Electronic, optical and transport properties of van der Waals Transition-metal Dichalcogenides Heterostructures: A First-principle Study

Two-dimensional (2D) transition-metal dichalcogenide (TMD) MX$_2$ (M = Mo, W; X= S, Se, Te) possess unique properties and novel applications. In this work, we perform first-principles calculations on the van der Waals (vdW) stacked MX$_2$ heterostructures to investigate their electronic, optical and transport properties systematically. We perform the so-called Anderson's rule to classify the heterostructures by providing the scheme of the construction of energy band diagrams for the heterostructure consisting of two semiconductor materials. For most of the MX$_2$ heterostructures, the conduction band maximum (CBM) and valence band minimum (VBM) reside in two separate semiconductors, forming type II band structure, thus the electron-holes pairs are spatially separated. We also find strong interlayer coupling at $\Gamma$ point after forming MX$_2$ heterostructures, even leading to the indirect band gap. While the band structure near $K$ point remain as the independent monolayer. The carrier mobilities of MX$_2$ heterostructures depend on three decisive factors, elastic modulus, effective mass and deformation potential constant, which are discussed and contrasted with those of monolayer MX$_2$, respectively.Comment: 7 figure

Key Problems and Techniques of Geophysical Exploration in Underground Salt Cavern for Compressed Air Energy Storage

[Introduction] The world′s first 300 MW compressed air energy storage (CAES) power station is in Yingcheng City, Hubei Province, China. The station uses the existing underground salt cavern which is the best of its tight sealing and high capacity as gas storage, The parameters of the underground salt cavern, such as the underground salt cavity volume, shape, and depth, are crucial for the construction feasibility of the CAES power station. [Method] Based on the Yingcheng CAES power station project practice, this paper analyzed and summarized the many key problems and processing techniques of the high precision 3D seismic geophysical exploration methods in detecting deep salt cavity shapes. [Result] For the purpose of proving the occurrence characteristics of existing underground salt cavity, the 3D seismic geophysical exploration observation system shall be designed to meet the high resolution requirements, and the CDP gridding shall have an accuracy of at least 5 m×5 m, in order to make sure the fold number of the target area is more than 30 times. It is indispensable to improve the salt cavern 3D seismic data quality by conducting static correction and pre-stack denoising. Consistency processing technique is used and accurate velocity field is constructed according to different excitation and receiving conditions to realize precise depth homing. We find the track integral attribute, reflection strength attribute and sweetness attribute have an obvious advantage in identifying salt cavern space distribution, while edge detection attribute has a strong indication on cavity border depiction and connectivity. [Conclusion] Through research on key techniques of data processing and interpretation in geophysical exploration, the salt cavity parameters such as volume, shape, and depth are clearly detected to provide detailed and reliable data support for the salt cavern project. Research on the key problems and techniques of the 3D seismic geophysical exploration for the salt cavern can provide reference to the construction of large-scale CAES power stations of underground salt cavern type

Identification of BC005512 as a DNA Damage Responsive Murine Endogenous Retrovirus of GLN Family Involved in Cell Growth Regulation

Genotoxicity assessment is of great significance in drug safety evaluation, and microarray is a useful tool widely used to identify genotoxic stress responsive genes. In the present work, by using oligonucleotide microarray in an in vivo model, we identified an unknown gene BC005512 (abbreviated as BC, official full name: cDNA sequence BC005512), whose expression in mouse liver was specifically induced by seven well-known genotoxins (GTXs), but not by non-genotoxins (NGTXs). Bioinformatics revealed that BC was a member of the GLN family of murine endogenous retrovirus (ERV). However, the relationship to genotoxicity and the cellular function of GLN are largely unknown. Using NIH/3T3 cells as an in vitro model system and quantitative real-time PCR, BC expression was specifically induced by another seven GTXs, covering diverse genotoxicity mechanisms. Additionally, dose-response and linear regression analysis showed that expression level of BC in NIH/3T3 cells strongly correlated with DNA damage, measured using the alkaline comet assay,. While in p53 deficient L5178Y cells, GTXs could not induce BC expression. Further functional studies using RNA interference revealed that down-regulation of BC expression induced G1/S phase arrest, inhibited cell proliferation and thus suppressed cell growth in NIH/3T3 cells. Together, our results provide the first evidence that BC005512, a member from GLN family of murine ERV, was responsive to DNA damage and involved in cell growth regulation. These findings could be of great value in genotoxicity predictions and contribute to a deeper understanding of GLN biological functions

