Horizontally-aligned carbon nanotubes arrays and their interactions with liquid crystal molecules: Physical characteristics and display applications

We report on the physical characteristics of horizonthally-grown Single-Walled Carbon Nanotubes (h-al-SWNT) arrays and their potential use as transparent and conducting alignment layer for liquid crystals display devices. Microscopy (SEM and AFM), spectroscopic (Raman) and electrical investigations demonstrate the strong anisotropy of h-al-SWNT arrays. Optical measurements show that h-al-SWNTs are efficient alignment layers for Liquid Crystal (LC) molecules allowing the fabrication of optical wave plates. Interactions between h-al-SWNT arrays and LC molecules are also investigated evidencing the weak azimuthal anchoring energy at the interface, which, in turn, leads to LC devices with a high pretilt angle. The electro-optical reponses of h-al-SWNT/LC cells demonstrate that h-al-SWNT arrays are efficient nanostructured electrodes with potential use for the combined replacement of Indium Tin Oxyde and polymeric alignment layers in conventional displays

Activation of mutated TRPA1 ion channel by resveratrol in human prostate cancer associated fibroblasts (CAF)

Previous studies showed the effects of resveratrol (RES) on several cancer cells, including prostate cancer (PCa) cell apoptosis without taking into consideration the impact of the tumor microenvironment (TME). The TME is composed of cancer cells, endothelial cells, blood cells and cancer-associated fibroblasts (CAF), the main source of growth factors. The latter cells might modify in the TME the impact of RES on tumor cells via secreted factors. Recent data clearly show the impact of CAF on cancer cells apoptosis resistance via secreted factors. However, the effects of RES on PCa CAF have not been studied so far. We have investigated here for the first time the effects of RES on the physiology of PCa CAF in the context of TME. Using a prostate cancer CAF cell line and primary cultures of CAF from prostate cancers, we show that RES activates the N-terminal mutated Transient Receptor Potential Ankyrin 1 (TRPA1) channel leading to an increase in intracellular calcium concentration and the expression and secretion of growth factors (HGF and VEGF) without inducing apoptosis in these cells. Interestingly, in the present work, we also show that when the prostate cancer cells were co-cultured with CAF, the RES-induced cancer cell apoptosis was reduced by 40%, an apoptosis reduction canceled in the presence of the TRPA1 channel inhibitors. The present work highlights CAF TRPA1 ion channels as a target for RES and the importance of the channel in the epithelial-stromal crosstalk in the TME leading to resistance to the RES-induced apoptosis

Nightside condensation of iron in an ultra-hot giant exoplanet

Ultra-hot giant exoplanets receive thousands of times Earth's insolation. Their high-temperature atmospheres (>2,000 K) are ideal laboratories for studying extreme planetary climates and chemistry. Daysides are predicted to be cloud-free, dominated by atomic species and substantially hotter than nightsides. Atoms are expected to recombine into molecules over the nightside, resulting in different day-night chemistry. While metallic elements and a large temperature contrast have been observed, no chemical gradient has been measured across the surface of such an exoplanet. Different atmospheric chemistry between the day-to-night ("evening") and night-to-day ("morning") terminators could, however, be revealed as an asymmetric absorption signature during transit. Here, we report the detection of an asymmetric atmospheric signature in the ultra-hot exoplanet WASP-76b. We spectrally and temporally resolve this signature thanks to the combination of high-dispersion spectroscopy with a large photon-collecting area. The absorption signal, attributed to neutral iron, is blueshifted by -11+/-0.7 km s-1 on the trailing limb, which can be explained by a combination of planetary rotation and wind blowing from the hot dayside. In contrast, no signal arises from the nightside close to the morning terminator, showing that atomic iron is not absorbing starlight there. Iron must thus condense during its journey across the nightside.Comment: Published in Nature (Accepted on 24 January 2020.) 33 pages, 11 figures, 3 table

