Non-contact elastography methods in mechanobiology: a point of view.

In recent decades, mechanobiology has emerged as a novel perspective in the context of basic biomedical research. It is now widely recognized that living cells respond not only to chemical stimuli (for example drugs), but they are also able to decipher mechanical cues, such as the rigidity of the underlying matrix or the presence of shear forces. Probing the viscoelastic properties of cells and their local microenvironment with sub-micrometer resolution is required to study this complex interplay and dig deeper into the mechanobiology of single cells. Current approaches to measure mechanical properties of adherent cells mainly rely on the exploitation of miniaturized indenters, to poke single cells while measuring the corresponding deformation. This method provides a neat implementation of the everyday approach to measure mechanical properties of a material, but it typically results in a very low throughput and invasive experimental protocol, poorly translatable towards three-dimensional living tissues and biological constructs. To overcome the main limitations of nanoindentation experiments, a radical paradigm change is foreseen, adopting next generation contact-less methods to measure mechanical properties of biological samples with sub-cell resolution. Here we briefly introduce the field of single cell mechanical characterization, and we concentrate on a promising high resolution optical elastography technique, Brillouin spectroscopy. This non-contact technique is rapidly emerging as a potential breakthrough innovation in biomechanics, but the application to single cells is still in its infancy.

Stereocontrol mechanism in CO/p-methylstyrene copolymerisation catalysed by aryl-alpha-diimine Pd(II) complexes.

Structural analysis of the first steps of isotactic CO/p-methylstyrene copolymerisation, catalysed by aryl-alpha-diimine Pd(II) complexes, highlights the influence of steric effects on the stereoselectivity of olefin insertion.

The right hemisphere contribution to semantic categorization: a TMS study.

A large amount of evidence suggests an involvement of the right hemisphere in lexical-semantic processing, but its specific contribution compared to the left hemisphere is not entirely clear. The present study investigated the contribution of both hemispheres to the semantic categorization process of words referring to typical and atypical exemplars. Transcranial Magnetic Stimulation (TMS) was used to interfere with the online activity of Wernicke's area and its right homologue during a verbal category membership task. The TMS delayed the responses to typical member nouns compared to the control condition, over both areas of interest. On the contrary, a delay in the responses to atypical member nouns was observed only when the right Wernicke's area was stimulated. Overall, these results indicate that while both hemispheres are involved in the categorization of typical exemplars, the right hemisphere specifically contributes to semantic categorization of atypical ones.