Peri-operative red blood cell transfusion in neonates and infants: NEonate and Children audiT of Anaesthesia pRactice IN Europe: A prospective European multicentre observational study

BACKGROUND: Little is known about current clinical practice concerning peri-operative red blood cell transfusion in neonates and small infants. Guidelines suggest transfusions based on haemoglobin thresholds ranging from 8.5 to 12 g dl-1, distinguishing between children from birth to day 7 (week 1), from day 8 to day 14 (week 2) or from day 15 (≥week 3) onwards. OBJECTIVE: To observe peri-operative red blood cell transfusion practice according to guidelines in relation to patient outcome. DESIGN: A multicentre observational study. SETTING: The NEonate-Children sTudy of Anaesthesia pRactice IN Europe (NECTARINE) trial recruited patients up to 60 weeks' postmenstrual age undergoing anaesthesia for surgical or diagnostic procedures from 165 centres in 31 European countries between March 2016 and January 2017. PATIENTS: The data included 5609 patients undergoing 6542 procedures. Inclusion criteria was a peri-operative red blood cell transfusion. MAIN OUTCOME MEASURES: The primary endpoint was the haemoglobin level triggering a transfusion for neonates in week 1, week 2 and week 3. Secondary endpoints were transfusion volumes, 'delta haemoglobin' (preprocedure - transfusion-triggering) and 30-day and 90-day morbidity and mortality. RESULTS: Peri-operative red blood cell transfusions were recorded during 447 procedures (6.9%). The median haemoglobin levels triggering a transfusion were 9.6 [IQR 8.7 to 10.9] g dl-1 for neonates in week 1, 9.6 [7.7 to 10.4] g dl-1 in week 2 and 8.0 [7.3 to 9.0] g dl-1 in week 3. The median transfusion volume was 17.1 [11.1 to 26.4] ml kg-1 with a median delta haemoglobin of 1.8 [0.0 to 3.6] g dl-1. Thirty-day morbidity was 47.8% with an overall mortality of 11.3%. CONCLUSIONS: Results indicate lower transfusion-triggering haemoglobin thresholds in clinical practice than suggested by current guidelines. The high morbidity and mortality of this NECTARINE sub-cohort calls for investigative action and evidence-based guidelines addressing peri-operative red blood cell transfusions strategies. TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT02350348

Electrodépôt en continu de polymères conducteurs sur des électrodes de tapis de nanotubes de carbone – Application aux pseudo-supercondensateurs

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Croissance en une seule étape de nanotubes de carbone verticalement alignés sur des feuilles d'aluminium

International audienceLes tapis de nanotubes de carbone verticalement alignés (VACNT) sont des matériaux aux propriétés structurales, électriques etthermiques très intéressantes pour de nombreuses applications. En particulier, leur croissance directe sur des feuilles ’aluminium est recherchée pour l’élaboration d’électrodes à faible résistance de contact applicables au domaine du stockage de l’énergie. Ledéveloppement industriel de ce type de produit passe par la mise au point d’un procédé de synthèse en continu, simple, peu couteux et transposable à grande échelle. La méthode de choix pour la synthèse de VACNT de haute qualité est le dépôt chimique en phase vapeur catalytique (CCVD). Plus précisément, le CCVD assisté par aérosol est un procédé à pression atmosphérique en une seule étape où le réacteur est alimenté en continu et simultanément par les précurseurs du carbone et du catalyseur métallique, et plus simple à mettre en œuvre à l'échelle industrielle que le procédé CCVD classique où les particules catalytiques sont préformées sur le substrat [Castro et al. Carbon 2013;61:585–94]. Il permet d'obtenir des tapis de VACNT de fortes épaisseur et vitesse de croissance à température modérée (> 750 °C) sur de nombreux substrats, y compris des substrats métalliques [Delmas et al. Nanotechnology 2012;23:105604]. Cependant, pour la croissance sur substrat en aluminium, il faut abaisser la température de synthèse sous son point de fusion (660 °C), ce qui a un impact sur la vitesse de croissance. Dans la littérature, le meilleur résultat obtenu avec le procédé en une seule étape est de l’ordre de 1µm/min seulement [Arcila-Velez et al. Nano Energy 2014;8:9–16]. Ici, nous montrons qu’il est possible d’améliorer considérablement les performances du procédé CCVD en une seule étape à basse température sur des feuilles d’Al de qualité industrielle et d’en faire le développement à grande échelle. Des tapis de VACNT jusqu'à 200 $\mu$m d'épaisseur sont obtenus à 615°C avec du ferrocène comme précurseur de catalyseur et de l'acétylène comme source de carbone. Les tapis sont propres (pureté 99.5%), bien alignés et denses (>10$^{11}$CNTs/cm$^2$) avec un diamètre de nanotube entre 8 et 12nm. L'analyse de l'interface VACNT/Al par microscopie électronique à transmission couplée à la dispersion d'énergie des rayons X permet de localiser les nanoparticules catalytiques à base de fer à la surface du substrat même après des synthèses de longue durée. Les mesures de voltampérométrie cyclique révèlent une accessibilité totale de la surface développée par les VACNT à l'électrolyte à base de liquides ioniques

