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We present a systematic study of the intrinsic photostability of ITIC derivative acceptors, namely ITIC, ITIC-Th and ITIC-4F, in solution, in layers and in blends with donor polymers such as PBDB-T (also known as PCE12) or its fluorinated derivative PBDB-T-2F (known as PM6). We followed the evolution of the absorption spectra of ITIC derivative acceptors and blends under constant irradiation using different light sources (AM1.5 solar simulator, SUNTest or LED). Any interaction with oxygen under illumination was avoided by placing the solutions and thin films under inert conditions, i.e. nitrogen or vacuum. While donor polymers are highly photostable, all three NFAs show a common photodegradation process with the formation of photoproducts and molecular structure modifications under light exposure. Compared to the solutions where the degradation kinetics are very fast, the degradation in films is significantly slowed down. The corresponding photodegradation process including a cis–trans isomerisation of end groups is found to be common for all ITIC derivatives and independent of the light source. In blends, photodegradation is directly attributable to the acceptor, but varies according to the derivative. In fact, ITIC-4F based blends will benefit from a stabilizing mechanism due to a favorable molecular packing inside the blend. Thereafter, we have studied the photostability of blend layers post-annealed at different temperatures, and we show that the thermally induced packing and crystallinity of the ITIC derivatives dominate the photostability of the blends. We finally investigate the photostability of organic solar cells based on thermally annealed PM6:ITIC-4F blend layers. [ABSTRACT FROM AUTHOR]

We theoretically and experimentally study the structuration of organic solar cells in the shape of photonic crystal slabs. By taking advantage of the optical properties of photonic crystals slabs, we show the possibility to couple Bloch modes with very low group velocities in the active layer of the cells. These Bloch modes, also called slow Bloch modes (SBMs), allow increasing the lifetime of photons within the active layer. Finally, we present experimental demonstration performed by using nanoimprint to directly pattern the standard poly-3-hexylthiophène:[6,6]-phenyl-C61-butiryc acid methyl ester organic semiconductor blend in thin film form in the shape of a photonic crystal able to couple SBMs. In agreement with the model, optical characterizations will demonstrate significant photonic absorption gains. [ABSTRACT FROM AUTHOR]

Protein function is generally dependent on its subcellular localization. In gram-negative bacteria such as Escherichia coli, a protein can be targeted to five different compartments: the cytoplasm, the inner membrane, the periplasm, the outer membrane, and the extracellular medium. Different approaches can be used to determine the protein localization within cell such as in silico identification of protein signal sequences and motifs, electron microscopy and immunogold labeling, optical fluorescence microscopy, and biochemical technics. In this chapter, we describe a simple and efficient method to isolate the different compartments of Escherichia coli by a fractionation method and to determine the presence of the protein of interest. For inner membrane proteins, we propose a method to discriminate between integral and peripheral membrane proteins., (© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Filamentous phages are one of the simplest examples of viruses with a protein capsid that protects a circular single-stranded DNA genome. The infection is very specific, nonlytic, and can strongly affect the physiology or provide new pathogenic factors to its bacterial host. The infection process is proposed to rely on a pore-forming mechanism similar to that of certain nonenveloped eukaryotic viruses. The Ff coliphages (including M13, fd, and f1) have been intensively studied and were used to establish the sequence of events taking place for efficient crossing of the host envelope structure. However, the mechanism involved in the penetration of the cell inner membrane is not well understood. Here, we identify new host players involved in the phage translocation mechanism. Interaction studies by a combination of in vivo biochemical methods demonstrate that the adhesion protein pIII located at the tip of the phage binds to TolQ and TolR, two proteins that form a conserved proton-dependent molecular motor in the inner membrane of the host cell. Moreover, in vivo cysteine cross-linking studies reveal that the interactions between the pIII and TolQ or TolR occur between their transmembrane helix domains and may be responding to the proton motive force status of the cell. These results allow us to propose a model for the late stage of filamentous phage translocation mediated by multiple interactions with each individual component of the host TolQRA complex., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

True north can be determined on Earth by three means: magnetic compasses, stars, and via the global navigation satellite systems (GNSS), each of which has its own drawbacks. GNSS are sensitive to jamming and spoofing, magnetic compasses are vulnerable to magnetic interferences, and the stars can be used only at night with a clear sky. As an alternative to these methods, nature-inspired navigational cues are of particular interest. Celestial polarization, which is used by insects such as Cataglyphis ants, can provide useful directional cues. Migrating birds calibrate their magnetic compasses by observing the celestial rotation at night. By combining these cues, we have developed a bioinspired optical method for finding the celestial pole during the daytime. This method, which we have named SkyPole, is based on the rotation of the skylight polarization pattern. A polarimetric camera was used to measure the degree of skylight polarization rotating with the Sun. Image difference processes were then applied to the time-varying measurements in order to determine the north celestial pole's position and thus the observer's latitude and bearing with respect to the true north.