Physical and dynamical properties of photosensitive mesogenic electrolytes

Les électrolytes solides sont du plus grand intérêt scientifique tant du point de vue fondamental que pour les nombreuses applications technologiques potentielles, notamment les batteries rechargeables, les cellules énergétiques ou les capteurs. Les matériaux considérés aujourd’hui comme les plus prometteurs sont obtenus par dissolution d’un sel alcalin dans un milieu contenant des fonction poly(éthylène oxide) (PEO). Récemment, il a été montré que certains facteurs géométriques de ces (macro)molécules, comme la proximité d’éléments polaires ou non-polaires, le contrôle de la longueur de la chaine PEO ou l’organisation partielle des segments PEO, pouvaient aider à augmenter la conductivité ionique. Suivant ces hypothèses, ce travail consiste à étudier l’influence de l’organisation moléculaire au sein d’un électrolyte sur le transport des espèces chargées, notamment les ions lithium. Des composés présentant une phase cristal-liquide nématique et possédant des chaines PEO ont été dopés avec des sels de lithium. Par ailleurs, la présence d’une fonction azobenzène sur le cœur rigide de la molécule permet de contrôler la géométrie des molécules par photo-isomérisation sous irradiation UV. L’ordre de la phase nématique constituée de molécules de type bâtonnets peut donc être modifié par l’introduction de molécules en forme de chevrons. La conductivité ionique de ces composés a ensuite été évaluée par spectroscopie diélectrique dans les configurations planaire et homéotrope. Il a été mis en évidence que l’anisotropie influence le déplacement des charges et que les porteurs de charges se déplacent de façon favorisée en configuration planaire. L’influence de l’irradiation UV, et donc l’impact de l’ordre moléculaire a ensuite été exploré. Les irradiations entrainent une baisse de la conductivité ce qui met à nouveau l’importance de l’anisotropie sur la conductivité. Une étude courant/tension a été également menée afin d’étudier la dynamique de ces systèmes soumis à l’illumination. Enfin un gel électrolyte anisotrope a été élaboré. Les premiers résultats obtenus sur les propriétés électriques de ce gel semblent prometteur montrant une conductivité améliorée.Solid organic electrolytes are of major scientific interest from fundamental standpoint and they have numerous potential technological applications, such as high-capacity rechargeable batteries, fuel cells or sensors. One way to obtain these materials is to dissolve alkali salts into media based on poly(ethylene oxide) (PEO) derivatives. Recently, it has been demonstrated that some geometric factors of these (macro)molecules, such as proximity of polar and non-polar elements, PEO chain length or partial ordering of the PEO segments, can improve the ionic conductivity. Based on these observations, photosensitive mesogenic compounds bearing PEO chains were doped with lithium salts. The physical characteristics of these hybrid materials have been investigated by optical microscopy, X-Ray diffraction and broadband dielectric spectroscopy. In particular, the ionic conductivity has been studied for two different anchoring conditions, i.e., planar and homeotropic. It is shown that the anisotropy of the liquid crystalline phase influences the ionic conductivity of the sample and thus the charge motion. Planar anchoring conditions provided the highest ionic conductivity. Then, the impact of UV irradiation on the molecular order has been investigated. Upon UV light, a Trans-Cis isomerisation mechanism of the azobenzene moieties present in the chore of the molecules takes places inducing the transformation of stick-like shape molecules (nematic phase) to chevron-like shape molecules (isotropic state). This phenomenon strongly affects the ionic conductivity evidencing the major role of the anisotropy on the conduction process. In order to investigate the dynamic properties of these systems under illumination a current/voltage study has also been carried out showing the potential use of these photosensitive mesogenic electrolytes as sensors. Finally, the LC phase has been stabilized by using a polymerization mechanism of photosensitive mesogenic monomers. It is interesting to point out that the fabricated gel exhibits enhanced electrical properties compared to that of the non-stabilized LC phase

Etude des propriétés physiques et dynamiques d'électrolytes mésogènes photosensibles

