Novel simple fluorescent sensor for nickel ions

A novel pyrazoline with benzimidazole substituent was conveniently synthesized, starting from a chalcone and 2-hydrazinylpyridine. The addition of Ni²⁺ to ethanol solution of the synthesized pyrazoline resulted in a rapid color change from blue to green which allows the selective detection of Ni²⁺ ion over a great number of other metal ions. The association constant for the 1:1 complex was determined to be 2.72 × 10⁷ M^?1.     

Simultaneous determination of trimethylamine,formaldehyde and benzene via the cataluminescence of In<Subscript>3</Subscript>LaTi<Subscript>2</Subscript>O<Subscript>10</Subscript> nanoparticles

The authors describe a cataluminescence (CTL) based sensing method via signals generated at the surface of In₃LaTi₂O₁₀ nanoparticles for simultaneous determination of trimethylamine, formaldehyde and benzene in air. The analytical wavelengths are 340 nm, 440 nm and 600 nm, and the best surface temperature of the catalytic material is 275 °C. The limits of detection of this method are 0.3 mg?m^?3 for trimethylamine, 0.07 mg?m^?3 for formaldehyde, and 0.2 mg?m^?3 for benzene. The linear ranges of CTL intensity versus gas/vapor concentration are from 1.0 to 65.1 mg?m^?3 for trimethylamine, from 0.2 to 72.5 mg?m^?3 for formaldehyde, and from 0.5 to 77.5 mg?m^?3 for benzene. The recoveries after testing 10 standard samples ranged from 98.1% to 102.6% for trimethylamine, from 98.1% to 102.6% for formaldehyde, and from 97.7% to 103.8% for benzene. Gaseous ammonia, acetaldehyde, toluene, ethylbenzene, ethanol, sulfur dioxide and carbon dioxide do not interfere. The relative deviation of the CTL signals after 200 h of continuous detection of trimethylamine, formaldehyde and benzene is <3%.

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Graphical abstract Schematic of a cataluminescence (CTL) based method for simultaneous determination of trimethylamine (TMA), formaldehyde (HCHO) and benzene (C₆H₆) in air. The linear ranges of CTL intensity versus gas/vapor concentration are from 1.0 to 65.1 mg?m^?3 for TMA, from 0.2 to 72.5 mg?m^?3 for HCHO, and from 0.5 to 77.5 mg?m^?3 for C₆H₆.

     

Unraveling the Mechanism for the Sharp‐Tip Enhanced Electrocatalytic Carbon Dioxide Reduction: The Kinetics Decide

The electrocatalytic reduction reaction of carbon dioxide can be significantly enhanced by the use of a sharp‐tip electrode. However, the experimentally observed rate enhancement is many orders of magnitudes smaller than what would be expected from an energetic point of view. The kinetics of this tip‐enhanced reaction are shown to play a decisive role, and a novel reaction‐diffusion kinetic model is proposed. The experimentally observed sharp‐tip enhanced reaction and the maximal producing rate of carbon monoxide under different electrode potentials are well‐reproduced. Moreover, the optimal performance shows a strong dependence on the interaction between CO₂ and the local electric field, on the adsorption rate of CO₂, but not on the reaction barrier. Two new strategies to further enhance the reaction rate have also been proposed. The findings highlight the importance of kinetics in modeling electrocatalytic reactions.     

Transition metal promoted carboxylation of unsaturated substrates with carbon dioxide

The use of CO₂ as a C1 building block for the synthesis of useful chemicals is of great significance, and has attracted increasing attention in recent years. The transition metal catalyzed or mediated addition of CO₂ to unsaturated chemical bonds has proved to be a powerful and versatile protocol for the incorporation of CO₂ into various unsaturated organic substrates such as alkynes, alkenes, allenes, aldehydes, and 1,3-dienes. The hydrogenative, alkylative and arylative carboxylation, heterocarboxylation, and carboxylative cyclization with CO₂ have led to efficient and selective formation of various functionalized carboxylic acids and derivatives. This review focuses on recent advances in this area with emphasis on conceptual reaction design.     

