Unexpected De-Arylation of a Pentaaryl Fullerene

International audienceA triphenylamine-derived pentaaryl fullerene undergoes an unusual oxidative dearylation under basic conditions to give tetraarylated epoxy fullerene in high yield. The structure of the product was confirmed by single crystal X-ray diffraction. A mechanism is proposed to account for the loss of the addend and the subsequent formation of the epoxide group

Review of nanomaterial aging and transformations through the life cycle of nano-enhanced products

International audienceIn the context of assessing potential risks of engineered nanoparticles (ENPs), life cycle thinking can represent a holistic view on the impacts of ENPs through the entire value chain of nano-enhanced products from production, through use, and finally to disposal. Exposure to ENPs in consumer or environmental settings may either be to the original, pristine ENPs, or more likely, to ENPs that have been incorporated into products, released, aged and transformed. Here, key product-use related aging and transformation processes affecting ENPs are reviewed. The focus is on processes resulting in ENP release and on the transformation(s) the released particles undergo in the use and disposal phases of its product life cycle for several nanomaterials (Ag, ZnO, TiO 2 , carbon nanotubes, CeO 2 , SiO 2 etc.). These include photochemical transformations, oxidation and reduction, dissolution, precipitation , adsorption and desorption, combustion, abrasion and biotransformation, among other biogeochemical processes. To date, few studies have tried to establish what changes the ENPs undergo when they are incorporated into, and released from, products. As a result there is major uncertainty as to the state of many ENPs following their release because much of current testing on pristine ENPs may not be fully relevant for risk assessment purposes. The goal of this present review is therefore to use knowledge on the life cycle of nano-products to derive possible transformations common ENPs in nano-products may undergo based on how these products will be used by the consumer and eventually discarded. By determining specific gaps in knowledge of the ENP transformation process, this approach should prove useful in narrowing the number of physical experiments that need to be conducted and illuminate where more focused effort can be placed

Conception, synthèse et caractérisation de matériaux fluorescents pour l’élaboration d’uncapteur chimique d’explosifs

To be able to detect explosives ultra-traces has become a societal need particularly toanticipate terrorist attacks and for land mine detection. During the last decade, despite well studiedheavy analytical techniques, more sensitive, rapid and portable new chemical gas sensors havebeen developed. This thesis is devoted to the study of fluorescent organic materials used fornitroaromatics detection which appears among the most current explosives. Three objectivesconcern the present work: we have to design new sensitive materials towards nitroaromatics viafluorescence quenching, to develop a portable integrated sensor and to focus on the understandingof the detection process involved in nitroaromatics sensing. We explore the synthesis and the use ofnew alternate copolymers bearing fluorescent conjugated segments (phenyleneethynylene type) andchiral units with a C2 symmetry axis. This chiral unit is designed in order to avoid p-stacking betweenfluorophores. The effect of the conjugated segment nature and the type of chiral unit are studied inorder to obtain an optimal sensitivity. The interactions between nitroaromatics and sensitivefluorescent materials are also investigated. The deposition of alternate polymers leads tohomogeneous and smooth thin layers. Their good sensitivity and their excellent selectivity fornitroaromatics detection are well fitted for the development of chemical sensors. The result of thisleads to the development of a miniaturized integrated prototype of detection.Dans le cadre de la lutte antiterroriste, il est crucial d’être en mesure de détecter laprésence d’explosifs dans des lieux publics. De même, le déminage des anciennes zones de conflitsnécessite également de développer des outils adaptés à la détection d’explosifs. Cette thèse estconsacrée à l’étude de matériaux organiques fluorescents pour la détection de nitroaromatiques quifigurent parmi les explosifs les plus courants.L’objectif de cette thèse est triple puisqu’il s’agit à la fois de concevoir de nouveaux matériauxsensibles aux nitroaromatiques par inhibition de fluorescence, de développer un prototype et demieux cerner les mécanismes de détection des nitroaromatiques. Nous explorons la synthèse etl’utilisation de nouveaux co-polymères alternés comportant des segments conjugués fluorescents detype phénylèneéthynylène et des unités chirales possédant un axe de symétrie C2. La présence decette unité est susceptible de limiter les interactions p-p entre les fluorophores et de conférer aumatériau des propriétés adéquates. Dans le but d’obtenir une sensibilité optimale, nous étudionsl’incidence de la nature du segment conjugué d’une part et le type d’unité chirale d’autre part. Nousnous intéressons également aux interactions entre les nitroaromatiques et les matériaux sensibles.Les polymères alternés développés dans ce cadre conduisent à des dépôts homogènes etreproductibles. Leur bonne sensibilité et leur excellente sélectivité pour la détection desnitroaromatiques en fait d’excellents candidats pour la réalisation de capteurs. L’aboutissement dece travail de recherche est le développement d’un prototype de détection miniaturisé

