Serum vitamin D status is associated with the presence but not the severity of primary open angle glaucoma.

OBJECTIVES: Vitamin D is involved in visual health and function. Our objective was to determine whether age-related vitamin D insufficiency was associated with the presence and the severity of primary open angle glaucoma (POAG) in a case-control study of older adults. STUDY DESIGN: Case-control study. MAIN OUTCOME MEASURES: One hundred fifty cases diagnosed with moderate-to-severe POAG (mean, 75.1±8.5 years; 42.0% female) and 164 healthy controls (mean, 73.0±7.9 years; 59.8% female) were included. POAG diagnosis was based on classical diagnostic criteria of optic nerve cupping and/or RNFL thinning, measured with optical coherence tomography. Severe POAG was defined as Humphrey visual field mean deviation (MD) worse than -12dB. Vitamin D insufficiency was defined as serum 25OHD≤75nmol/L. Age, gender, mean arterial pressure, vitamin D supplementation, visual acuity, and intraocular pressure were used as potential confounders. RESULTS: POAG cases had lower mean serum 25OHD concentration than controls (42.9±25.7nmol/L versus 49.4±29.5nmol/L, P=0.039) and a greater prevalence of vitamin D insufficiency (90.7% versus 82.3%, P=0.032). Increased mean serum 25OHD concentrations were associated with lower POAG frequency, even after adjustment for potential confounders (OR=0.89 per 10nmol/L of 25OHD, P=0.045). Similarly, vitamin D insufficiency was associated with POAG (OR=2.09, P=0.034). Among POAG cases, no 25OHD difference was observed between moderate and severe POAG cases (respectively, 39.2±23.3nmol/L versus 45.1±26.7nmol/L, P=0.188); and no between-group difference regarding the prevalence of vitamin D insufficiency (88.9% versus 94.0%, P=0.313). CONCLUSIONS: Decreased serum 25OHD concentration was associated with POAG. There was no 25OHD difference between moderate and severe POAG

Industry-Scale Orchestrated Federated Learning for Drug Discovery

To apply federated learning to drug discovery we developed a novel platform in the context of European Innovative Medicines Initiative (IMI) project MELLODDY (grant n{\deg}831472), which was comprised of 10 pharmaceutical companies, academic research labs, large industrial companies and startups. The MELLODDY platform was the first industry-scale platform to enable the creation of a global federated model for drug discovery without sharing the confidential data sets of the individual partners. The federated model was trained on the platform by aggregating the gradients of all contributing partners in a cryptographic, secure way following each training iteration. The platform was deployed on an Amazon Web Services (AWS) multi-account architecture running Kubernetes clusters in private subnets. Organisationally, the roles of the different partners were codified as different rights and permissions on the platform and administrated in a decentralized way. The MELLODDY platform generated new scientific discoveries which are described in a companion paper.Comment: 9 pages, 4 figures, to appear in AAAI-23 ([IAAI-23 track] Deployed Highly Innovative Applications of AI

CINETIQUE DE CROISSANCE DE NANOTUBES DE CARBONE MONO-PAROIS ET MULTI-PAROIS ORIENTES PAR PROCEDE PLASMA

This work deals with the growth of vertically oriented single- and multi-walled carbon nanotube by electron cyclotron resonance plasma enhanced chemical vapour deposition (ECR-PECVD). The growth kinetics of carbon nanotubes by PECVD have been investigated, highlighting some of the specific aspect of the plasma species on the single or few walled carbon nanotubes (SWNT/FWNT) growth. Controlling the main plasma parameters (plasma potential, gaseous precursor) and growth stages, we have demonstrated that vertically oriented and well separated SWNT or FWNT can be grown. We have demonstrated that such structures can be synthesized on aluminium substrate at temperature as low as 450°C. The cold emission measurements on the as-grown SWNT/FWNT show a relative low turn-on voltage (~5 V.µm-1), strongly dependent to the nanotubes morphology (length, radius). Nanotubes structural investigations have been conducted as a function of the growth conditions using several analysis, working at local scale (transmission electron microscopy, electron energy loss spectroscopy) as well as macroscopic scale (scanning electron microscopy, X-ray/ultraviolet photoelectron spectroscopy, elastic recoil detection analysis, Raman spectroscopy).Ce travail est consacré à la synthèse de nanotubes de carbone mono-parois et multi-parois orientés par dépôt chimique en phase vapeur assisté par plasma (PECVD). Des études cinétiques ont montré le rôle spécifique du plasma pour la croissance de nanotubes mono-parois (SWNT) ou possédant peu de parois (FWNT). En effet, les phénomènes de gravure physique et chimique, intrinsèques au procédé PECVD, favorisent la croissance des nanotubes multi-parois, structures plus robustes, au profit des SWNT/FWNT. En optimisant les paramètres du plasma (potentiel plasma, mélange des gaz) et le temps de dépôt, la croissance de SWNT/FWNT orientés peut être réalisée de manière contrôlée. De telles structures peuvent être obtenues à basse température (dès 450°C) sur des substrats recouverts d'aluminium. Les mesures d'émission par effet de champ des SWNT/FWNT orientés montrent des tensions de seuil peu élevées (~5 V.µm-1) corrélées avec la morphologie des nanotubes (longueur, rayon). De nombreuses techniques d'analyses ont été utilisées pour étudier la structure des nanotubes aussi bien à l'échelle locale (microscope électronique à transmission, spectroscopie de perte d'énergie des électrons) qu'à l'échelle macroscopique (microscope électronique à balayage, spectroscopie de photoélectrons ultraviolets/X, analyse par détection des atomes de recul, spectroscopie Raman)

