Point defects in crystals occur when an atom is missing or is in an irregular position. After an initial skepticism, they spiked interest because of their possible applications as qubits in quantum computers. A strong and stable photoluminescence at room temperature (RT) and a single photon emission are the needed requirements. Point defects in hexagonal Boron Nitride(hBN) have been experimentally identified as RT stable single photon sources. In the photoluminescence spectrum of hBN there are different emission lines at transition energies ranging over the visible and the UV spectrum, and well-resolved phonon replica at lower energies. Whereas a considerable effort has been made so far and several color centers candidate have already been suggested, their exact nature remains uncertain. This project aims to solve some controversies related to the interpretation of defect related emission lines, with a special care for the study of the local vibrations at the origin of phonon replica.
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Venous thrombosis (VT) is the third leading cause of cardiovascular death in industrialized countries. Using a genome wide association study (GWAS) approach we have recently identified SLC44A2 as a new susceptibility gene for VT, the Arg154 isoform being associated with an increased risk. The SLC44A2 gene does not belong to the coagulation/fibrinolytic cascades and encodes choline transporter-like protein 2 (CTL2). Little is known about the function of CTL2. It has been associated with transfusion-related acute lung injury (TRALI), a process which involves activated neutrophils in a CTL2 isoform-dependent manner. In TRALI, alloantibodies react with the Arg154 (also called HNA-3a antigen), but not with the Gln154 (HNA-3b antigen). The direct binding of HNA-3a antibodies to HNA-3a+ neutrophils results in neutrophil activation and subsequent neutrophil-mediated destruction of pulmonary endothelial cells. The TRALI model, thought being different from VT physiopathology, paves the way to understand why SLCC44A2 plays a role in VT and why Arg154 isoform carriers have an increased risk of VT. The aim of the current project is to characterize the role of SLC44A2 in the physiopathology of VT using in-depth molecular functional studies. Given the increasing evidence of neutrophil involvement in VT physiopathology, we speculate that Arg154 isoform favors neutrophil adhesion and activation which in turn provides the initiating stimulus for VT development. To explain why the HNA-3a antigen associated with TRALI is also linked to an increased risk of VT, we made several assumptions based on 1) the receptor properties of CTL2 and 2) on the presence of CTL2 antibodies in blood circulation. We will characterize the interaction between CTL2 and von Willebrand factor (VWF), and how the polymorphism modulates this interaction. We will define the domain of interaction of VWF to CTL2 and elaborate potent modulating tools. For this, we will use human embryonic kidney cells (HEK-293 cell line) transfected to over-express either the CTL2/HNA-3a or the CTL2/HNA-3b isoform, in static and flow-based cell recruitment assays. Screening for anti-CTL2 autoantibodies will be performed in a large sample of individuals with VT from the EDITH case/control study. If present, antibodies from patients will be purified and they will be characterized. We will investigate the effects of the Arg154Gln polymorphism in vivo through work on SLC44A2 knock-out mice and the generation of knock-in mutant-mice. These humanized mice will be submitted to the most clinically relevant model of VT which consists in the partial ligation of the inferior vena cava. The development of the thrombus, the capacity of neutrophils to adhere to the venous endothelium and to become activated will be compared in the mice carrying either the CTL2/HNA-3a or CTL2/HNA-3b isoform. The capacity of NET release by activated neutrophils will also be compared. The present translational project is the transformation of omics data, obtained through the largest investigation to date of the influence of common genetic variations on VT risk by meta-analyzing 12 VT GWAS, into new ways of understanding, prediction (by identification and validation of new biomarkers) and treatment of patients with VT.
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The challenges of this project consist in simulating through laboratory experiments, the chemical evolution of interstellar ices, and grains to understand the evolution of the organic matter during the life cycle of interstellar grains. Currently, our team is developing two complementary approaches to study this evolution. First, we are investigating the chemical reactivity that can occur within analogs of pristine or cometary ices, by working on small size systems (two or three reactants). Second, we are investigating the characterization of refractory residues formed during photolysis and warming of ice analogs without any degradation using an orbitrap apparatus. We propose to develop a new approach, which consists in implementing an analytical system for the Volatile Analyses coming from the Heating of Interstellar Ice Analogs, the VAHIIA project. This new device will help us to get a better understanding of the chemical reactions that lead to the formation of refractory residues. It will also give crucial information on species that would sublimate during the warming of cometary nucleus. This system will consist in coupling to an ultra-high vacuum cryogenic system, a gas chromatography including a mass spectrometer in order to analyze gas species sublimating during the heating of ice analogs. Therefore, the VAHIIA project will be the missing link between the two existing projects, and the whole will provide a comprehensive experimental approach aiming to trace the chemical history of such analogs by studying the reactivity of ice at low temperature, analyzing the volatile species sublimating during the warming, and characterizing the non-volatile residues resulting from the latter. The VAHIIA project has been already submitted in 2011. The scientific program of the 2012 application is quite the same that of the previous application. The major modifications are present in the description by tasks of this application, and in the request resources. We call such funding for the purchase of the GC-MS device, and for a two years recruitment of a post-doctor, which objectives will be to participate in GC-MS development and analysis . Furthermore, a detail reply to the “retour au coordinateur” is given in section 3 of the annex document.
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To develop sustainable cities, urban mitigation policies reduced pollutant emissions and increased the number of vegetated areas to reduce urban heat islands, counteract carbon emissions, and improve air quality. But the impact of green infrastructures on secondary pollutants (formed in the air) remains poorly understood. Urban vegetated areas are a source of Biogenic Volatile Organic Compounds (BVOCs) that can react with the atmospheric oxidants, leading to the formation of Secondary Organic Aerosols (SOAs), one of the dominant fractions of atmospheric aerosols (particles suspended in air), that induce adverse health effects on human health. Currently, the impact of green infrastructures on SOAs is highly uncertain, because of the lack of knowledge regarding BVOC emissions from urban vegetated areas and the processes at the origin of SOA formation (in particular when mixed with anthropogenic emissions), pointing to urgent need for new studies on this topic. The general aim of VesPA (impact of Vegetated areas on Secondary Pollutants levels in urban Air) is to assess the contribution of vegetated urban areas to SOA levels in cities. This project will thus focus on SOA generated by BVOC emissions in urban areas through two main research tasks. The first one will characterize BVOC emissions from plant scale up to the district scale. The second task will investigate the reactivity and the potential SOA formation of these BVOC emissions, especially when they are mixed with anthropogenic VOCs. This original approach combines field and laboratory experiments, and will be developed in Marseilles, which gathers many advantages for the project. VeSPA will ultimately provide new knowledge to help developing future sustainable cities, in terms of urban air quality in the context of climate change.
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The HYDRAE project will explore the almost entirely unknown physical properties of neutral aromatic radicals, both in the isolated gas phase and in aggregates with solvent molecules. Dehydrogenated/ hydrogenated radicals intervene in all concerted Proton Coupled Electron Transfer (PCET) processes, which are the basis of many critical biological reactions. These species are also implicated in molecular hydrogen formation in the interstellar medium and in soot formation. We propose to study the UV-visible and IR spectroscopy of this largely unexplored class of molecular system, to determine the influence of heteroatoms or chemical functionalisation (amino, carbonyl, etc), size of the aromatic chromophore, and solvation upon the radical’s formation, structure and stability. These questions will be addressed by performing electronic spectroscopy and mass spectrometry on functionalised aromatic molecules in their (de)hydrogenated forms in a cryogenically-cooled ion trap or supersonic jet.
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