The OASIS-Sustainable Nanomanufacturing Framework (OASIS-SNF): a new simplified approach to implement sustainable production in nanomanufacturing pilot lines and evaluate its sustainable manufacturing performance

The pilot production ecosystem deployed by the EU-project OASIS consists of 12 pilot lines (PLs) for the manufacture of nanomaterials, nano-intermediates and nano-enabled products, intended for the final production of lightweight multifunctional products, based on aluminium and polymer composites, for construction, energy, automotive and aeronautics. OASIS intends to deploy this nanomanufacturing ecosystem under a common umbrella of sustainable production, to ensure a future competitive, quality, safe and environmentally friendly production of nanoproducts, in compliance with the applicable regulation. This paper introduces the new OASIS-Sustainable Nanomanufaturing Framework (OASIS-SNF) and some first results obtained during the initial stages of deployment in the PLs (diagnostic and planning stages). The adoption of the OASIS-SNF among the OASIS PLs is intended to enable them to sustainable manufacturing their nanoproducts, properly manage their sustainability priorities, and continually improve their sustainability performance (management and results).The project OASIS received funding from the European Union’s Horizon 2020 research and innovation programme, under grant agreement Nº 814581. This paper reflects only the authors’ views, and the Commission is not responsible for any use that may be made of the information contained therein

In Vitro Dermal Safety Assessment of Silver Nanowires after Acute Exposure: Tissue vs. Cell Models

Silver nanowires (AgNW) are attractive materials that are anticipated to be incorporated into numerous consumer products such as textiles, touchscreen display, and medical devices that could be in direct contact with skin. There are very few studies on the cellular toxicity of AgNW and no studies that have specifically evaluated the potential toxicity from dermal exposure. To address this question, we investigated the dermal toxicity after acute exposure of polymer-coated AgNW with two sizes using two models, human primary keratinocytes and human reconstructed epidermis. In keratinocytes, AgNW are rapidly and massively internalized inside cells leading to dose-dependent cytotoxicity that was not due to Ag+ release. Analysing our data with different dose metrics, we propose that the number of NW is the most appropriate dose-metric for studies of AgNW toxicity. In reconstructed epidermis, the results of a standard in vitro skin irritation assay classified AgNW as non-irritant to skin and we found no evidence of penetration into the deeper layer of the epidermis. The findings show that healthy and intact epidermis provides an effective barrier for AgNW, although the study does not address potential transport through follicles or injured skin. The combined cell and tissue model approach used here is likely to provide an important methodology for assessing the risks for skin exposure to AgNW from consumer products

Macroscopic non-equilibrium thermodynamics in dynamic calorimetry

What is really measured in dynamic calorimetric experiments is still an open question. This paper is devoted to this question, which can be usefully envisaged by means of macroscopic non-equilibrium thermodynamics. From the pioneer work of De Donder on chemical reactions and with other authors along the 20th century, the question is tackled under an historical point of view. A special attention is paid about the notions of frequency dependent complex heat capacity and entropy production due to irreversible processes occurring during an experiment. This phenomenological approach based on thermodynamics, not widely spread in the literature of calorimetry, could open significant perspectives on the study of macro-systems undergoing physico-chemical transformations probed by dynamic calorimetry.Comment: review article (21 pages

Tau, prions and Aβ: the triad of neurodegeneration

This article highlights the features that connect prion diseases with other cerebral amyloidoses and how these relate to neurodegeneration, with focus on tau phosphorylation. It also discusses similarities between prion disease and Alzheimer’s disease: mechanisms of amyloid formation, neurotoxicity, pathways involved in triggering tau phosphorylation, links to cell cycle pathways and neuronal apoptosis. We review previous evidence of prion diseases triggering hyperphosphorylation of tau, and complement these findings with cases from our collection of genetic, sporadic and transmitted forms of prion diseases. This includes the novel finding that tau phosphorylation consistently occurs in sporadic CJD, in the absence of amyloid plaques