Vertically aligned carbon nanotubes black coatings from roll-to- roll deposition process

International audienceVertically aligned carbon nanotubes (VACNTs) have recently attracted growing interest as a very efficient light absorbing material over a broad spectral range making them a superior coating in space optics applications such as radiometry, optical calibration, and stray light elimination. However, VACNT coatings available to-date most often result from batch-to-batch deposition processes thus potentially limiting the manufacturing repeatability, substrate size and cost efficiency of this material

Single-Step Synthesis of Vertically Aligned Carbon Nanotube Forest on Aluminium Foils

International audienceVertically aligned carbon nanotube (VACNT) forests are promising for supercapacitor electrodes, but their industrialisation requires a large-scale cost-effective synthesis process suitable to commercial aluminium (Al) foils, namely by operating at a low temperature (<660°C). We show that Aerosol-Assisted Catalytic Chemical Vapour Deposition (CCVD), a single-step roll-to-roll compatible process, can be optimised to meet this industrial requirement. With ferrocene as a catalyst precursor, acetylene as a carbon source and Ar/H$_2$ as a carrier gas, clean and dense forests of VACNTs of about 10 nm in diameter are obtained at 615°C with a growth rate up to 5 $\mu$m/min. Such novel potentiality of this one-step CCVD process is at the state-of-the-art of the multi-step assisted CCVD processes. To produce thick samples, long synthesis durations are required, but growth saturation occurs that is not associated with a diffusion phenomenon of iron in aluminium substrate. Sequential syntheses show that the saturation trend fits a model of catalytic nanoparticle deactivation that can be limited by decreasing acetylene flow, thus obtaining sample thickness up to 200 $\mu$m. Cyclic voltammetry measurements on binder-free VACNT/Al electrodes show that the CNT surface is fully accessible to the ionic liquid electrolyte, even in these dense VACNT forests

Electropolymerized poly(3-methylthiophene) onto high density vertically aligned carbon nanotubes directly grown on aluminum substrate: Application to electrochemical capacitors

International audiencePotentiostatic pulsed deposition of poly(3-methylthiophene) (P3MT) is carried out on vertically aligned carbon nanotubes directly grown on aluminum foil (VACNT/Al) in a mixture of ionic liquid in acetonitrile (25/75 v/v) as electrolyte to prepare pseudo-capacitive materials for electrochemical capacitors. VACNT with high density (2.1011 VACNT/cm2) and anisotropy, have high specific surface area (340 m2/g) and serve as template electrode to nanostructure the P3MT coating. The effect of the polymer weight in the nanocomposite on the morphology and electrochemical properties of nanocomposite electrodes is investigated. Up to 70% of P3MT is electrodeposited inside the carpet onto the VACNTs as evidenced by Scanning Electronic Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX). A specific capacitance of 170F/g was obtained for the optimal nanocomposite composition (70%). The calculated areal capacitance is 380 mF/cm2 and the volumetric capacitance is 76 F/cm3. In addition, nanostructured electrodes present an excellent stability and capacitance retention after 19,000 cycles. Finally, asymmetric electrochemical capacitors were assembled and specific energy of 52 Wh/kg (14 Wh/L) and a specific power of 10 kW/kg were obtained. A comparison with EDLC symmetric device highlights the role of P3MT to improve energy while maintaining a high power due to fast diffusion in the channels perpendicularly oriented to the substrate

P3MT/VACNT/Al Nanocomposites electrodes with high capacitance for supercapacitor

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VACNT growth on Aluminium: towards innovative supercapacitor nanocomposite electrodes

International audienceThe aim of this work is to develop innovative electrodes materials with high specific capacitance based on vertically aligned carbon nanotubes (VACNT) for supercapacitors. Catalytic chemical vapor deposition (CCVD) is one of the best method for VACNT growth. However considering the aluminium melting temperature (c.a. 660°C), the synthesis of VACNT on such substrates requires a significant reduction in the growth temperature as compared to conventional substrates. Our approach was first to identify the most relevant synthesis parameters to achieve VACNT growth at such a low temperature by using precursor mixtures more favourable for a decomposition at low temperature . Our results show that, with a single-step aerosol assisted CCVD process; it is possible to obtain clean, long and dense VACNTs on Al current collectors, with a growth rate at the best level of the state of the art at such low temperature. VACNT are then used to develop new pseudocapacitive electrode materials based on VACNT modified with Electronic Conducting Polymers (ECP) and/or metal oxide electrodeposited in a controlled manner . Nanocomposite electrodes of poly-3-methylthiophene (P3MT) in ionic liquid and manganese oxide in aqueous electrolytes both homogeneously deposited on VACNT have been elaborated and their storage properties determined. Finally, we select best nanocomposite configurations for electrodes upscaling demonstrating the industrial feasibility of the approach