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Xiao-Yi Song Yu-Hang Zhang Ping-Ping Sun Prof. Dr. Jun Gao Prof. Dr. Fa-Nian Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(25):5654-5661
Novel lithium–lanthanide (Ln: cerium and praseodymium) bimetallic coordination polymers with formulas C10H2LnLiO8 (Ln: Ce (CeLipma) and Pr (PrLipma)) and C10H3CeO8 (Cepma) were prepared through a simple hydrothermal method. The three compounds were characterized by means of FTIR spectroscopy, X-ray diffraction, single-crystal X-ray diffraction, SEM, TEM, and X-ray photoelectron spectroscopy. The results of structural refinement show that they belong to triclinic symmetry and P space group with cerium (or praseodymium) and lithium cations, forming coordination bonds to oxygen atoms from different pyromellitic acid molecules, and leading to the construction of 3D structures. It is interesting to note that the frameworks exclude any coordination water and lattice water. As an electrode material for lithium-ion batteries, CeLipma exhibits a maximum capacity of 800.5 mAh g−1 and a retention of 91.4 % after 50 cycles at a current density of 100 mA g−1. The favorable electrochemical properties of the lanthanide coordination polymers show potential application prospects in the field of electrode materials. 相似文献
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《Expositiones Mathematicae》2022,40(2):357-394
We give an informal exposition of pushforwards and orientations in generalized cohomology theories in the language of spectra. The whole note can be seen as an attempt at convincing the reader that Todd classes in Grothendieck–Hirzebruch–Riemann–Roch type formulas are not Devil’s appearances but rather that things just go in the most natural possible way. 相似文献
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《Indagationes Mathematicae》2022,33(6):1221-1235
In a recent paper (Temme, 2021) new asymptotic expansions are given for the Kummer functions and for large positive values of and , with fixed and special attention for the case . In this paper we extend the approach and also accept large values of . The new expansions are valid when at least one of the parameters , , or is large. We provide numerical tables to show the performance of the expansions. 相似文献
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S. Aleksanian N. Arakelian 《Journal of Contemporary Mathematical Analysis (Armenian Academy of Sciences)》2009,44(3):147-162
The paper discusses the best or optimal uniform approximation problem by entire functions on a closed angle Δ. This problem has been studied by M.V. Keldysch in [4], under the assumption that the functions ? subject to approximation are holomorphic in a larger angle containing Δ and there is no restriction on the growth of ? at infinity. In [8], the problem was investigated for a wider class of functions ? continuously complex differentiable on Δ, with sharper estimates on the growth of approximating entire functions, linked with the growth of ? on Δ and the differential properties of ? on the boundary of Δ. In this paper, we improve some of the results on entire approximation on angles, using new approximation ideas partially presented in [9] and [10]. 相似文献
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H. Sardon A. González M.J. Fernández-Berridi 《Journal of Macromolecular Science: Physics》2015,54(6):711-721
The oxygen barrier properties of films obtained from waterborne polyurethane/silica hybrid dispersions were analyzed. Two different types of polyurethanes were used, based on poly(propylene glycol) and poly(1,4-butylene adipate). Three different strategies were followed in the preparation of the hybrid dispersions. In the first type of materials (series 1), the inorganic part came exclusively from the covalent incorporation of trifunctional silane groups into the polymeric chains. The other two series contained, in addition to the trifunctional silane groups, tetrafunctional silane groups either physically blended (series 2) or “in situ” generated (series 3). Materials of series 1 showed an increase of the oxygen permeability coefficient with the silane content. However, the other two types of materials presented just the opposite dependence. In this latter case, the systems containing “in situ” generated silica (series 3) presented higher permeability coefficient values, probably because of the steric hindrance imposed by the polyurethane that gave rise to silica networks containing silanol groups and free volume holes. Moreover, lower permeability coefficient values were obtained when larger size particles were added. This fact could mean that the polyurethane/silica interface effects were not totally hindered even when the organic/inorganic phases were covalently bonded. 相似文献
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