Brillouin scattering of phonons in complex materials

Initially, the theory of propagation of long-wavelength acoustic phonons and Brillouin scattering of laser light in condensed matter is concisely summarized. Then, the case of two relevant classes of complex materials in which Brillouin scattering can be measured is reviewed. First, in lowdensity, low-dimensional, disordered materials, the crossover between confinement and propagation is discussed on the basis of experimental findings. Moreover, the possibility of measuring the local mechanical properties of these materials at the mesoscale by Brillouin scattering is critically discussed. Second the application of Brillouin scattering to biological materials, a rather hot topic, is presented

Mechanical instabilities of metals Temperature changes during deforrnotion are indices of fundamental processes

ln the general context of the non-.linear thermodynamics of irreversible phenomena, the.thermoelasioptastic between transition occurring at the boundary the thermoelastic and thermoplastic régimes of deformation br m"ta,ttic À"terials can be seén as a bifurcation point. This non-equilibrium phase transformation is detected by measuing lhe rcmperature changes in a sample unaergoiij àefo,r;;i;;, since these are indices of fundamental processes" initial cooiingunderaÚiabaticconditionsdueíothethirÀiaelastice"fferítLorakitini,'185' )issuddentyfollowedbyarise il.r?!!?,::yn cau2_e-( bv entropy próduction in the highty irreversitte tnerÀiItastìc regime beyoìna tÀe niriícation. tnermal emtsston (l E) at and.beyond yielding can also be usefully exploited, tógether,ilith acoústic emiisiotn-if required, in the investigation of thermodynamic transformations or mechanlcal instabilities durin'g *nirn m,ecn'anìiat *ork is converted into thermal energy, as in creep, fatigue and fracture, for example

Multiscale Effect of Hierarchical Self-Assembled Nanostructures on Superhydrophobic Surface

In this work, we describe self-assembled surfaces with a peculiar multiscale organization, from the nanoscale to the microscale, exhibiting the Cassie–Baxter wetting regime with extremely low water adhesion: floating drops regime with roll-off angles < 5°. These surfaces comprise bundles of hierarchical, quasi-one-dimensional (1D) TiO2 nanostructures functionalized with a fluorinated molecule (PFNA). While the hierarchical nanostructures are the result of a gas-phase self-assembly process, their bundles are the result of the capillary forces acting between them when the PFNA solvent evaporates. Nanometric features are found to influence the hydrophobic behavior of the surface, which is enhanced by the micrometric structures up to the achievement of the superhydrophobic Cassie–Baxter state (contact angle (CA) ≫ 150°). Thanks to their high total and diffuse transmittance and their self-cleaning properties, these surfaces could be interesting for several applications such as smart windows and photovoltaics where light management and surface cleanliness play a crucial role. Moreover, the multiscale analysis performed in this work contributes to the understanding of the basic mechanisms behind extreme wetting behaviors

Multiscale Effect of Hierarchical Self-Assembled Nanostructures on Superhydrophobic Surface

In this work, we describe self-assembled surfaces with a peculiar multiscale organization, from the nanoscale to the microscale, exhibiting the Cassie–Baxter wetting regime with extremely low water adhesion: floating drops regime with roll-off angles < 5°. These surfaces comprise bundles of hierarchical, quasi-one-dimensional (1D) TiO₂ nanostructures functionalized with a fluorinated molecule (PFNA). While the hierarchical nanostructures are the result of a gas-phase self-assembly process, their bundles are the result of the capillary forces acting between them when the PFNA solvent evaporates. Nanometric features are found to influence the hydrophobic behavior of the surface, which is enhanced by the micrometric structures up to the achievement of the superhydrophobic Cassie–Baxter state (contact angle (CA) ≫ 150°). Thanks to their high total and diffuse transmittance and their self-cleaning properties, these surfaces could be interesting for several applications such as smart windows and photovoltaics where light management and surface cleanliness play a crucial role. Moreover, the multiscale analysis performed in this work contributes to the understanding of the basic mechanisms behind extreme wetting behaviors

TTC19 Plays a Husbandry Role on UQCRFS1 Turnover in the Biogenesis of Mitochondrial Respiratory Complex III.

Loss-of-function mutations in TTC19 (tetra-tricopeptide repeat domain 19) have been associated with severe neurological phenotypes and mitochondrial respiratory chain complex III deficiency. We previously demonstrated the mitochondrial localization of TTC19 and its link with complex III biogenesis. Here we provide detailed insight into the mechanistic role of TTC19, by investigating a Ttc19?/? mouse model that shows progressive neurological and metabolic decline, decreased complex III activity, and increased production of reactive oxygen species. By using both the Ttc19?/? mouse model and a range of human cell lines, we demonstrate that TTC19 binds to the fully assembled complex III dimer, i.e., after the incorporation of the iron-sulfur Rieske protein (UQCRFS1). The in situ maturation of UQCRFS1 produces N-terminal polypeptides, which remain bound to holocomplex III. We show that, in normal conditions, these UQCRFS1 fragments are rapidly removed, but when TTC19 is absent they accumulate within complex III, causing its structural and functional impairment.NRJ-Institut de France (M.Z), Association Francaise contre les Myopathies (AFM) grant 16086 (E.F.-V.)