A new HPLC-MS/MS method for the simultaneous determination of quercetin and its derivatives in green coffee beans

Green coffee (Coffee arabica and Coffee robusta) is one of the most commonly traded goods globally. Their beans are enriched with polyphenols and numerous health benefits are associated with their consumption. The main aim of this work was to develop a new and fast analytical HPLC-MS/MS method to simultaneously determine six flavonoid polyphenolic compounds (quercetin, rutin, isorhamnetin, quercetin-3-glucouronide, hyperoside, and quercitrin) in 22 green coffee samples from six different geographical origins (Ethiopia, Brazil, Guatemala, Nicaragua, India and Colombia). In addition, by adjusting pH, temperature, solvent type, and extraction duration, several extraction methods such as acidic and alkaline hydrolysis, and extraction without hydrolysis were evaluated. The optimal extraction procedure in terms of recovery percentages (78.67–94.09%)was acidic hydrolysis at pH 2, extraction temperature of 60 °C, extraction solvent of 70% ethanol, and extraction duration of 1.5 h. Hyperoside (878–75 μg/kg) was the most abundant compound followed by quercitrin (408–38 μg/kg), quercetin (300–36 μg/kg), rutin (238–21 μg/kg), and quercetin-3-glucouronide (225–7 μg/kg), while isorhamnetin (34–3 μg/kg) showed the lowest amount. Overall, green coffee beans are rich in flavonoid polyphenolic compounds and could be used as part of a healthy diet

Universit\ue0 degli studi di Macerata

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El comportamiento post-critico de las vigas de acero armadas con chapas delgadas

An advance of expositions concerning the method of ultimate strength or post-critical strength of steel beams reinforced with thin plates is presented. This method is being object of experimental researches at the Applied Mechanics and Structures Institute (IMAE) of the Mathematics and Engineering Faculty, National University, Rosario (Argentina).Se presenta un avance de planteamientos relativos al método de la resistencia última o resistencia post-crítica de vigas de acero armadas con chapas delgadas, el cual está siendo objeto de investigaciones experimentales en el Instituto de Mecánica Aplicada y Estructuras (IMAE) de la Facultad de Ciencias Exactas e Ingeniería de la Universidad Nacional de Rosario (República Argentina)

Application of Hansch’s Model to Capsaicinoids and Capsinoids: A Study Using the Quantitative Structure−Activity Relationship. A Novel Method for the Synthesis of Capsinoids

We describe a synthetic approach for two families of compounds, the capsaicinoids and capsinoids, as part of a study of the quantitative relationship between structure and activity

Tuning chelation by the surfactant-like peptide A6H using predetermined pH values

We examine the self-assembly of a peptide A6H comprising a hexa-alanine sequence A6 with a histidine (H) “head group”, which chelates Zn2+ cations. We study the self assembly of A6H and binding of Zn2+ ions in ZnCl2 solutions, under acidic and neutral conditions. A6H self-assembles into nanotapes held together by a β-sheet structure in acidic aqueous solutions. By dissolving A6H in acidic ZnCl2 solutions, the carbonyl oxygen atoms in A6H chelate the Zn2+ ions and allow for β-sheet formation at lower concentrations, consequently reducing the onset concentration for nanotape formation. A6H mixed with water or ZnCl2 solutions under neutral conditions produces short sheets or pseudocrystalline tapes, respectively. The imidazole ring of A6H chelates Zn2+ ions in neutral solutions. The internal structure of nanosheets and pseudocrystalline sheets in neutral solutions is similar to the internal structure of A6H nanotapes in acidic solutions. Our results show that it is possible to induce dramatic changes in the self-assembly and chelation sites of A6H by changing the pH of the solution. However, it is likely that the amphiphilic nature of A6H determines the internal structure of the self-assembled aggregates independent from changes in chelation

Locally produced food for restaurants: a theoretical approach for the supply chain network design

Purpose This paper evaluates the feasibility and benefits of a local food distribution system, which connects farmers and restaurant owners from a logistics perspective. This paper considers a platform to improve operations and investigates various schemes for delivering locally produced food to restaurants using a food hub. Design/methodology/approach To compare distribution scenarios and derive managerial implications, a simulation model has been developed and executed in Matlab 2019a (c). The model evaluates various settings of business connections between farmers and restaurateurs. Findings Results of computational experiments highlight great potentials of such a system, particularly to reduce travel distances. To obtain these positive externalities, the local system requires specific attention during the design of logistical aspects and needs to be planned following a specific structure. Practical implications The developed simulation model can be used to improve understanding of related short food supply chains by analyzing specific cases where the main actors involved differ in terms of type, number, and location. Originality/value The paper analyzes the feasibility and the effects of a new distribution system that can connect supply chain actors directly. The analyses focus on logistics aspects, a topic that is often neglected in sustainable consumption research. Furthermore, the paper does not focus of a single case study but develops a customizable model to be used in various settings

Understanding the rich physics of light propagation in slow photonic crystal waveguides

Selected papers. Held as part of SPIE Photonics West 2010.We study propagation losses in slow light photonic crystal waveguides and show that dispersion engineering can reduce the loss. We develop an improved understanding of why and how this occurs and develop an new approach to modeling these devices that provides new design insights.Postprin