Measurement Methods for Nanoparticles in Indoor and Outdoor Air

International audienceA large variety of measurement methods for the characterization of airborne nanoparticles in indoor or outdoor air exist. The choice of an appropriate method depends strongly on the questions to be tackled. If the aerosol is to be characterized only for a single location, one may use stationary equipment that is rather bulky but provides the most details and is most accurate. Spatially resolved measurements can only be conducted with portable or personal measurement equipment which provide a limited dataset with lower accuracy. Furthermore, the metrics to be measured (e.g., number, surface area of mass concentration, chemical composition, etc.) determine the choice of measurement methods as no single method can do it all. Another determining factor is the time resolution of the instruments. While direct-reading monitors deliver the information with high time resolution (often 1 s) and hence allow for linking the measured concentration to certain activities, samplers collect the particles for subsequent analyses and therefore provide an average over the sampling time. Consequently, the choice of a measurement instrument for the characterization of airborne nanoparticles remains a compromise. In many practical applications, the combination of different techniques may be required

Conception, synthèse et caractérisation de matériaux fluorescents pour l'élaboration d'un capteur chimique d'explosifs

Dans le cadre de la lutte antiterroriste, il est crucial d'être en mesure de détecter la présence d'explosifs dans des lieux publics. De même, le déminage des anciennes zones de conflits nécessite également de développer des outils adaptés à la détection d'explosifs. Cette thèse est consacrée à l'étude de matériaux organiques fluorescents pour la détection de nitroaromatiques qui figurent parmi les explosifs les plus courants. L'objectif de cette thèse est triple puisqu'il s'agit à la fois de concevoir de nouveaux matériaux sensibles aux nitroaromatiques par inhibition de fluorescence, de développer un prototype et de mieux cerner les mécanismes de détection des nitroaromatiques. Nous explorons la synthèse et l'utilisation de nouveaux co-polymères alternés comportant des segments conjugués fluorescents de type phénylèneéthynylène et des unités chirales de possédant un axe de symétrie C2. La présence de cette unité est susceptible de limiter les interactions pi-pi entre les fluorophores et de conférer au matériau des propriétés adéquates. Dans le but d'obtenir une sensibilité optimale, nous étudions l'incidence de la nature du segment conjugué d'une part et le type d'unité chirale d'autre part. Nous nous intéressons également aux interactions entre les nitroaromatiques et les matériaux sensibles. Les polymères alternés développés dans ce cadre conduisent à des dépôts homogènes et reproductibles. Leur bonne sensibilité et leur excellente sélectivité pour la détection des nitroaromatiques en fait d'excellents candidats pour la réalisation de capteurs. L'aboutissement de ce travail de recherche est le développement d'un prototype de détection miniaturiséTo be able to detect explosives ultra-traces has become a societal need particularly to anticipate terrorist attacks and for land mine detection. During the last decade, despite well studied heavy analytical techniques, more sensitive, rapid and portable new chemical gas sensors have been developed. This thesis is devoted to the study of fluorescent organic materials used for nitroaromatics detection which appears among the most current explosives. Three objectives concern the present work: we have to design new sensitive materials towards nitroaromatics via fluorescence quenching, to develop a portable integrated sensor and to focus on the understanding of the detection process involved in nitroaromatics sensing. We explore the synthesis and the use of new alternate copolymers bearing fluorescent conjugated segments (phenyleneethynylene type) and chiral units with a C2 symmetry axis. This chiral unit is designed in order to avoid pi-stacking between fluorophores. The effect of the conjugated segment nature and the type of chiral unit are studied in order to obtain an optimal sensitivity. The interactions between nitroaromatics and sensitive fluorescent materials are also investigated. The deposition of alternate polymers leads to homogeneous and smooth thin layers. Their good sensitivity and their excellent selectivity for nitroaromatics detection are well fitted for the development of chemical sensors. The result of this leads to the development of a miniaturized integrated prototype of detectionMONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

New Chemically Functionalized Nanomaterials for Electrical Nerve Agents Sensors

A chemical receptor specific to traces of organophosphorus nerve agents (OPs) has been synthesized and grafted to carbon nanotubes and silicon nanowires in order to make electrical sensors. Our results show that it is possible to detect efficiently sub-ppm traces of OPs with excellent selectivity notably with the use of silicon nanowires by monitoring the Drain-Source current of the SiNW-FET at an optimum back Gate voltage as a function of time. First developments of a prototype have also been realized