Ref HAL: hal-03450520_v1
DOI: 10.1016/j.morpho.2021.05.006
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Ref HAL: hal-03450458_v1
DOI: 10.1101/2021.03.06.434049
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Abstract No curative treatment is available for any deficits induced by spinal cord injury (SCI). Following injury, microglia undergo highly diverse activation processes, including proliferation, and play a critical role on functional recovery. In a translational objective, we investigated whether a transient pharmacological reduction of microglia proliferation after injury is beneficial for functional recovery after SCI in mice and nonhuman primates. The colony stimulating factor-1 receptor (CSF1R) regulates proliferation, differentiation, and survival of microglia, we thus used an oral administration of GW2580, a CSF1R inhibitor. First, transient post-injury GW2580 administration in mice improves motor function recovery, promotes tissues preservation and/or reorganization (identified by coherent anti-stokes Raman scattering microscopy), and modulates glial reactivity. Second, post-injury GW2580-treatment in nonhuman primates reduces microglia proliferation, improves functional motor function recovery, and promotes tissue protection. Notably, three months after lesion microglia reactivity returned to baseline value. Finally, to initiate the investigation on molecular mechanisms induced by a transient post-SCI GW2580-treatment, we used microglia-specific transcriptomic analysis in mice. Notably, we detected a downregulation in the expression of inflammatory-associated genes and we identified genes that were up-regulated by SCI and further downregulated by the treatment. Thus, a transient oral GW2580 treatment post-injury may provide a promising therapeutic strategy for SCI patients and may also be extended to other central nervous system disorders displaying microglia activation.

Ref HAL: hal-03447203_v1
Ref Arxiv: 2105.03972
Ref. & Cit.: NASA ADS
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The efficiency of the adiabatic demagnetization of nuclear spin system (NSS) of a solid is limited, if quadrupole effects are present. Nevertheless, despite a considerable quadrupole interaction, recent experiments validated the thermodynamic description of the NSS in GaAs. This suggests that nuclear spin temperature can be used as the universal indicator of the NSS state in presence of external perturbations. We implement this idea by analyzing the modification of the NSS temperature in response to an oscillating magnetic field at various frequencies, an approach termed as the warm-up spectroscopy. It is tested in a n-GaAs sample where both mechanical strain and built-in electric field may contribute to the quadrupole splitting, yielding the parameters of electric field gradient tensors for 75As and both Ga isotopes, 69Ga and 71Ga.

Commentaires: 12 pages, 9 figures

Ref HAL: hal-03443023_v1
DOI: 10.3390/colloids5040051
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The binary phase diagram of γ-gliadin, a wheat storage protein, in water was explored thanks to the microevaporator, an original PDMS microfluidic device. This protein, usually qualified as insoluble in aqueous environments, displayed a partial solubility in water. Two liquid phases, a very dilute and a dense phase, were identified after a few hours of accumulation time in the microevaporator. This liquid–liquid phase separation (LLPS) was further characterized through in situ micro-Raman spectroscopy of the dilute and dense protein phases. Micro-Raman spectroscopy showed a specific orientation of phenylalanine residues perpendicular to the PDMS surfaces only for the diluted phase. This orientation was ascribed to the protein adsorption at interfaces, which would act as nuclei for the growth of dense phase in bulk. This study, thanks to the use of both aqueous solvent and a microevaporator, would provide some evidence for a possible physicochemical origin of the gliadin assembly in the endoplasmic reticulum of albumen cells, leading to the formation of dense phases called protein bodies. The microfluidic tool could be used also in food science to probe protein–protein interactions in order to build up phase diagrams

Ref HAL: hal-03442316_v1
Ref Arxiv: 2111.07581
Ref. & Cit.: NASA ADS
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HgTe quantum wells with a thickness of ${\sim}$7 nm may have a graphene-like band structure and have been recently proposed to be potential candidates for quantum Hall effect (QHE) resistance standards under the condition of operation in the fields above certain critical field $B_c$, above which the topological phase (with parasitic edge conduction) disappears. We present experimental studies of the magnetoresistance of different of HgTe quantum wells as a function temperature and magnetic field, determining the critical magnetic field $B_c$. We demonstrate that for QWs of specific width $B_c$ becomes low enough to grant observation of remarkably wide QHE plateaus at the filling factor ${v=-1}$ (holes) in relaxed cryomagnetic conditions: while using commercial 0.82 T Neodymium permanent magnets and temperature of a few Kelvin provided by ${^4He}$ liquid system only. Band structure calculations allow us to explain qualitatively observed phenomena due to the interplay between light holes and heavy holes energy sub-bands (side maxima of the valence band). Our work clearly shows that the peculiar band structure properties of HgTe QWs with massless Dirac fermions make them an ideal platform for developing metrological devices with relaxed cryomagnetic conditions.

Ref HAL: hal-03439383_v1
DOI: 10.3390/reactions2040030
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The functionalization of carbon nanotubes by polymers necessitates two steps, first their modification by oxidizing them or by covalently attaching small compounds to them, then the growth of the polymer chains from these anchors or their grafting onto them. In order to better control the process and the rate of functionalization, we develop polymers able to covalently react with the carbon nanotubes by their side chains in one step. We describe the synthesis of a copolymer of dodecylthiophene and its analogue bearing an aniline group at the end of the dodecyl side chain. This copolymer can functionalize single-walled carbon nanotubes (SWNTs) non-covalently and disperse more SWNTs than its hexyl analogues. UV-Vis and fluorescence spectroscopies show that in these non-covalent hybrids, the polymer forms p-stacked aggregates on the SWNTs. The non-covalent hybrids can be transformed into covalent ones by diazonium coupling. In these covalent hybrids the polymer is no longer p-stacked. According to Raman spectroscopy, the conformation of the poly(3-hexylthiophene) backbone is more ordered in the non-covalent hybrids than in the covalent ones.

Ref HAL: hal-03428861_v1
DOI: 10.1088/2040-8986/ac253d
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The possibility of amplification of the coupled plasmon-optical phonon (LO) mode in HgTe quantum wells (QWs) is theoretically considered assuming an inverted band population. We calculate the dispersion of the plasmon-LO modes taking into account the spatial dispersion of the electronic polarizability. It is shown that stimulated emission of the plasmon-LO mode is possible in the frequency range corresponding to the Reststrahlen band of GaAs both in a 6-nm-wide HgTe/CdTe QW and in a 5-nm-wide HgTe/Cd 0.7 Hg 0.3 Te QW grown on the (013) plane. Due to the anisotropy of the dispersion law for the plasmon-LO mode, the [03-1] direction appears to be optimal for generation.