Cinétique de croissance de nanotubes de carbone mono-parois et multi-parois orientés par procédé plasma

Ce travail est consacré à la synthèse de nanotubes de carbone mono-parois et multi-parois orientés par dépôt chimique en phase vapeur assisté par plasma (PECVD). Des études cinétiques ont montré le rôle spécifique du plasma pour la croissance de nanotubes mono paroi (SWNT) ou possédant peu de parois (FWNT). En effet, les phénomènes de gravure physique et chimique, intrinsèques au procédé PECVD, favorisent la croissance des nanotubes multi-parois, structures plus robustes, au profit des SWNT/FWNT. En optimisant les paramètres du plasma (potentiel plasma, mélange des gaz) et le temps de dépôt, la croissance de SWNT/FWNT orientés peut être réalisée de manière contrôlée. De telles structures peuvent être obtenue à basse température (dès 450C) sur des substrats recouverts d aluminium. Les mesures d émission par effet de champ des SWNT/FWNT orientés montrent des tensions de seuil peu élevées (~5 V. m-1) corrélées avec la morphologie des nanotubes (longueur, rayon). De nombreuses techniques d analyses ont été utilisées pour étudier la structure des nanotubes aussi bien à l échelle locale (microscope électronique à transmission, spectroscopie de perte d énergie) qu à l échelle macroscopique (microscope électronique à balayage, spectroscopie de photoélectrons ultraviolets/X, analyse par détection des atomes de recul, spectroscopie Raman).This work deals with the growth of vertically oriented single- and multi-walled carbon nanotube by electron cyclotron resonance plasma enhanced chemical vapour deposition (ECR-PECVD). The growth kinetics of carbon nanotubes by PECVD have been investigated, highlighting some of the specific aspects of the plasma species on the single or few walled carbon nanotubes (SWNT/FWNT) growth. Controlling the main plasma parameters (plasma potential, gaseous precursor) and growth stages, we have demonstrated that vertically oriented and well separated SWNT or FWNT can be grown. We have demonstrated that such structures can be synthesized on aluminium substrate at temperature as low as 450C. The cold emission measurements on the as-grown SWNT/FWNT show a relative low turn-on voltage (~5 V. m-1), strongly dependent to the nanotubes morphology (length, radius). Nanotubes structural investigations have been conducted as a function of the growth conditions using several analysis, working at local scale (transmission electron microscopy, electron energy loss spectroscopy) as well as macroscopic scale (scanning electron microscopy, X-ray/ultraviolet photoelectron spectroscopy, elastic recoil detection analysis, Raman spectroscopy).NANTES-BU Sciences (441092104) / SudocSudocFranceF

Multi-mode humidity sensitivity of carbon nanotubes field-effect transistors

Single-walled carbon nanotube-based field effect transistors have demonstrated highly promising gas sensing properties, especially a particularly strong sensitivity to humidity. The sensitivity to humidity impairs the use of the transistors in logic circuits, while the devices are usually very unstable as humidity sensors. The humidity dependence of electrical characteristics is generally attributed to charge trapping and water adsorption either on the oxide layer or on the nanotubes surface, but a detailed understanding of the mechanisms is prevented by the diversity of behaviors reported throughout the literature as well as by the response variability observed even with batch-fabricated samples [1]. We propose here a novel analysis of the different modes of humidity sensitivity in CNTFET based on a systematic, extensive multiparameter study of the electrical response of a series of CNTFET devices. We consider transistors whose channel consist in a network of mostly semiconducting, in-place CVD-grown SWNTs directly connecting source and drain electrodes [2], and we monitor systematically the characteristics of the transfer curves with respect to humidity in a metrological approach (Imax, Imin, threshold voltage, hysteresis voltage, subthreshold slope...). The significant variability of responses is interpreted using a compact-model-based approach [3]: we introduce a humidity-modulated voltage difference between effective gate voltage along the nanotube and imposed gate voltage. Using this approach, we rigorously interpret the variation of all the parameters while confirming the existence of two regimes, one at low humidity involving water molecules adsorption around charge trap, the other at high humidity involving a charging effect in the full layer of water molecules adsorbed on the oxide surface

Iron catalyst for the growth of carbon nanofibers: Fe, Fe3C or both?

International audienceIron is a widely used catalyst for the growth of carbon nanotubes (CNTs) or carbon nanofibers (CNFs) by catalytic chemical vapor deposition. However, both Fe and Fe-C compounds (generally, Fe3C) have been found to catalyze the growth of CNTs/CNFs, and a comparison study of their respective catalytic activities is still missing. Furthermore, the control of the crystal structure of iron-based catalysts, that is α-Fe or Fe3C, is still a challenge, which not only obscures our understanding of the growth mechanisms of CNTs/CNFs, but also complicates subsequent procedures, such as the removal of catalysts for better industrial applications. Here, we show a partial control of the phase of iron catalysts (α-Fe or Fe3C), obtained by varying the growth temperatures during the synthesis of carbon-based nanofibers/nanotubes in a plasma-enhanced chemical vapor deposition reactor. We also show that the structure of CNFs originating from Fe3C is bamboo-type, while that of CNFs originating from Fe is not. Moreover, we directly compare the growth rates of carbon-based nanofibers/nanotubes during the same experiments and find that CNFs/CNTs grown by α-Fe nanoparticles are longer than CNFs grown from Fe3C nanoparticles. The influence of the type of catalyst on the growth of CNFs is analyzed and the corresponding possible growth mechanisms, based on the different phases of the catalysts, are discussed