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Some amphibians, such as tree frogs, torrent frogs, newts, are able to climb or attach to wet slippery smooth surfaces, even in a vertical or overhanging state, by their reliable reversible adhesions developed on the epidermal of toe pads. It is widely believed that such outstanding function originates from the possible factors of the specialized evolutions of surficial micro/nanostructures, the chemical components of secreted mucus, the solid-liquid behavior of epidermal and the bulk softness of toe pads. In this review, we summarize the main physical mechanisms of these factors behaving underlying the wet adhesion of toe pads from the researches on biological models to artificial counterparts. The discussion of the organism attachments, the interfacial physical forces and the switchable strategies for artificial wet adhesion are also included. The paper gives a deeply, comprehensively understanding of the characters of wet adhesives on amphibians, which performs necessarily for the new strategies of exploring artificial adhesive surfaces., (Copyright © 2020 Elsevier B.V. All rights reserved.)

With the closure of the border with then-Macedonia in early 2016, it was foreseeable that Greece would become the "last station" for a large number of refugees. Flanked by the agreement between Turkey and the European Union of March 2016, Greece underwent a profound transformation from a transit country to a recipient country. Through a new regulation, the Emergency Support Instrument, initially activated by the European Commission 2016-2019, international humanitarian aid operations were supported for the first time in the EU. The article analyzes the resulting frictions on the basis of empirical field research and a broad literature review. While frictions similar to those in other non-European humanitarian operations exist, specific peculiarities due to the operation taking place in an austerity-ridden member state of the EU must also be noted., Competing Interests: Competing interestsThe authors declare that they have no competing interests., (© The Author(s) 2021.)