Few layers graphene on 6H-SiC(000-1): an STM study

We have analyzed by Scanning Tunnelling Microscopy (STM) thin films made of few (3-5) graphene layers grown on the C terminated face of 6H-SiC in order to identify the nature of the azimuthal disorder reported in this material. We observe superstructures which are interpreted as Moir\'e patterns due to a misorientation angle between consecutive layers. The presence of stacking faults is expected to lead to electronic properties reminiscent of single layer graphene even for multilayer samples. Our results indicate that this apparent electronic decoupling of the layers can show up in STM data.Comment: 20 page

Electronic structure of epitaxial graphene layers on SiC: effect of the substrate

Recent transport measurements on thin graphite films grown on SiC show large coherence lengths and anomalous integer quantum Hall effects expected for isolated graphene sheets. This is the case eventhough the layer-substrate epitaxy of these films implies a strong interface bond that should induce perturbations in the graphene electronic structure. Our DFT calculations confirm this strong substrate-graphite bond in the first adsorbed carbon layer that prevents any graphitic electronic properties for this layer. However, the graphitic nature of the film is recovered by the second and third absorbed layers. This effect is seen in both the (0001)and $(000\bar{1})$ 4H SiC surfaces. We also present evidence of a charge transfer that depends on the interface geometry. It causes the graphene to be doped and gives rise to a gap opening at the Dirac point after 3 carbon layers are deposited in agreement with recent ARPES experiments (T.Ohta et al, Science {\bf 313} (2006) 951)

A new 3MW ECRH system at 105 GHz for WEST

The aim of the WEST experiments is to master long plasma pulses (1000s) and expose ITER-like tungsten wall to deposited heat fluxes up to 10 MW/m$^2$. To increase the margin to reach the H-Mode and to control W-impurities in the plasma, the installation of an upgraded ECRH heating system, with a gyrotron performance of 1MW/1000s per unit, is planned in 2023. With the modifications of Tore Supra to WEST, simulations at a magnetic field B$_0$∼3.7T and a central density n$_{e0}$∼6 × 10$^{19}$ m$^{−3}$ show that the optimal frequency for central absorption is 105 GHz. For this purpose, a 105 GHz/1MW gyrotron (TH1511) has been designed at KIT in 2021, based on the technological design of the 140 GHz/1.5 MW (TH1507U) gyrotron for W7-X. Currently, three units are under fabrication at THALES. In the first phase of the project, some of the previous Tore Supra Electron Cyclotron (EC) system components will be re-installed and re-used whenever possible. This paper describes the studies performed to adapt the new ECRH system to 105 GHz and the status of the modifications necessary to re-start the system with a challenging schedule

miR-16 (ses fonctions et son implication dans les hémopathies malignes)

The microARN (miRNAs), products of genes mir constitute a class of small non-coding RNA of 18-24nt present in most live species. They are involved in post-transcriptional control of gene expression by interfering with the stability of mRNA or acting as translational repressors. Numerous studies have shown that miRNAs acting on mRNA coding for proteins involved in controlling the development and other important biological functions in plants and animals. Data from the literature suggest that mir genes are target genes of the tumoral process, particularly in the model of B cells chronic lymphocytic leukemia (B-CLL) where a deletion of genes miR-15 and miR-16 is frequent. To clarify the role of miRNAs in lymphoid tumorogenesis, we analyzed the expression of miR-16 in a series of childhood acute lymphoblastic leukemia. We showed a prognostic value of miR-16 in this pathology with better prognosis at low levels of miR-16. We have also developed an approach that has enabled us to identified two potential targets of miR-16, the mRNA coding for caprin-1 and HMGA1 proteins which are involved in cell activation and chromatin architecture, respectively. In addition, we confirmed the inhibition of cyclin E by miR-16 epression and we studied the diminution of its mRNA half-life by miR-16 overexpression in HeLa cell line. In conclusion, this work enabled us to introduce some elements that should offer a better understanding of the role of miRNAs in normal cell and in the physiopathology of lymphoid tumorsLYON1-BU.Sciences (692662101) / SudocSudocFranceF

