17,407 research outputs found
Xiang ding gu wen ping zhu quan ji
No full text劉豫菴鑑定 ; [過珙, 黃越評選].Liu Yu'an jian ding ; [Guo Gong, Huang Yue ping xuan]
Self-passivation leads to semiconducting edges of black phosphorene
No full textThe edges of black phosphorene (BP) have been extensively explored. The previous experimental observations that all the BP edges are semiconducting implies that the as-cut edges of BP tend to be reconstructed. Here we present a global structural search of three typical BP edges, namely armchair, zigzag and zigzag-1 edges. It is found that all the three pristine edges are metastable, and all of them can be quickly self-passivated by (i) forming P=P double bonds (one r and one p bond), (ii) reconstructing new polygonal rings will all P atoms bonded with three sp3 bonds or (iii) forming a special P(2)-P(4) configuration with a two-coordinated P atom accommodating two lone pair electrons and one four-coordinated P atom without lone pair electrons. Highly different from the pristine edges, all these highly stable reconstructed edges are semiconducting. This study showed that the reconstruction of the edges of a 2D material, just like the surfaces of a 3D crystal, must be considered for both fundamental studies and practical applications. Besides BP, this study also sheds light on the structures and properties of the edges of many other 2D materials.11Nsciescopu
Mechanism of 2D Materials??? Seamless Coalescence on a Liquid Substrate
No full textThe seamless coalescence of parallelly aligned 2D materials is the primary route toward the synthesis of wafer-scale single crystals (WSSCs) of 2D materials. The epitaxial growth of various 2D materials on a single-crystal substrate, which is an essential condition of the seamless coalescence approach, has been extensively explored in previous studies. Here, by using hexagonal boron nitride (hBN) growth on a liquid gold surface as an example, we demonstrate that growth of WSSCs of 2D materials via the seamless coalescence of self-aligned 2D islands on a liquid substrate is possible. Here we show that, in the presence of hydrogen, all the hBN edges tend to be hydrogen terminated and the coalescence of hBN islands occurs only if their crystallographic lattices of neighboring hBN islands are aligned parallelly. The mechanism of hBN self-alignment revealed in this study implies that, under the optimum experimental condition, the seamless coalescence of 2D materials on a liquid substrate is possible and thus provides guidance for synthesizing WSSCs of various 2D materials by using liquid phase substrates
Mechanism of MoS2 Growth on a Au(111) Surface: An Ab Initio Molecular Dynamics Study
No full textChemical vapor deposition (CVD) of transition-metal dichalcogenide (TMD) thin films, such as MoS2, on a gold (Au) surface has been regarded as one of the most promising approaches for the mass production of high-quality TMD thin films. However, the mechanism of TMD CVD growth on a gold surface remains a mystery, and many experimental observations, such as the surface chemistry during the initial stage of TMD growth and the formation of T-phase MoS2 on a Au surface, remain unclear. In this study, we systematically explored the initial stage of MoS2CVD growth on a Au(111) surface by using density functional theory-based molecular dynamics simulations. Some critical steps of MoS2 growth, such as the sulfidation of MoO3, the passivation of the Au(111) surface in the S-rich environment, and the lifting of Mo atoms from the Au substrate to form stable MoS2 nuclei, have been revealed in our atomic simulations. The theoretically predicted most stable T-phase small MoS2 clusters agree well with the previous experimental observations. Therefore, with an increase in the size of MoS2, a phase transition from the T phase to the H phase is essential for the growth of highly stable H-phase MoS2 films. This study greatly deepens our understanding of the mechanism of TMD CVD growth on a Au surface and provides guidance for the controllable CVD synthesis of various TMDs
The politics of fashion: perceptions of power in female clothing and ornamentation as reflected in the sixteenth-century Chinese novel Jin Ping Mei
No full textThis thesis examines issues of female power and influence in sixteenth-century China focusing on how women and their roles were perceived in the changing social environment of the mid-late Ming dynasty. Using aspects of a New Historicist approach, information from contemporary literary and historical sources are analysed alongside each other. With its emphasis on the lives of women and preoccupation with the description of material objects, the late Ming novel Jin Ping Mei forms an important element in the thesis. China in the sixteenth century saw expanding urbanisation, the emergence of a new wealthy merchant class, increasing visibility of women and a questioning of traditional morality. Fashion consciousness, as one of the most conspicuous aspects of the new material culture, is a possible indicator of these trends. Traditional Western theories contend that fashion began in the particular context of Renaissance Europe. However, this study argues that a similar fashion awareness existed in China too, and was manifested in a competitive striving for social status, in this case specifically among women. In contrast to previous studies which downplayed the impact women had on defining traditional Chinese culture, this thesis demonstrates how women and their sartorial choices began to redefine the boundaries of material culture, influencing literati discourse which, in turn, re- influenced female behaviour
Primulina cataractarum sp. nov. (Gesneriaceae) from limestone landform in Southern Hunan, China
No full textDing, Cong, Liu, Ang, Yu, Xun-Lin, Zhang, Chun-Ping (2021): Primulina cataractarum sp. nov. (Gesneriaceae) from limestone landform in Southern Hunan, China. Phytotaxa 511 (1): 51-64, DOI: 10.11646/phytotaxa.511.1.4, URL: http://dx.doi.org/10.11646/phytotaxa.511.1.
Entropy solutions for a hydrodynamic model for semiconductors
No full textWe investigate the Cauchy problem for a hydrodynamic model for semiconductors. A theorem on existence of global weak solutions with large initial data is obtained by using the fractional-step Lax-Friedrichs scheme and the Godunov schem
Clues, flow channels, and cognitive states: an exploratory study of customer experiences with e-brokerage services
No full textPeer reviewe
Qi sheng fang lue.
No full textCase title.On double leaves, oriental style, in cases.v. 1-420. Qin ding jiao ping Yue fei fang lue 420 juan -- v. 421-741. Qin ding jiao ping Nian fei fang lue 320 juan -- v. 742-792. Qin ding ping ding Yunnan Hui fei fang lue 50 juan -- v. 793-832. Qin ding ping ding Guizhou Miao fei ji lue 40 juan -- v. 833-1154. Qin ding ping ding Shan Gan Xinjiang Hui fei fang lue 320 juan.Mode of access: Internet
Atomically Sharp, Closed Bilayer Phosphorene Edges by Self-Passivation
No full textTwo-dimensional (2D) crystals' edge structures not only influence their
overall properties but also dictate their formation due to edge-mediated
synthesis and etching processes. Edges must be carefully examined because they
often display complex, unexpected features at the atomic scale, such as
reconstruction, functionalization, and uncontrolled contamination. Here, we
examine atomic-scale edge structures and uncover reconstruction behavior in
bilayer phosphorene. We use in situ transmission electron microscopy (TEM) of
phosphorene/graphene specimens at elevated temperatures to minimize surface
contamination and reduce e-beam damage, allowing us to observe intrinsic edge
configurations. Bilayer zigzag (ZZ) edge was found the most stable edge
configuration under e-beam irradiation. Through first-principles calculations
and TEM image analysis under various tilting and defocus conditions, we find
that bilayer ZZ edges undergo edge reconstruction and so acquire closed,
self-passivated edge configurations. The extremely low formation energy of the
closed bilayer ZZ edge and its high stability against e-beam irradiation are
confirmed by first-principles calculations. Moreover, we fabricate bilayer
phosphorene nanoribbons with atomically-sharp closed ZZ edges. The identified
bilayer ZZ edges will aid in the fundamental understanding of the synthesis,
degradation, reconstruction, and applications of phosphorene and related
structures.Comment: 22 pages, 5 figure
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