Chromate is a toxic metal that enters bacteria by using oxyanion importers. Here, we show that each mutant of the Tol-Pal system of Escherichia coli exhibited increased chromate resistance. This system, which spans the cell envelope, plays a major role in envelope integrity and septation. The ΔtolQR mutant accumulated three-fold less chromate than the wild-type. Addition of phosphate but not sulfate to rich medium drastically reduced chromate toxicity and import in the wild-type strain. Furthermore, the intracellular concentration of free inorganic phosphate was significantly reduced for the ΔtolR mutant in comparison to the wild-type strain. Moreover, extracellular labeled phosphate was significantly less incorporated into the ΔtolR mutant. Finally, two distinct TolQR mutant complexes, specifically affected in Tol-Pal energization without affecting the TolQRA complex structure, did not complement the ΔtolQR mutant for inorganic phosphate accumulation. We thus propose that, while the Pst system is well known to import inorganic phosphate, the Tol-Pal system participates to phosphate uptake in particular at medium to high extracellular phosphate concentrations. Since mutations disabling the Tol-Pal system lead to pleiotropic effects, chromate resistance and reduced inorganic phosphate import could occur from an indirect effect of mutations in components of the Tol-Pal system., Competing Interests: Declaration of competing interest The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results., (Copyright © 2022 CNRS and Aix-Marseille Université. Published by Elsevier Masson SAS.. All rights reserved.)

This work describes the self-assembled monolayers (SAMs) of two ferrocene derivatives with two anchoring groups (at the bottom and at the top of the SAM) deposited on ultraflat template-stripped gold substrates by cyclic voltammetry and analyzed by complementary surface characterization techniques. The SAM of each molecule is deposited by three different protocols: direct deposition (one step), click reaction on the surface (two steps), and reverse click reaction on the surface (two steps). The SAM structure is well studied to determine the SAM orientation, SAM arrangement, and ferrocene position within the SAM. Electron transfer kinetics have also been studied, which agree with the quality of each SAM. With the help of two anchoring groups and click-chemistry active functional groups, we have shown that the two molecules can be deposited by controlling the position of ferrocene at either end. We further investigated the involvement of the triazole five-membered ring in the electron transfer mechanism. We have found that a carbon spacer between ferrocene and triazole improves the SAM packing. This study enhances the understanding of tethering thiol and thiol acetate anchoring groups on gold by a controlled orientation, which may help in the development of functional molecular devices requiring two anchoring groups.

Objective. In this study, we assessed the impact of electroencephalography-functional magnetic resonance imaging (EEG-fMRI) neurofeedback (NF) on connectivity strength and direction in bilateral motor cortices in chronic stroke patients. Most of the studies using NF or brain computer interfaces for stroke rehabilitation have assessed treatment effects focusing on successful activation of targeted cortical regions. However, given the crucial role of brain network reorganization for stroke recovery, our broader aim was to assess connectivity changes after an NF training protocol targeting localized motor areas. Approach. We considered changes in fMRI connectivity after a multisession EEG-fMRI NF training targeting ipsilesional motor areas in nine stroke patients. We applied the dynamic causal modeling and parametric empirical Bayes frameworks for the estimation of effective connectivity changes. We considered a motor network including both ipsilesional and contralesional premotor, supplementary and primary motor areas. Main results. Our results indicate that NF upregulation of targeted areas (ipsilesional supplementary and primary motor areas) not only modulated activation patterns, but also had a more widespread impact on fMRI bilateral motor networks. In particular, inter-hemispheric connectivity between premotor and primary motor regions decreased, and ipsilesional self-inhibitory connections were reduced in strength, indicating an increase in activation during the NF motor task. Significance. To the best of our knowledge, this is the first work that investigates fMRI connectivity changes elicited by training of localized motor targets in stroke. Our results open new perspectives in the understanding of large-scale effects of NF training and the design of more effective NF strategies, based on the pathophysiology underlying stroke-induced deficits., (© 2021 IOP Publishing Ltd.)

Multicopper oxidases (MCOs) catalyze the oxidation of a variety of substrates while reducing oxygen into water through four copper atoms. As an additional feature, some MCOs display an enhanced activity in solution in the presence of Cu 2+ . This is the case of the hyperthermophilic laccase HB27 from Thermus thermophilus , the physiologic role of which is unknown. As a particular feature, this enzyme presents a methionine rich domain proposed to be involved in copper interaction. In this work, laccase from T. thermophilus was produced in E. coli , and the effect of Cu 2+ on its electroactivity at carbon nanotube modified electrodes was investigated. Direct O 2 electroreduction is strongly dictated by carbon nanotube surface chemistry in accordance with the enzyme dipole moment. In the presence of Cu 2+ , an additional low potential cathodic wave occurs, which was never described earlier. Analysis of this wave as a function of Cu 2+ availability allows us to attribute this wave to a cuprous oxidase activity displayed by the laccase and induced by copper binding close to the Cu T1 center. A mutant lacking the methionine-rich hairpin domain characteristic of this laccase conserves its copper activity suggesting a different site of copper binding. This study provides new insight into the copper effect in methionine rich MCOs and highlights the utility of the electrochemical method to investigate cuprous oxidase activity and to understand the physiological role of these MCOs.