Les électrolytes solides sont du plus grand intérêt scientifique tant du point de vue fondamental que pour les nombreuses applications technologiques potentielles, notamment les batteries rechargeables, les cellules énergétiques ou les capteurs. Les matériaux considérés aujourd hui comme les plus prometteurs sont obtenus par dissolution d un sel alcalin dans un milieu contenant des fonction poly(éthylène oxide) (PEO). Récemment, il a été montré que certains facteurs géométriques de ces (macro)molécules, comme la proximité d éléments polaires ou non-polaires, le contrôle de la longueur de la chaine PEO ou l organisation partielle des segments PEO, pouvaient aider à augmenter la conductivité ionique. Suivant ces hypothèses, ce travail consiste à étudier l influence de l organisation moléculaire au sein d un électrolyte sur le transport des espèces chargées, notamment les ions lithium. Des composés présentant une phase cristal-liquide nématique et possédant des chaines PEO ont été dopés avec des sels de lithium. Par ailleurs, la présence d une fonction azobenzène sur le cœur rigide de la molécule permet de contrôler la géométrie des molécules par photo-isomérisation sous irradiation UV. L ordre de la phase nématique constituée de molécules de type bâtonnets peut donc être modifié par l introduction de molécules en forme de chevrons. La conductivité ionique de ces composés a ensuite été évaluée par spectroscopie diélectrique dans les configurations planaire et homéotrope. Il a été mis en évidence que l anisotropie influence le déplacement des charges et que les porteurs de charges se déplacent de façon favorisée en configuration planaire. L influence de l irradiation UV, et donc l impact de l ordre moléculaire a ensuite été exploré. Les irradiations entrainent une baisse de la conductivité ce qui met à nouveau l importance de l anisotropie sur la conductivité. Une étude courant/tension a été également menée afin d étudier la dynamique de ces systèmes soumis à l illumination. Enfin un gel électrolyte anisotrope a été élaboré. Les premiers résultats obtenus sur les propriétés électriques de ce gel semblent prometteur montrant une conductivité améliorée.Solid organic electrolytes are of major scientific interest from fundamental standpoint and they have numerous potential technological applications, such as high-capacity rechargeable batteries, fuel cells or sensors. One way to obtain these materials is to dissolve alkali salts into media based on poly(ethylene oxide) (PEO) derivatives. Recently, it has been demonstrated that some geometric factors of these (macro)molecules, such as proximity of polar and non-polar elements, PEO chain length or partial ordering of the PEO segments, can improve the ionic conductivity. Based on these observations, photosensitive mesogenic compounds bearing PEO chains were doped with lithium salts. The physical characteristics of these hybrid materials have been investigated by optical microscopy, X-Ray diffraction and broadband dielectric spectroscopy. In particular, the ionic conductivity has been studied for two different anchoring conditions, i.e., planar and homeotropic. It is shown that the anisotropy of the liquid crystalline phase influences the ionic conductivity of the sample and thus the charge motion. Planar anchoring conditions provided the highest ionic conductivity. Then, the impact of UV irradiation on the molecular order has been investigated. Upon UV light, a Trans-Cis isomerisation mechanism of the azobenzene moieties present in the chore of the molecules takes places inducing the transformation of stick-like shape molecules (nematic phase) to chevron-like shape molecules (isotropic state). This phenomenon strongly affects the ionic conductivity evidencing the major role of the anisotropy on the conduction process. In order to investigate the dynamic properties of these systems under illumination a current/voltage study has also been carried out showing the potential use of these photosensitive mesogenic electrolytes as sensors. Finally, the LC phase has been stabilized by using a polymerization mechanism of photosensitive mesogenic monomers. It is interesting to point out that the fabricated gel exhibits enhanced electrical properties compared to that of the non-stabilized LC phase.LILLE1-Bib. Electronique (590099901) / SudocSudocFranceF

Late cortical disinhibition in focal hand dystonia

International audienc

Horizontally-aligned carbon nanotubes arrays and their interactions with liquid crystal molecules: Physical characteristics and display applications

We report on the physical characteristics of horizonthally-grown Single-Walled Carbon Nanotubes (h-al-SWNT) arrays and their potential use as transparent and conducting alignment layer for liquid crystals display devices. Microscopy (SEM and AFM), spectroscopic (Raman) and electrical investigations demonstrate the strong anisotropy of h-al-SWNT arrays. Optical measurements show that h-al-SWNTs are efficient alignment layers for Liquid Crystal (LC) molecules allowing the fabrication of optical wave plates. Interactions between h-al-SWNT arrays and LC molecules are also investigated evidencing the weak azimuthal anchoring energy at the interface, which, in turn, leads to LC devices with a high pretilt angle. The electro-optical reponses of h-al-SWNT/LC cells demonstrate that h-al-SWNT arrays are efficient nanostructured electrodes with potential use for the combined replacement of Indium Tin Oxyde and polymeric alignment layers in conventional displays

Parietomotor connectivity in the contralesional hemisphere after stroke: A paired-pulse TMS study

International audienc

Reconstruire le Nord – Pas-de-Calais après la Seconde Guerre mondiale (1944-1958)

De 1940 à la fin du second conflit mondial, le Nord et le Pas-de-Calais subissent plusieurs vagues de destruction. Reconstruire la région est un processus complexe, d'autant que la guerre aggrave une situation déjà difficile – dès 1939 de nombreuses villes nordistes avaient déjà besoin de se moderniser. Relever les ruines ne suffit pas, un immense effort d'édification d’infrastructures et de logements neufs s’impose. Cependant, les résultats d’une telle entreprise apparaissent mitigés : la lenteur de cette seconde Reconstruction condamne beaucoup d’habitants à vivre des années dans des bâtiments provisoires et de surcroît peu esthétiques. Faut-il réviser ce jugement stylistique ? Le bilan économique semble tout aussi incertain. Les défis étaient peut-être trop importants pour une région ravagée deux fois en une génération. Mais les principes adoptés pour le relèvement de l’économie ne portent-ils pas aussi leur part de responsabilité