In this work, the photocatalytic activity of the synthesized graphene oxide (GO)‐Fe3O4/TiO2 mesoporous photocatalysts was evaluated using chlorpyrifos (CP) as a contaminant. The nano‐photocatalyst was characterized by X‐ray diffraction, field emission scanning electron microscopy with energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, and specific surface area by the Brunauer–Emmett–Teller method. Using visible light, the GO‐Fe3O4/TiO2 mesoporous photocatalyst was investigated on the degradation of CP pesticide. The GO‐Fe3O4/TiO2 photocatalyst displayed a good photocatalytic activity, which was achieving 97% of CP degradation after 60 min. Finally, experiments were performed to evaluate GO‐Fe3O4/TiO2 mesoporous nanocatalyst activity on repeated applications; after several uses, its photocatalytic activity was retained, which indicated stability. 相似文献
Binary transition-metal oxides (BTMOs) with hierarchical micro–nano-structures have attracted great interest as potential anode materials for lithium-ion batteries (LIBs). Herein, we report the fabrication of hierarchical cauliflower-like CoFe2O4 (cl-CoFe2O4) via a facile room-temperature co-precipitation method followed by post-synthetic annealing. The obtained cauliflower structure is constructed by the assembly of microrods, which themselves are composed of small nanoparticles. Such hierarchical micro–nano-structure can promote fast ion transport and stable electrode–electrolyte interfaces. As a result, the cl-CoFe2O4 can deliver a high specific capacity (1019.9 mAh g−1 at 0.1 A g−1), excellent rate capability (626.0 mAh g−1 at 5 A g−1), and good cyclability (675.4 mAh g−1 at 4 A g−1 for over 400 cycles) as an anode material for LIBs. Even at low temperatures of 0 °C and −25 °C, the cl-CoFe2O4 anode can deliver high capacities of 907.5 and 664.5 mAh g−1 at 100 mA g−1, respectively, indicating its wide operating temperature. More importantly, the full-cell assembled with a commercial LiFePO4 cathode exhibits a high rate performance (214.2 mAh g−1 at 5000 mA g−1) and an impressive cycling performance (612.7 mAh g−1 over 140 cycles at 300 mA g−1) in the voltage range of 0.5–3.6 V. Kinetic analysis reveals that the electrochemical performance of cl-CoFe2O4 is dominated by pseudocapacitive behavior, leading to fast Li+ insertion/extraction and good cycling life. 相似文献
Applied Biochemistry and Biotechnology - A series of enantiopure isoxazolidines (3a–c) were synthesized by 1,3-dipolar cycloaddition between a (−)-menthone-derived nitrone and various... 相似文献
The Kantorovich metric provides a way of measuring the distance between two Borel probability measures on a metric space. This metric has a broad range of applications from bioinformatics to image processing, and is commonly linked to the optimal transport problem in computer science (Deng and Du in Electron. Notes Theor. Comput. Sci. 253: 73–82, 2009; Villani in Optimal Transport: Old and New, Grundlehren der mathematischen Wissenschaften, vol. 338, 2009). Noteworthy to this paper will be the role of the Kantorovich metric in the study of iterated function systems, which are families of contractive mappings on a complete metric space. When the underlying metric space is compact, it is well known that the space of Borel probability measures on this metric space, equipped with the Kantorovich metric, constitutes a compact, and thus complete metric space. In previous work, we generalized the Kantorovich metric to operator-valued measures for a compact underlying metric space, and applied this generalized metric to the setting of iterated function systems (Davison in Acta Appl. Math., 2014, https://doi.org/10.1007/s10440-014-9976-y; Generalizing the Kantorovich Metric to Projection-Valued Measures: With an Application to Iterated Function Systems, 2015; Acta Appl. Math., 2018, https://doi.org/10.1007/s10440-018-0161-6). We note that the work of P. Jorgensen, K. Shuman, and K. Kornelson provided the framework for our application to this setting (Jorgensen in Adv. Appl. Math. 34(3):561–590, 2005; Jorgenson et al. in J. Math. Phys. 48(8):083511, 2007; Jorgensen in Operator Theory, Operator Algebras, and Applications, Contemp. Math., vol. 414, pp. 13–26, 2006). The situation when the underlying metric space is complete, but not necessarily compact, has been studied by A. Kravchenko (Sib. Math. J. 47(1), 68–76, 2006). In this paper, we extend the results of Kravchenko to the generalized Kantorovich metric on operator-valued measures.
Position-dependent-mass systems are of great importance in many physical situations,such as the transport of charge carriers in semiconductors with non-uniform composition and in the theory of many-body interactions in condensed matter.Here we investigate,numerically and analytically,the phenomenon of fractional revivals in such systems,which is a generic characteristic manifested by the wave-packet evolution in bounded Hamiltonian systems.Identifying the fractional revivals using specific probe... 相似文献
Palladium(II) bromide complexes of thioamides having the general formulae [PdL2Br2] and [PdL4]Br2 where L = Thiourea (Tu), Methylthiourea (Metu), Dimethylthiourea (Dmtu), Tetramethylthiourea (Tmtu), Imidazolidine-2-thione
(Imt), Mercaptopyridine (Mpy), Mercaptopyrimidine (Mpm) and Thionicotinamide (Tna) were prepared by reacting K2[PdCl4] with KBr and the corresponding thioamides. The complexes were characterized by elemental analysis, IR and NMR spectroscopy,
and one of them, [Pd(Tmtu)4]Br2 (1) by X-ray crystallography. The crystal structure of 1 shows a square-planar coordination environment around the Pd(II) atoms with the average cis and trans S–Pd–S bond angles of 90.0° and 180.0°, respectively. The synthesized complexes were screened for antibacterial effects,
and the results showed that the complexes exhibit significant activities against both gram positive and gram negative bacteria. 相似文献
This Note examines the probabilistic structure of a GARCH-type stochastic difference equation with periodically time-varying parameters. We propose necessary and sufficient conditions ensuring the existence of stationary solutions, geometrically ergodic (in the periodic sense) and having finite higher-order moments. To cite this article: A. Bibi, A. Aknouche, C. R. Acad. Sci. Paris, Ser. I 347 (2009).相似文献
Combining multiple classifiers, known as ensemble methods, can give substantial improvement in prediction performance of learning algorithms especially in the presence of non-informative features in the data sets. We propose an ensemble of subset of kNN classifiers, ESkNN, for classification task in two steps. Firstly, we choose classifiers based upon their individual performance using the out-of-sample accuracy. The selected classifiers are then combined sequentially starting from the best model and assessed for collective performance on a validation data set. We use bench mark data sets with their original and some added non-informative features for the evaluation of our method. The results are compared with usual kNN, bagged kNN, random kNN, multiple feature subset method, random forest and support vector machines. Our experimental comparisons on benchmark classification problems and simulated data sets reveal that the proposed ensemble gives better classification performance than the usual kNN and its ensembles, and performs comparable to random forest and support vector machines. 相似文献
A new flavonol glycoside (1) has been isolated from the ethyl acetate soluble fraction of Amberboa ramosa and assigned the structure 5,7,4'-trihydroxy-3,8-dimethoxylflavone 5-O-beta-D-gluco-pyranoside (1). In addition, 6,4'-dihydroxy-3,5,7-trimethoxyflavone (2), 5,7-dihydroxy-4'-methoxyflavone (3) and (23R)-5alpha-cycloart-24-ene-3beta,21,23-triol (4) have also been reported for the first time from this species. The structures were deduced on the basis of 1D and 2D NMR techniques. The compounds 1-3 displayed weak to moderate inhibition against the xanthine oxidase enzyme. 相似文献