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1.
Cheng  Hongmei  Fang  Qinhe  Xia  Yang 《Applications of Mathematics》2022,67(5):615-632
Applications of Mathematics - We focus on the free boundary problems for a Leslie-Gower predator-prey model with radial symmetry in a higher dimensional environment that is initially well populated...  相似文献   
2.
Adsorptive separation of C2H6 from C2H4 by adsorbents is an energy-efficient and promising method to boost the polymer grades C2H4 production. However, that C2H6 and C2H4 display very similar physical properties, making their separation extremely challenging. In this work, by regulating the pore environment in a family of chitosan-based carbon materials (C-CTS-1, C-CTS-2, C-CTS-4, and C-CTS-6)- we target ultrahigh C2H6 uptake and C2H6/C2H4 separation, which exceeds most benchmark carbon materials. Explicitly, the C2H6 uptake of C-CTS-2 (166 cm3/g at 100 kPa and 298 K) has the second-highest adsorption capacity among all the porous materials. In addition, C-CTS-2 gives C2H6/C2H4 selectivity of 1.75 toward a 1:15 mixture of C2H6/C2H4. Notably, the adsorption enthalpies for C2H6 in C-CTS-2 are low (21.3 kJ/mol), which will facilitate regeneration in mild conditions. Furthermore, C2H6/C2H4 separation performance was confirmed by binary breakthrough experiments. Under different ethane/ethylene ratios, C-CTS-X extracts a low ethane concentration from an ethane/ethylene mixture and produces high-purity C2H4 in one step. Spectroscopic measurement and diffraction analysis provide critical insight into the adsorption/separation mechanism. The nitrogen functional groups on the surface play a vital role in improving C2H6/C2H4 selectivity, and the adsorption capacities depend on the pore size and micropore volume. Moreover, these robust porous materials exhibit outstanding stability (up to 800 °C) and can be easily prepared on a large scale (kg) at a low cost (~$26 per kg), which is very significant for potential industrial applications.  相似文献   
3.
Central European Journal of Operations Research - Environmental efficiency should not be treated independently of production efficiency. Several studies have demonstrated that lean management can...  相似文献   
4.
Lin  Hui-Min  Mu  Chao  Li  Ao  Liu  Xu-Feng  Li  Yu-Long  Jiang  Zhong-Qing  Wu  Hong-Ke 《Transition Metal Chemistry》2019,44(5):491-498
Transition Metal Chemistry - In this paper, four diiron toluene-3,4-dithiolate complexes with phosphine ligands were synthesized and characterized. Treatment of complex...  相似文献   
5.
Separation of minor compounds especially with similar polarities and structures from complex samples is a challenging work. In the present study, an efficient method was successfully established by macroporous resin column chromatography, medium‐pressure liquid chromatography, and high‐speed countercurrent chromatography for separation of four minor flavonoids from barley seedlings. Macroporous resin column chromatography and medium‐pressure liquid chromatography were used for enrichment of these four flavonoids. High‐pressure liquid chromatography analysis showed the total content of these four flavonoids increased from 2.2% in the crude extract to 95.3% in the medium‐pressure liquid chromatography fraction. It was indicated that the combination of macroporous resin column chromatography and medium‐pressure liquid chromatography could be a practicable strategy for enrichment of minor compounds from complex sample. Then, high‐speed countercurrent chromatography was employed for separation of these four flavonoids using ethyl acetate/n‐butanol/water (0.1% glacial acetic acid) (4:1:5, v/v/v) as solvent system. As a result, four flavonoids including two isomers with purities higher than 98% were obtained. Interestingly, two flavonoids existing in one high‐pressure liquid chromatography peak were also successfully separated. All these indicated high‐speed countercurrent chromatography had great potential for separation of compounds with similar structures and polarities. This study provides a reference for efficient enrichment and separation of minor compounds from complex sample.  相似文献   
6.
Wang  Yao  Cui  Jiewu  Wang  Yan  Yu  Dongbo  Cheng  Sheng  Zheng  Hongmei  Shu  Xia  Zhang  Yong  Wu  Yucheng 《Journal of Solid State Electrochemistry》2019,23(1):135-142
Journal of Solid State Electrochemistry - Substrate materials play a significant role in the improvement of electrochemical biosensors. In the present work, NiO nanoflake arrays were fully and...  相似文献   
7.
A simple and efficient chemical method was developed to graft directly carbon nanofibers (CNFs) onto carbon fiber (CF) surface to construct a CF‐CNF hierarchical reinforcing structure. The grafted CF reinforcements via covalent ester linkage at low temperature without any usage of dendrimer or catalyst was investigated by FTIR, X‐ray photoelectron spectroscopy, Raman, scanning electron microscopy, atomic force microscopy, dynamic contact angle analysis, and single fiber tensile testing. The results indicated that the CNFs with high density could effectively increase the polarity, wettability, and roughness of the CF surface. Simultaneous enhancements of the interfacial shear strength, flexural strength, and dynamic mechanical properties as well as the tensile strength of CFs were achieved, for an increase of 75.8%, 21.9%, 21.7%, and 0.5%, respectively. We believe the facile and effective method may provide a novel and promising interface design strategy for next‐generation advanced composite structures.  相似文献   
8.
Spherical fullerenes offer noteworthy structures usually involving six- and five-membered faces, with application in technological issues. In this sense, cavernous spherical-like structures bearing larger holes provide interesting examples for further understanding of structure-properties relationship. Here, we explored the magnetic response of a proposed cavernous nitride fullerene, C24N24, which has a Oh-symmetry with six N4-macrocyclic and eight 1,3,5-triazine faces displaying 48-π electrons. C24N24 exhibits a local aromatic behavior owing to the contrasting antiaromatic response of the N4-macrocyclic faces and the aromatic character of the 1,3,5-triazine faces. Thus, the overall structure is ascribed as a local aromatic species, where the triazine faces exhibit the characteristic shielding cone for aromatic rings. Furthermore, the constructive combination of local shielding cones in C24N24 delivers a related shielding-cone response, as expected for a perfect aromatic cage. Hence, the local aromatic/nonaromatic/antiaromatic sections exhibit an additive or subtractive interaction, leading to a characteristic response inherent to the nature of the spherical cage. We expect that further study of the interplay between different aromatic and antiaromatic faces in fullerene-like cages can deliver interesting pseudo-aromatic or pseudo-antiaromatic spherical species.  相似文献   
9.
10.
Based on detailed bonding analyses on the fluxional behaviors of planar B19, tubular Ta@B20, and cage-like B39, we propose the concept of fluxional bonds in boron nanoclusters as an extension of the classical localized bonds and delocalized bonds in chemistry. © 2018 Wiley Periodicals, Inc.  相似文献   
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