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Abstract: Graphene oxide (GO) nanosheets impregnated with silver nanoparticles (Ag NPs) were fabricated by the in situ reduction of adsorbed Ag+ by hydroquinone (HQ) in a citrate buffer solution. Paper-like Ag NP/GO composite materials were fabricated owing to convenient structure characterization and antibacterial tests. The Ag NP/GO composites were characterized by UV–vis spectra, transmission electron microscope, electron diffraction, Raman spectroscopy, and field emission scanning electron microscope coupled with Energy Dispersive Spectrometer. Antibacterial activity was tested using Escherichia coli and Staphylococcus aureus as model strains of Gram negative and Gram positive bacteria, respectively. The as-prepared composites exhibit stronger antibacterial activity against both. The Ag NP/GO composites performed efficiently in bringing down the count of E. coli from 106 cfu/mL to zero with 45mg/L GO in water. The micron-scale GO nanosheets (lateral size) enable them to be easily deposited on porous ceramic membranes during water filtration; making them a promising biocidal material for water disinfection. [Copyright &y& Elsevier]

Abstract: In the first part of this paper, we introduce the notions of upper weight, lower weight and weight of subsequences of natural numbers and investigate some new estimations about Banach limits by using some results from Sucheston [L. Sucheston, On existence of finite invariant measures, Math. Z. 86 (1964) 327–336; L. Sucheston, Banach limit, Amer. Math. Monthly 74 (1967) 308–311]. In the second part of this paper, we study the connections between weights and densities of subsequences of natural numbers, and give a familiar formula to find some values of Banach limits on almost convergent sequences. [Copyright &y& Elsevier]

For a ∈ (0 , 1 / 2 ] and r ∈ (0 , 1) , let K a (r) and E a (r) (K (r) and E (r)) denote the generalized elliptic integrals (the complete elliptic integrals, respectively) of the first and second kinds, respectively. In this paper, the authors present the necessary and sufficient conditions under which certain familiar combinations defined in terms of the generalized elliptic integrals and elementary functions are monotone in a ∈ (0 , 1 / 2 ]. By these results, sharp bounds expressed in terms of K (r) , E (r) and elementary functions are obtained for K a (r) and E a (r) , thus showing the dependence on the parameter a of K a (r) and E a (r) , and substantially improving the known related results. [ABSTRACT FROM AUTHOR]