Homogenization of the vibro-acoustic transmission on periodically perforated elastic plates interacting with flow

We consider acoustic waves propagating in an inviscid fluid interacting with a rigid periodically perforated plate in the presence of permanent flows. The paper presents a model of an acoustic interface obtained by the asymptotic homogenization of a thin transmission layer in which the plate is embedded. To account for the flow, a decomposition of the fluid pressure and velocity in the steady and fluctuating parts is employed. This enables for a linearization and an efficient use of the homogenization method which leads to a model order reduction effect. The dependence of an extended Helmholtz equation on the permanent flow introduces a locally periodic velocity field in the perforated plate vicinity, so that the coefficients of the homogenized interface depend on the flow. The derived model extended by natural coupling conditions provides an implicit Dirichlet-to-Neumann operator. Numerical simulations of wave propagation in a waveguide illustrate the flow speed influence on the acoustic transmission. Also some geometrical aspects are explored

Multiscale modelling of flow due to the peristaltic wave in deforming poro-piezoelectric medium

The paper reports on the homogenization based modelling of fluid saturated poroelastic materials containing locally controlable piezoelectric (PZ) actuators. This option provides metamaterial properties which enable to convert the electric power into the fluid transport due to the peristaltic deformation wave induced by the propagating voltage wave. A quasi-linear PZ-poroelastic material model is proposed to respect dependence of the effective medium parameters on the deformation at the microstructure (pore) level. Due to the sensitivity analysis of the homogenized coefficient, the two-scale modelling avoids any need to update the local microconfigurations. Numerical studies has been performed as the proof of the concept

Ultrafast Photo-Induced Charge Transfer Unveiled by Two-Dimensional Electronic Spectroscopy

The interaction of exciton and charge transfer (CT) states plays a central role in photo-induced CT processes in chemistry, biology and physics. In this work, we use a combination of two-dimensional electronic spectroscopy (2D-ES), pump-probe measurements and quantum chemistry to investigate the ultrafast CT dynamics in a lutetium bisphthalocyanine dimer in different oxidation states. It is found that in the anionic form, the combination of strong CT-exciton interaction and electronic asymmetry induced by a counter-ion enables CT between the two macrocycles of the complex on a 30 fs timescale. Following optical excitation, a chain of electron and hole transfer steps gives rise to characteristic cross-peak dynamics in the electronic 2D spectra, and we monitor how the excited state charge density ultimately localizes on the macrocycle closest to the counter-ion within 100 fs. A comparison with the dynamics in the radical species further elucidates how CT states modulate the electronic structure and tune fs-reaction dynamics. Our experiments demonstrate the unique capability of 2D-ES in combination with other methods to decipher ultrafast CT dynamics.Comment: 14 pages, 11 figures, and Supporting informatio

Publisher Correction: Genetic tool development in marine protists: emerging model organisms for experimental cell biology.

An amendment to this paper has been published and can be accessed via a link at the top of the paper

Genetic tool development in marine protists: emerging model organisms for experimental cell biology

Abstract: Diverse microbial ecosystems underpin life in the sea. Among these microbes are many unicellular eukaryotes that span the diversity of the eukaryotic tree of life. However, genetic tractability has been limited to a few species, which do not represent eukaryotic diversity or environmentally relevant taxa. Here, we report on the development of genetic tools in a range of protists primarily from marine environments. We present evidence for foreign DNA delivery and expression in 13 species never before transformed and for advancement of tools for eight other species, as well as potential reasons for why transformation of yet another 17 species tested was not achieved. Our resource in genetic manipulation will provide insights into the ancestral eukaryotic lifeforms, general eukaryote cell biology, protein diversification and the evolution of cellular pathways