Suchergebnisse

The Cape fur seal was an abundant resource in southern Africa, when first discovered by itinerant sailing vessels in the late 16th century. Seals were slaughtered indiscriminately by the sailors for skins, meat and oil for three centuries from around 1600 to 1899. Government controls over the sealing industry were first introduced as late as 1893, by which time at least 23 seal colonies had become extinct and the seal population had been significantly reduced. This paper reconstructs the historical seal harvest from the time of arrival of the first settlers in 1652 up to 1899. These data are then compared with modern harvest data from 1900 to 2000, illustrating the marked increase in the harvest from about 1950, and the concomitant recovery of the seal population to a level of around 1.5-2 million animals.

A cost-effective and scalable approach was developed to produce monodisperse Ni2−xCoxP nanocrystals (NCs) with composition tuned over the entire range (0 ≤ x ≤ 2). Ni2−xCoxP NCs were synthesized using low-cost, stable and low-toxicity triphenyl phosphite (TPP) as a phosphorus source, metal chlorides as metal precursors and hexadecylamine (HDA) as a ligand. The synthesis involved the nucleation of amorphous Ni–P and its posterior crystallization and simultaneous incorporation of Co. The composition, size and morphology of the Ni2−xCoxP NCs could be controlled simply by varying the ratio of Ni and Co precursors and the amounts of TPP and HDA. Ternary Ni2−xCoxP-based electrocatalysts exhibited enhanced electrocatalytic activity toward the hydrogen evolution reaction (HER) compared to binary phosphides. In particular, NiCoP electrocatalysts displayed the lowest overpotential of 97 mV at J = 10 mA cm−2 and an excellent long-term stability. DFT calculations of the Gibbs free energy for hydrogen adsorption at the surface of Ni2−xCoxP NCs showed NiCoP to have the most appropriate composition to optimize this parameter within the whole Ni2−xCoxP series. However, the hydrogen adsorption energy was demonstrated not to be the only parameter controlling the HER activity in Ni2−xCoxP. ; J. David and J. Arbiol acknowledge funding from Generalitat de Catalunya 2017 SGR 327 and the Spanish MINECO project VALPEC (ENE2017-85087-C3). ICN2 acknowledges support from the Severo Ochoa Programme (SEV-2013-0295) and is funded by the CERCA Programme/Generalitat de Catalunya. J. David has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 665919. J. Llorca is a Serra Hunter Fellow and is grateful to the ICREA Academia program and grants MINECO/FEDER ENE2015-63969-R and GC 2017 SGR 128. J. Liu, J. Li and X. Yu thank the China Scholarship Council for scholarship support. M. Meyns acknowledges a Juan de la Cierva formación grant by the Spanish MINECO. ; Peer reviewed