Hexavalent symmetric graphs of order 9p

A graph is symmetric if its automorphism group acts transitively on the set of arcs of the graph. In this paper, we classify hexavalent symmetric graphs of order $9p$ for each prime $p$.     

Optimization Implementation and Characterization of the Equal Allocation of Nonseparable Costs Value

This paper devotes to the study of the equal allocation of nonseparable costs value for cooperative games. On the one hand, we show that the equal allocation of nonseparable costs value is the unique optimal solution that minimizes the total complaints for individual players over the pre-imputation set. On the other hand, analogously to the way of determining the Nucleolus, we obtain the equal allocation of nonseparable costs value by applying the lexicographic order over the individual complaints. Moreover, we offer alternative characterizations of the equal allocation of nonseparable costs value by proposing several new properties such as dual nullifying player property, dual dummifying player property and grand marginal contribution monotonicity.     

Bounds for pairs in judicious partitioning of graphs

In 2002, Bollobás and Scott posed the following problem: for an integer and a graph G of m edges, what is the smallest f (k, m ) such that V (G ) can be partitioned into V ₁,…,V _k in which for all , where denotes the number of edges with both ends in ? In this paper, we solve this problem asymptotically by showing that . We also show that V (G ) can be partitioned into such that for , where Δ denotes the maximum degree of G . This confirms a conjecture of Bollobás and Scott. © 2016 Wiley Periodicals, Inc. Random Struct. Alg., 50, 59–70, 2017     

A fractional spectral method with applications to some singular problems

In this paper we propose and analyze fractional spectral methods for a class of integro-differential equations and fractional differential equations. The proposed methods make new use of the classical fractional polynomials, also known as Müntz polynomials. We first develop a kind of fractional Jacobi polynomials as the approximating space, and derive basic approximation results for some weighted projection operators defined in suitable weighted Sobolev spaces. We then construct efficient fractional spectral methods for some integro-differential equations which can achieve spectral accuracy for solutions with limited regularity. The main novelty of the proposed methods is that the exponential convergence can be attained for any solution u(x) with u(x ^1/λ ) being smooth, where λ is a real number between 0 and 1 and it is supposed that the problem is defined in the interval (0,1). This covers a large number of problems, including integro-differential equations with weakly singular kernels, fractional differential equations, and so on. A detailed convergence analysis is carried out, and several error estimates are established. Finally a series of numerical examples are provided to verify the efficiency of the methods.     

The Protection of Lactic Acid Bacteria Fermented-Mango Peel against Neuronal Damage Induced by Amyloid-Beta

Mango peels are usually discarded as waste; however, they contain phytochemicals and could provide functional properties to food and promote human health. This study aimed to determine the optimal lactic acid bacteria for fermentation of mango peel and evaluate the effect of mango peel on neuronal protection in Neuron-2A cells against amyloid beta (Aβ) treatment (50 μM). Mango peel can be fermented by different lactic acid bacteria species. Lactobacillus acidophilus (BCRC14079)-fermented mango peel produced the highest concentration of lactic acid bacteria (exceeding 10⁸ CFU/mL). Mango peel and fermented mango peel extracts upregulated brain-derived neurotrophic factor (BDNF) expression for 1.74-fold in Neuron-2A cells. Furthermore, mango peel fermented products attenuated oxidative stress in Aβ-treated neural cells by 27%. Extracts of L. acidophilus (BCRC14079)-fermented mango peel treatment decreased Aβ accumulation and attenuated the increase of subG1 caused by Aβ induction in Neuron-2A cells. In conclusion, L. acidophilus (BCRC14079)-fermented mango peel acts as a novel neuronal protective product by inhibiting oxidative stress and increasing BDNF expression in neural cells.