179 research outputs found

    Facile synthesis and optical properties of extended TPA-Benzodifuran derivatives connected by cyano-vinylene junctions

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    Two new conjugated molecules based on triphenylamine – benzo[1,2-b:4,5-b’]difuran moieties and integrating cyanovinyl bonds have been synthesized by using the new benzodifuran-acetonitrile synthon, easily and rapidly prepared in two steps from 2,2’-(2,5-dihydroxy-1,4-phenylene)diacetic acid. The electronic properties of the molecules were analysed by UV-Vis absorption and emission spectroscopies and cyclic voltammetry. The potential use of the molecules as donor materials for photovoltaic conversion were evaluated in simple bilayer solar cells using C60 as the acceptor materials. The comparison between the two derivatives reveals that the extension of the conjugated system with the insertion of furan cycles leads to a narrowing band gap, a better emission property, a direct access to dication state and an enhancement of the photovoltaic characteristics

    Rational Topological Design for Fluorescence Enhancement upon Aggregation of Distyrylfuran Derivatives

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    A series of 2,5-distyrylfuran derivatives bearing pentafluorophenyl- and cyanovinyl units have been synthesized for aggregation-induced emission (AIE). The effect of the type and extent of the supramolecular connections on the AIE of the furan derivatives were examined and correlated with their X-ray crystal structures. It was found that the simultaneous presence of cyano and perfluorophenyl units strongly enhances the fluorescence upon aggregation. Single-crystal X-ray diffraction analysis confirmed that C — H⋅⋅⋅F, F⋅⋅⋅F, C — H⋅⋅⋅nitrile, Ar⋅⋅⋅ArF (Ar=aryl, ArF=fluoroaryl), and nitrile⋅⋅⋅ArF intra- and intermolecular interactions drive the topology of the molecule and that solid-state supramolecular contacts favor AIE of the furan derivatives

    Étude exploratoire des caractéristiques professionnelles d'un échantillon de suicidants hospitalisés

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    Cette étude a pour objectif de décrire les caractéristiques professionnelles d’un échantillon de suicidants. Un enquêteur a interrogé les suicidants âgés de 18 à 65 ans, hospitalisés consécutivement dans une unité spécialisée du CHU d’Angers sur une durée de 6 mois et demi. Au total, 87 suicidants actifs avec un emploi ont été interrogés. Ils ont souvent été confrontés à des contraintes organisationnelles décrites dans la littérature comme responsables de souffrance mentale liée au travail. Cela concerne globalement autant les hommes que les femmes. En comparaison aux enquêtes de santé au travail (Sumer, Samotrace…), les suicidants sont plus nombreux à ressentir entre autres un stress intense au travail, une conscience professionnelle heurtée et à être en situation tendue selon le modèle de Karasek. Cela pourrait être en faveur d’un lien entre les tentatives de suicide et certains facteurs de pénibilité mentale au travail. Les résultats de cette étude sont à interpréter avec prudence du fait des phénomènes de circularité des données et de la faiblesse de l’échantillon

    Etchant-induced shaping of nanoparticle catalysts during chemical vapour growth of carbon nanofibres

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    10 pagesInternational audienceCarbon nanofibres (CNFs) obtained by plasma enhanced chemical vapour deposition are made of cone-shaped graphene layers, the opening angle of which has a significant influence on their properties: the smaller the angle, the closer the properties to those of carbon nanotubes. That angle is determined by the shape of the metal nanoparticle used to catalyse the growth. We show in this paper that the shape of Ni nanoparticle catalysts, and in turn the CNF properties, can be tuned during plasma-enhanced chemical vapour deposition, by the choice of the etchant gas. We show in particular that a water-containing etchant (H2O or H2O+H2) increases the growth rate by an order of magnitude at 600°C compared to an ammonia-containing etchant (NH3 or NH3+H2), and leaves more elongated Ni particles with a cone angle three times smaller. We conclude that the cone angle and the growth rate are directly related, and propose a mechanism to explain that large difference between the two etchants

    Theory of Mind and Empathy in Preclinical and Clinical Huntington's Disease

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    We investigated cognitive and affective Theory of Mind (ToM) and empathy in patients with premanifest and manifest Huntington\u27s disease (HD). The relation between ToM performance and executive skills was also examined. 16 preclinical and 23 clinical HD patients, and 39 healthy subjects divided in 2 control groups were given a French adaptation of the Yoni test (Shamay-Tsoory and Aharon-Peretz, 2007) that examines first and second-order cognitive and affective ToM processing in separate conditions with a physical control condition. Participants were also given questionnaires of empathy and cognitive tests which mainly assessed executive functions (inhibition and mental flexibility). Clinical HD patients made significantly more errors than their controls in the first-and second-order cognitive and affective ToM conditions of the Yoni task, but exhibited no empathy deficits. However, there was no evidence that ToM impairment was related to cognitive deficits in these patients. Preclinical HD patients were unimpaired in ToM tasks and empathy measures compared to their controls. Our results are consistent with the idea that impaired affective and cognitive mentalising emerges with the clinical manifestation of HD, but is not necessarily part of the preclinical stage. Furthermore, these impairments appear independent of executive dysfunction and empathy