Etudes des relations des protéines BTG/APRO avec leurs partenaires CAF1 et PRMT1

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

In search of a function for the TIS21/PC3/BTG1/TOB family

International audienc

Vers la thérapie génique de la drépanocytose (description et évaluation d'un modèle de cellules hématopoïétiques primitives humaines permettant d'étudier le transfert de gène rétroviral de la b-globine dans leur descendance érythtoïde)

La drépanocytose est une maladie héréditaire monogénique de la b-globine, pour laquelle il n'existe aucun traitement éradicateur en dehors de l'allogreffe de cellules souches hématopoïétiques, lorsqu'elle est possible. Une thérapeutique par thérapie génique de cette maladie est proposée. Dans ce contexte, nous avons développé un modèle permettant d'étudier l'érythropoïèse humaine, in vitro et in vivo (souris NOD/SCID ou b2 microglobuline"nulles" NOD/SCID), ainsi que ses modifications après transfert rétroviral de la b-globine dans les cellules souches hématopoïétiques humaines parentales. Nous avons pu démontrer que le foie foetal humain contenait un grand nombre de cellules hématopoïétiques primitives (LTC-IC, CFU-GEMM et CRU) et différenciées (CFU-GM, CFU-MK, BFU-E, érythroblastes), par comparaison à d'autres sources cellulaires plus tardives. En outre, les capacités du foie foetal humain à produire in vivo des cellules érythroïdes matures et immatures (LTC-IC, CD34+38- et CRU), sont supérieurs à celles observées avec le sang de cordon et la moelle osseuse adulte. Ces propriétés uniques ont été exploitées dans un second volet où l'on a transféré in vitro, par rétrovirus, le gène de la b-globine humaine (+HS-2), couplé à la GFP dans les cellules hématopoïétiques primitives (LTC-IC et CRU) de foie foetal humain et de sang de cordon ombilical, et obtenu l'expression du transgène (au niveau de l'ARN messager), dans les cellules érythroïdes matures générées in vivo et régénérées in vivo. Nous avons enfin détaillé les caractéristiques fonctionnelles des LTC-IC du sang périphérique de patients drépanocytaires, pouvant éventuellement représenter une population cellulaire cible de choix pour transfert du gène de la b-globine, dans un système autologue. Le succès récent de notre groupe dans le traitement de deux modèles de souris transgéniques drépanocytaires, au moyen de vecteurs lentiviraux (R.Pawliuk et coll., Science, 2001; 294; 2368-2371), ouvre de nouvelles perspectives intéressantes quant au traitement de le maladie humaine par transfert de gènes.LYON1-BU.Sciences (692662101) / SudocSudocFranceF

The specific activation of gadd45 following UVB radiation requires the POU family gene product N-oct3 in human melanoma cells

International audienc

Stimulation of Avian Myoblast Differentiation by Triiodothyronine: Possible Involvement of the cAMP Pathway

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Ripples in epitaxial graphene on the Si-terminated SiC (0001) surface

International audienceInteraction with a substrate can modify the graphene honeycomb lattice and thus alter its out- standing properties. This could be particularly true for epitaxial graphene where the carbon layers are grown from the SiC substrate. Extensive ab initio calculations supported by Scanning Tunneling Microscopy experiments demonstrate here that the substrate indeed induces a strong nanostruc- turation of the interface carbon layer. It generates an apparent 6x6 modulation different from the interface 6√3×6√3R30 symmetry used for the calculation. The top carbon layer roughly follows the interface layer morphology. This creates soft 6x6 ripples in the otherwise graphene-like hon- eycomb lattice. The wavelength and height of the ripples are much smaller than the one found in exfoliated graphene. Their formation mechanism also differs: They are due to the weak interaction with the interface layer and not to a roughening of the plane due to the instability of a strictly two-dimensional crystal