Le Touquet – Paris-Plage, France
Le Touquet – Paris-Plage, France

Time filter

Source Type

When Dmitri Mendeleev (1834 - 1907) proposed his periodic law in 1869 on a pedagogical purpose, few teachers were enthusiastic. However, as early as 1873, a manual of chemistry already reproduced his periodic table. A renowned German chemist wrote it: Carl Friedrich Rammelsberg (1813 - 1899). With the exception of the chemists involved in the classification of the elements, he was, as far as we know, the first to present the periodic table of Mendeleev in a textbook.


van der Meijden A.,University of Antwerp | Herrel A.,Case postale | Summers A.,University of Washington
Journal of Zoology | Year: 2010

A key feature of the ancient body plan of scorpions is the pincer or chela. These multifunctional structures vary considerably in size and shape between different scorpion species. Here we provide the first comparative data on the pinching performance of the chelae of seven species of scorpions exemplifying the extremes of the shape range from slender to robust; Leiurus quinquestriatus, Androctonus amoreuxi, Androctonus australis, Hadogenes sp., Pandinus imperator, Scorpio maurus and Pandinus cavimanus (in the order of decreasing chela height to width ratio). Size-corrected chela height correlates highly with maximum pinch force. Independent contrasts suggest that the correlation of chela width, height and fixed finger length with maximum pinch force is independent of phylogeny, suggesting an adaptive component to the evolution of chela shape and performance. © 2009 The Authors. Journal compilation © 2009 The Zoological Society of London.


Ciezka M.,Wrocław University | Modelska M.,Wrocław University | Gorka M.,Wrocław University | Trojanowska-Olichwer A.,Wrocław University | Widory D.,Case postale
Journal of Atmospheric Chemistry | Year: 2015

The chemical compositions (Na+, NH4+, K+, Mg2+, Ca2+, Cl−, NO2−, NO3−, SO42−, HCO3−) of wet precipitation and nitrogen isotope compositions δ15N(NH4+) were studied from January to December 2010 in Wrocław (SW Poland). Results of a principle component analysis show that 82 % of the data variability can be explained by three main factors: 1) F1 (40 %) observed during vegetative season (electrical conductivity, HCO3−, NO3−, NO2−, NH4+ and SO42−), mainly controlling rainwater mineralization; 2) F2 (26 %) observed during vegetative and heating seasons (K+, Ca2+ and Mg2+), probably representing a combination of two processes: anthropogenic dusts and fertilizers application in agricultural fields, and 3) F3 (16 %) reported mainly during heating season (Na+ and Cl−) probably indicating the influence of marine aerosols. Variations of δ15N(NH4+) from −11.5 to 18.5 ‰ identify three main pathways for the formation of NH4+: 1) equilibrium fractionation between NH3 and NH4+; 2) kinetic exchange between NH3 and NH4+; 3) NH4+ exchange between atmospheric salts particles and precipitation. The coupled chemical/statistical analysis and δ15N(NH4+) approach shows that while fossil fuels burning is the main source of NH4+ in precipitation during the heating season, during the vegetative season NH4+ originates from local sewage irrigation fields in Osobowice or agricultural fertilizers. © 2015 The Author(s)

Loading Case postale collaborators
Loading Case postale collaborators