    L’anesthésie topique sans recours à un médecin anesthésiste dans la chirurgie de la cataracte ambulatoire de l’adulte : évaluation des critères de sélection en consultation, à propos de 248 cas

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    INTRODUCTION: This work aims to evaluate selection criteria used during the cataract surgery scheduling visit, to choose whether or not there will be an anesthesiologist available during the surgery, depending upon the patient\u27s comorbidities. MATERIALS AND METHODS: Retrospective study performed in 2016 in Angers university medical center. Two groups were established on the cataract surgery scheduling visit, based on patients\u27 comorbidities and vital signs (blood pressure, heart rate). One group of patients were operated with topical anesthesia, with the anesthesia team, the other one only with blood pressure and heart rate monitoring, with, if needed, a written protocol of sedation or blood pressure control, which could be administrated by a circulating nurse. Those two groups were compared in terms of postoperative complications, intraoperative pain and postoperative visual acuity. RESULTS: 248 surgeries were performed on 185 individual patients, with 108 under stand-alone topical anesthesia, and 135 under anesthetist-monitored topical anesthesia. No significant difference was demonstrated between the two groups, in terms of complications, intraoperative pain or visual acuity outcomes. DISCUSSION: This study allows us to assess selection criteria used in our hospital to determine which patients can undergo cataract surgery under topical anesthesia without the anesthesia team. This procedure lowers organizational constraints while still insuring patient safety. Some patients still probably need an anesthesiologist present, such as those with an unstable disease or risk of agitation, in order to optimize the medications administered during surgery

    Preparation of New Polyols Based on Cis-1,4-Polyisoprene by Using 1,3-Dipolar Cycloaddition

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    This research focuses on synthesis and modification of polyol precursors derived from cis-1,4-polyisoprene (PI). These new polyol precursors can be converted to high value-added polyurethane (PU). The epoxidized hydroxytelechelic PI (EHTPI) prepared by chemical modification from PI was used as starting material for polyol synthesis. 1,3-Dipolar cycloaddition between a terminal alkyne and an azide has rapidly become the most popular click reaction. We applied this reaction to couple azide-functionalized PI and alkyne-functionalized sugar for preparing polyols. For azide functionalization, 1-methyl epoxidized cyclohexane was used as a model molecule, and various conditions for epoxide ring opening of 1-methyl epoxidized cyclohexane and EHTPI were investigated. The cycloaddition of alkyne and azide was carried out in the presence of sodium ascorbate and copper sulfate. The polyol precursors obtained might be used to prepare biodegradable polyol PU

    Toward sustainable organic semiconductors from a broad palette of green reactions

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    New conjugated materials, based on the triphenylamine-thiophene moiety and integrating azomethine bonds with a dibenzofuran unit or a cyanovinyl bond with a phenylthiophene or bithiophene unit, have been synthesized by using a wide range of green reactions such as direct heteroarylation coupling reactions, Knoevenagel and Schiff-base condensations and Stille cross-coupling reactions using ionic-liquid-supported thiophenylstannane. The electronic properties of the new molecules were analyzed by UV/Vis spectroscopy and cyclic voltammetry. The potential use of the molecules as donor materials for photovoltaic conversion were evaluated in simple bilayer solar cells using C60 as the acceptor material

    Hydrofoil Configurations for Sailing Superyachts: Hydrodynamics, Stability and Performance

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    Hydrofoil-assisted racing monohulls have undergone significant development phases in the past decade, yet very little scientific data has reached the public domain: an increasingly critical issue as the superyacht industry is now looking at the implementation of foils onto leisure vessels. Consequently, three contemporary configurations, namely a Dynamic Stability System, a Dali-Moustache and a Chistera have been towing tank tested to present the first complete characterisation of the hydrodynamic efficiency, quantification of the added dynamic stability and eventually the resulting impact on sailing performance. Furthermore, the considerations inherent to the design and installation of hydrofoils onto superyachts will be detailed. Building on extensive experimental work, this paper provides a comprehensive assessment of current design options with both technical and practical guidelines and recommendations to improve performance
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