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31.
Christian M. Schurz 《Journal of solid state chemistry》2010,183(10):2253-2260
In attempts to synthesize lanthanide(III) nitride iodides with the formula M2NI3 (M=La-Nd), moisture-sensitive single crystals of the first quaternary sodium lanthanide(III) nitride iodides NaM4N2I7 (orthorhombic, Pna21; Z=4; a=1391-1401, b=1086-1094, c=1186-1211 pm) could be obtained. The dominating structural features are chains of trans-edge linked [NM4]9+ tetrahedra, which run parallel to the polar 21-axis [001]. Between the chains, direct bonding via special iodide anions generates cages, in which isolated [NaI6]5- octahedra are embedded. The IR spectrum of NaLa4N2I7 recorded from 100 to 1000 cm-1 shows main bands at υ=337, 373 and 489 cm-1. With decreasing radii of the lanthanide trications these bands, which can be assigned as an influence of the vibrations of the condensed [NM4]9+ tetrahedra, are shifted toward higher frequencies for the NaM4N2I7 series (M=La-Nd), following the lanthanide contraction. 相似文献
32.
Yanqun Jiang Tao Xiong S.C.Wong Chi-Wang Shu Mengping Zhang Peng Zhang William H.K.Lam 《数学物理学报(B辑英文版)》2009,29(6):1541-1555
In this paper, a reactive dynamic user equilibrium model is extended to simulate two groups of pedestrians traveling on crossing paths in a continuous walking facility. Each group makes path choices to minimize the travel cost to its destination in a reactive manner based on instantaneous information. The model consists of a conservation law equation coupled with an Eikonal-type equation for each group. The velocity-density relationship of pedestrian movement is obtained via an experimental method. The model is solved using a finite volume method for the conservation law equation and a fast-marching method for the Eikonal-type equation on unstructured grids. The numerical results verify the rationality of the model and the validity of the numerical method. Based on this continuum model, a number of results, e.g., the formation of strips or moving clusters composed of pedestrians walking to the same destination, are also observed. 相似文献
33.
Prof. Hiroki Taniguchi Dr. Akihide Kuwabara Dr. Jungeun Kim Younghun Kim Dr. Hiroki Moriwake Prof. Sungwng Kim Takuya Hoshiyama Tsukasa Koyama Prof. Shigeo Mori Prof. Masaki Takata Prof. Hideo Hosono Prof. Yoshiyuki Inaguma Prof. Mitsuru Itoh 《Angewandte Chemie (International ed. in English)》2013,52(31):8088-8092
34.
For the heat equation backward in time
35.
Daniela Ferrarello Mario Pennisi 《International Journal of Mathematical Education in Science & Technology》2018,49(4):628-641
In this paper, we show some properties of centroids of geometric figures, such as triangles, quadrilaterals and tetrahedra. In particular, we will prove the properties by means of geometric transformations and by introducing extensions of triangles and quadrilaterals, i.e. by adding one, two or three new vertices to the figure. The study of these properties can be used, with profit, in a classroom activity supported by a dynamic geometry system. 相似文献
36.
A method is presented to generate and triangulate molecular surfaces rapidly. It is based on the ‘marching tetrahedra’ approach. The method is fast, simple and easy to implement. Our approach is not analytical in nature. Hence no special treatment is required for complications with singularity, degeneracy, or with self-intersecting re-entrant surfaces. A quick test for determining the solvent accessibility of a point in space forms an important part of the method. This test has potential use outside of the surface generation algorithm such as in molecular field analysis where the solvent accessibility of a point needs to be determined. The triangulated surface generated is suitable for molecular graphics display as well as boundary element continuum dielectric calculations. © 1998, Government of Canada. Exclusive worldwide publication rights in the article have been transferred to John Wiley & Sons, Inc. in perpetuity. J Comput Chem 19: 1268–1277, 1998 相似文献
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Hongping Wu Bingbing Zhang Hongwei Yu Zhanggui Hu Jiyang Wang Yicheng Wu P. Shiv Halasyamani 《Angewandte Chemie (International ed. in English)》2020,59(23):8922-8926
Discovering new deep‐ultraviolet (DUV) nonlinear optical (NLO) materials is currently a great challenge. The reported DUV NLO materials are almost exclusively borates or phosphates. Silicates—the largest constituent of the earth's crust—are excluded owing to their weak second harmonic generation (SHG) response. We report a silicate, Li2BaSiO4, with edge‐sharing LiO4–SiO4 tetrahedra that achieves the balance between a short UV absorption edge, below 190 nm, and a large SHG response, 2.8×KDP. The SHG intensity is the largest for silicates without second‐order Jahn–Teller cations, and exceeds that of non‐isomorphic Li2SrSiO4 by more than an order of magnitude. As such Li2BaSiO4 may be seen as a promising DUV‐UV NLO material. This research indicates that edge‐sharing tetrahedra is a new design parameter for discovering new DUV NLO materials. 相似文献