An atypical form of retinitis pigmentosa: A case report

Key Clinical Message This case contributes to the new knowledge of unilateral pericentral RP. Multimodal imaging provides valuable information to better understand the disease. The development is significantly slow and defines a better clinical course than typical RP. Pericentral RP presents with unremarkable night blindness, which can be easily misdiagnosed by ophthalmologists. Abstract Unilateral pericentral retinitis pigmentosa (RP) is a rare, atypical, mild form of RP that affects the pericentral retina close to the vascular arcades and tends to spare the far‐peripheral retina in one eye, while the fellow eye remains completely unaffected. A 71‐year‐old Chinese woman presented with blurred vision in her right eye for several decades, however, her left eye was unaffected. Fundus photography revealed bone‐spicule pigmentation located at the pericentral retina of her right eye. Spectral‐domain optical coherence tomography revealed significant atrophy of the outer retina and retinal pigment epithelium, and an evident absence of the ellipsoid zone in the right eye. The visual field showed a wide‐range paracentral scotoma in the right eye. The full‐field electroretinogram demonstrated subnormal amplitudes of dark and light adaption in the right eye. No significant changes were observed during a further 5‐year follow‐up. Multimodal imaging provides valuable information to better understand unilateral pericentral RP. The development of unilateral pericentral RP is significantly slow and defines a better clinical course than the typical RP. Pericentral RP presents with slight visual reduction and unremarkable night blindness, which can be easily misdiagnosis by ophthalmologists. Reasonable prevention measures, screening methods, and timely diagnosis are beneficial for RP patients

Reliability Uncertainty Analysis Method for Aircraft Electrical Power System Design Based on Variance Decomposition

As a safety critical system, affected by cognitive uncertainty and flight environment variability, aircraft electrical power system proves highly uncertain in its failure occurrence and consequences. However, there are few studies on how to reduce the uncertainty in the system design stage, which is of great significance for shortening the development cycle and ensuring flight safety during the operation phrase. For this reason, based on the variance decomposition theory, this paper proposes an importance measure index of the influence of component failure rate uncertainty on the uncertainty of power supply reliability (system reliability). Furthermore, an algorithm to calculate the measure index is proposed by combining with the minimum path set and Monte Carlo simulation method. Finally, the proposed method is applied to a typical series-parallel system and an aircraft electrical power system, and a criteria named as “quantity and degree optimization criteria” is drawn from the case study. Results demonstrate that the proposed method indeed realizes the measurement of the contribution degree of component failure rate uncertainty to system reliability uncertainty, and combined with the criteria, proper solutions can be quickly determined to reduce system reliability uncertainty, which can be a theoretical guidance for aircraft electrical power system reliability design

Reliability Evaluation for Aviation Electric Power System in Consideration of Uncertainty

With the rapid development of more electric aircraft (MEA) in recent years, the aviation electric power system (AEPS) has played an increasingly important role in safe flight. However, as a highly reliable system, because of its complicated flight conditions and architecture, it often proves significant uncertainty in its failure occurrence and consequence. Thus, more and more stakeholders, e.g., passengers, aviation administration departments, are dissatisfied with the traditional system reliability analysis, in which failure uncertainty is not considered and system reliability probability is a constant value at a given time. To overcome this disadvantage, we propose a new methodology in the AEPS reliability evaluation. First, we perform a random sampling from the probability distributions of components’ failure rates and compute the system reliability at each sample point; after that, we use variance, confidence interval, and probability density function to quantify the uncertainty of system reliability. Finally, we perform the new method on a series–parallel system and an AEPS. The results show that the power supply reliability of AEPS is uncertain and the uncertainty varies with system time even though the uncertainty of each component’s failure is quite small; therefore it is necessary to quantify system uncertainty for safer flight, and our proposed method could be an effective way to accomplish this quantization task