Dataset Information

The composition and friction-reducing properties of leaf layers.

ABSTRACT: Every autumn rail networks across the world suffer delays, accidents and schedule changes due to low friction problems caused by leaves landing on the rails. These leaves form a layer that can reduce the friction between the wheel and the rail to a similar level as that between ice and an ice-skate ( μ=0.01-0.05 ). Previous works have generated several hypotheses for the chemical reactions and low friction mechanism associated with these layers. In this work, the reaction between an aqueous extract of sycamore leaves and metallic iron is investigated. This reaction has been shown to produce a black precipitate, which matches field observations of leaf layers, while friction tests with these extracts produce characteristic ultra low friction. The reaction is investigated through FTIR, XPS, CHNS and ICP-MS analysis as well as wet chemical testing. The impact of the reaction on friction is investigated through three rounds of tribological testing. The results indicate that the black precipitate produced is iron tannate, formed by complexation of tannins with dissolved iron ions. Friction testing showed that eliminating tannins from the leaf extract resulted in a significant increase in the friction coefficient compared with the control.

SUBMITTER: Watson M

PROVIDER: S-EPMC7426055 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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The composition and friction-reducing properties of leaf layers.

Watson Michael M White Benjamin B Lanigan Joseph J Slatter Tom T Lewis Roger R

Proceedings. Mathematical, physical, and engineering sciences 20200729 2239

Every autumn rail networks across the world suffer delays, accidents and schedule changes due to low friction problems caused by leaves landing on the rails. These leaves form a layer that can reduce the friction between the wheel and the rail to a similar level as that between ice and an ice-skate ( μ = 0.01 - 0.05 ). Previous works have generated several hypotheses for the chemical reactions and low friction mechanism associated with these layers. In this work, the reaction between an aqueous ...[more]

PMID: 32831605

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Project description:The current work attempts to explore the influence of three extraction solvents on phytochemical composition, content of polyphenols, antioxidant potential, and antibacterial capacity of hydroethanolic, acetonic, and aqueous extracts from Moroccan Mentha longifolia leaves. To achieve this goal, the chemical composition was identified using an HPLC-DAD examination. The contents of polyphenols were assessed, while the total antioxidant capacity (TAC), the DPPH test, and the reducing power test (RP) were utilized to determine antioxidant capacity. To assess the antibacterial activity, the microdilution technique was carried out to calculate the minimum inhibitory (MIC) and minimum bactericidal concentrations (MBC) of extracts against four nosocomial bacteria (Bacillus cereus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus). Additionally, the antibacterial and antioxidant activities of all tested extracts were examined in silico against the proteins NADPH oxidase and Bacillus cereus phospholipase C. Study reveals that M. longifolia extracts contain high phenolic and flavonoids. Additionally, the hydroethanolic extract contained the highest amounts of phenolic and flavonoid content, with values of 23.52 ± 0.14 mg Gallic acid equivalent/g dry weight and 17.62 ± 0.36 mg Quercetin Equivalent/g dry weight, respectively compared to the other two extracts. The same extract showed the best antioxidant capacity (IC50 = 39 µg/mL ± 0.00), and the higher RP (EC50 of 0.261 ± 0.00 mg/mL), compared to the acetonic and aqueous extract regarding these tests. Furthermore, the hydroethanolic and acetonic extracts expressed the highest TAC (74.40 ± 1.34, and 52.40 ± 0.20 mg EAA/g DW respectively), compared with the aqueous extract. Regarding antibacterial activity, the MIC value ranges between 1.17 and 12.50 mg/mL. The in-silico results showed that the antibacterial activity of all extracts is principally attributed to kaempferol and ferulic acid, while antioxidant capacity is attributed to ferulic acid.

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The composition and friction-reducing properties of leaf layers.

Publications

The composition and friction-reducing properties of leaf layers.

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