electric fields is at the heart of modern electronic technology. It is also a driving force behind recent advances in two-dimensional systems, such as the observation of gate electric-field-induced superconductivity and metal-insulator transitions. Here, we describe an ionic field-effect transistor (termed an iFET), in which gate-controlled Li ion intercalation modulates the material properties of layered crystals of 1T-TaS2. The strong charge doping induced by the tunable ion intercalation alters the energetics of various charge-ordered states in 1T-TaS2 and produces a series of phase transitions in thin-flake samples with reduced dimensionality. We find that the charge-density wave states in 1T-TaS2 collapse in the two-dimensional limit at critical thicknesses. Meanwhile, at low temperatures, the ionic gating induces multiple phase transitions from Mott-insulator to metal in 1T-TaS2 thin flakes, with five orders of magnitude modulation in resistance, and superconductivity emerges in a textured charge-density wave state induced by ionic gating. Our method of gate-controlled intercalation opens up possibilities in searching for novel states of matter in the extreme charge-carrier-concentration limit.</P>