Search

The springtail Megalothorax laevis Denis, 1948 is redescribed from a broad sampling in the intertropical zone: Vietnam (including type locality), Ivory Coast, Gabon, Réunion island and French Guiana. Pseudopore-like elements are for the first time reported on the trunk and legs of Megalothorax species. New molecular data for M. laevis (16S rDNA, 28S rDNA d1 and d2 and COI Barcode) are provided. The phylogenetic position of the species within the Megalothorax genus is analysed. Megalothorax laevis belongs to the incertus group but shares similitudes with the minimus group acquired through evolutionary convergences (such as smooth lamellae of the mucro). Those similitudes might have created confusion between M. minimus and M. laevis. While M. minimus used to be regarded cosmopolitan, M. laevis has been overlooked since its original discovery. However, the present sampling led us to believe that M. laevis replace M. minimus as the commonest edaphic Megalothorax species in the intertropical zone. A key to the Megalothorax species with smooth mucro lamellae is provided. [ABSTRACT FROM AUTHOR]

This work reports measurements of the elastic modulus of halloysite nanotubes. Nanoscale three-point bending tests were performed on individual nanotubes using an atomic force microscope. Nanotubes exhibit elastic behaviour at small deformations. The stiffness of the tubes, and hence their elastic modulus, was deduced from force curve measurements using an appropriate mechanical model. The boundary conditions were also identified by recording the stiffness profile of a tube along its suspended length. An average elastic modulus of 140 GPa is obtained for a set of tubes with outer diameters ranging between 50 and 160 nm. Moreover, the elastic modulus increases with decreasing outer diameter, with a steep jump below 50 nm. The size dependence of the elastic modulus may be attributed to: (i) surface tension effects for thinner tubes and (ii) a non-negligible contribution of shear deformations to the total deflection for larger tubes. [ABSTRACT FROM AUTHOR]

Plasma activation effects on automotive polymers by low temperature plasma at atmospheric pressure have been studied. The aim of this work was the improvement of the polymer surface polarity in order to replace the use of adhesive layers before application of lacquering. Two different concepts of dielectric barrier discharge, direct and indirect plasma treatment, were applied. The efficiency of such plasma treatment was determined by adhesive pull strength tests and surface energy calculations. It was shown that both plasma treatment methods allow a significant increase in surface polarity up to a factor of 20 and adhesive pull strength of lacquers up to a factor of 29 respectively. In comparison to indirect surface treatment, the direct treatment features a higher efficiency in terms of increasing both, polarity and adhesive pull strength. [ABSTRACT FROM AUTHOR]

Abstract The phylogenetic study of the origin of a ‘true’ worker caste in termites by Thompson et al . [ J. Evol. Biol. 13 (2000) 869] did not take into account all possibilities of character coding and character optimization on the phylogenetic tree. Actually, contrary to the authors' statements, the phylogenetic evidence presented does not permit to answer decisively most of the questions asked concerning the origin and evolution of worker castes in termites. Particular attention was paid to assumptions implied by the coding of the characters of interest, namely concerning the homology between pseudergates and a ‘true’ worker caste and the kind of the cockroach life type. [ABSTRACT FROM AUTHOR]

Copyright of Langenbecks Archiv fuer Chirurgie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The evolution of the ‘true’ worker caste in termites is not decisively inferred by coding and mapping both this character and the foraging behaviour on a phylogenetic tree. Answering to Thompson et al. (2000, 2003), and with reference to Grandcolas and D'Haese (2002), we show that this indecisive inference depends on the correct consideration paid to the outgroups. These last ones could be non subsocial cockroaches, or some wood-eating subsocial cockroaches often considered misleadingly as living ancestors, or even any hemimetabolous insects, all of them would be unambiguously lacking ‘true’ worker caste and pseudergate caste and not showing the ‘one-piece’ life type foraging behaviour. These statements derive from observing, coding and mapping the real world on the tree without making ad hoc assumptions. In that respect, because termites do not exist in isolation, apart from the tree of life, mapping the character of interest on the tree must be applied to the outgroups as well. [ABSTRACT FROM AUTHOR]