Pseudocapacitive Lithium Storage of Cauliflower-Like CoFe2O4 for Low-Temperature Battery Operation

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.     

Fabrication of a Novel Electrochemical Sensor for Determination of Riboflavin in Different Drink Real Samples

Russian Journal of Electrochemistry - In the present study an electrochemical sensor has been produced for measuring riboflavin with high sensitivity and selectivity. Deferential pulse technique...     

Biological Activities Evaluation of Enantiopure Isoxazolidine Derivatives: In Vitro,In Vivo and In Silico Studies

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...     

Empirical Interpolation Decomposition

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.

     

Synthesis,characterization and antibacterial activity of palladium(II) bromide complexes of thioamides; X-ray structure of [Pd(tetramethylthiourea)<Subscript>4</Subscript>]Br<Subscript>2</Subscript>

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.     

Ensemble of a subset of <Emphasis Type="Italic">k</Emphasis>NN classifiers

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.     

Xanthine oxidase inhibiting flavonol glycoside from Amberboa ramosa

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.     

Exploring Amantadine Derivatives as Urease Inhibitors: Molecular Docking and Structure–Activity Relationship (SAR) Studies

This article describes the design and synthesis of a series of novel amantadine-thiourea conjugates (3a–j) as Jack bean urease inhibitors. The synthesized hybrids were assayed for their in vitro urease inhibition. Accordingly, N-(adamantan-1-ylcarbamothioyl)octanamide (3j) possessing a 7-carbon alkyl chain showed excellent activity with IC₅₀ value 0.0085 ± 0.0011 µM indicating that the long alkyl chain plays a vital role in enzyme inhibition. Whilst N-(adamantan-1-ylcarbamothioyl)-2-chlorobenzamide (3g) possessing a 2-chlorophenyl substitution was the next most efficient compound belonging to the aryl series with IC₅₀ value of 0.0087 ± 0.001 µM. The kinetic mechanism analyzed by Lineweaver–Burk plots revealed the non-competitive mode of inhibition for compound 3j. Moreover, in silico molecular docking against target protein (PDBID 4H9M) indicated that most of the synthesized compounds exhibit good binding affinity with protein. The compound 3j forms two hydrogen bonds with amino acid residue VAL391 having a binding distance of 1.858 Å and 2.240 Å. The interaction of 3j with amino acid residue located outside the catalytic site showed its non-competitive mode of inhibition. Based upon these results, it is anticipated that compound 3j may serve as a lead structure for the design of more potent urease inhibitors.     

Synthesis and antimicrobial activity of new functionalized derivatives of [1,2,4]triazolo[4,3‐a]pyrimidin‐5(1H)‐one

New functionalized 1,7‐diaryl‐6‐cyano‐1,2,4‐triazolo[4,3‐a]pyrimidin‐5(1H)‐one derivatives ( 5a–j ) were synthesized via reaction of 5‐cyano‐6‐phenyl‐2‐thiouracil 1 with the respective hydrazonoyl halides 2a–j and their biological activity was evaluated. The mechanism and the regioselectivity of the studied reactions are discussed. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:393–398, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20311