25 research outputs found

    Elaboration and characterization of Fe1–xO thin films sputter deposited from magnetite target

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    Majority of the authors report elaboration of iron oxide thin films by reactive magnetron sputtering from an iron target with Ar–O2 gas mixture. Instead of using the reactive sputtering of a metallic target we report here the preparation of Fe1–xOthin films, directly sputtered froma magnetite target in a pure argon gas flow with a bias power applied. This oxide is generally obtained at very low partial oxygen pressure and high temperature.We showed that bias sputtering which can be controlled very easily can lead to reducing conditions during deposition of oxide thin film on simple glass substrates. The proportion of wustite was directly adjusted bymodifying the power of the substrate polarization. Atomic force microscopy was used to observe these nanostructured layers. Mössbauer measurements and electrical properties versus bias polarization and annealing temperature are also reported

    Exploring the selectivity and engineering potential of an NRPS condensation domain involved in the biosynthesis of the thermophilic siderophore fuscachelin

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    In nonribosomal peptide synthesis, condensation (C) domains are key catalytic domains that most commonly link carrier protein bound substrates to form peptides or depsipeptides. While adenylation domains have been well characterized due to their role in the selection of monomers and hence as gate keepers in nonribosomal peptide biosynthesis, C-domains have been the subject of debate as they do not have apparent “A-domain like” side chain selectivity for their acceptor substrates. To probe the selectivity and specificity of C-domains, here we report our biochemical and structural characterization of the C3-domain from the biosynthesis of the siderophore fusachelin. Our results show that this C-domain is not broadly flexible for monomers bearing significantly alternated side chains or backbones, which suggests there can be a need to consider C-domain specificity for acceptor substrates when undertaking NRPS engineering

    GNSS transpolar earth reflectometry exploriNg system (G-TERN): Mission concept

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    The global navigation satellite system (GNSS) Transpolar Earth Reflectometry exploriNg system (G-TERN) was proposed in response to ESA's Earth Explorer 9 revised call by a team of 33 multi-disciplinary scientists. The primary objective of the mission is to quantify at high spatio-temporal resolution crucial characteristics, processes and interactions between sea ice, and other Earth system components in order to advance the understanding and prediction of climate change and its impacts on the environment and society. The objective is articulated through three key questions. 1) In a rapidly changing Arctic regime and under the resilient Antarctic sea ice trend, how will highly dynamic forcings and couplings between the various components of the ocean, atmosphere, and cryosphere modify or influence the processes governing the characteristics of the sea ice cover (ice production, growth, deformation, and melt)? 2) What are the impacts of extreme events and feedback mechanisms on sea ice evolution? 3) What are the effects of the cryosphere behaviors, either rapidly changing or resiliently stable, on the global oceanic and atmospheric circulation and mid-latitude extreme events? To contribute answering these questions, G-TERN will measure key parameters of the sea ice, the oceans, and the atmosphere with frequent and dense coverage over polar areas, becoming a "dynamic mapper" of the ice conditions, the ice production, and the loss in multiple time and space scales, and surrounding environment. Over polar areas, the G-TERN will measure sea ice surface elevation (<10 cm precision), roughness, and polarimetry aspects at 30-km resolution and 3-days full coverage. G-TERN will implement the interferometric GNSS reflectometry concept, from a single satellite in near-polar orbit with capability for 12 simultaneous observations. Unlike currently orbiting GNSS reflectometry missions, the G-TERN uses the full GNSS available bandwidth to improve its ranging measurements. The lifetime would be 2025-2030 or optimally 2025-2035, covering key stages of the transition toward a nearly ice-free Arctic Ocean in summer. This paper describes the mission objectives, it reviews its measurement techniques, summarizes the suggested implementation, and finally, it estimates the expected performance

    Exploring the selectivity and engineering potential of an NRPS condensation domain involved in the biosynthesis of the thermophilic siderophore fuscachelin

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    In nonribosomal peptide synthesis, condensation (C) domains are key catalytic domains that most commonly link carrier protein bound substrates to form peptides or depsipeptides. While adenylation domains have been well characterized due to their role in the selection of monomers and hence as gate keepers in nonribosomal peptide biosynthesis, C-domains have been the subject of debate as they do not have apparent “A-domain like” side chain selectivity for their acceptor substrates. To probe the selectivity and specificity of C-domains, here we report our biochemical and structural characterization of the C3-domain from the biosynthesis of the siderophore fusachelin. Our results show that this C-domain is not broadly flexible for monomers bearing significantly alternated side chains or backbones, which suggests there can be a need to consider C-domain specificity for acceptor substrates when undertaking NRPS engineering

    Rapid Health and Needs assessments after disasters: a systematic review

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    <p>Abstract</p> <p>Background</p> <p>Publichealth care providers, stakeholders and policy makers request a rapid insight into health status and needs of the affected population after disasters. To our knowledge, there is no standardized rapid assessment tool for European countries. The aim of this article is to describe existing tools used internationally and analyze them for the development of a workable rapid assessment.</p> <p>Methods</p> <p>A review was conducted, including original studies concerning a rapid health and/or needs assessment. The studies used were published between 1980 and 2009. The electronic databasesof Medline, Embase, SciSearch and Psychinfo were used.</p> <p>Results</p> <p>Thirty-three studies were included for this review. The majority of the studies was of US origin and in most cases related to natural disasters, especially concerning the weather. In eighteen studies an assessment was conducted using a structured questionnaire, eleven studies used registries and four used both methods. Questionnaires were primarily used to asses the health needs, while data records were used to assess the health status of disaster victims.</p> <p>Conclusions</p> <p>Methods most commonly used were face to face interviews and data extracted from existing registries. Ideally, a rapid assessment tool is needed which does not add to the burden of disaster victims. In this perspective, the use of existing medical registries in combination with a brief questionnaire in the aftermath of disasters is the most promising. Since there is an increasing need for such a tool this approach needs further examination.</p

    Effect of synthesis method and morphology on the enhanced CO2 sensing properties of magnesium ferrite MgFe2O4

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    The synthesis and characterization of magnesium ferrite MgFe2O4 prepared by co-precipitation and sol gel combustion is reported. Structural characterization showed that all the samples have single spine! phase. The co precipitated sample exhibits smaller grains and twice higher BET surface than the sol gel combustion samples. The powder was shaped to dedicated chemo-resistive home-made sensors devices. The electrical properties and sensing properties towards carbon dioxide of both MgFe2O4 powders were studied. The type of cWar& crrieff were analysed on the basis of the change in resistance in the presence of air and argon. The sensing response towards CO2 was found to be dependent on the morphology of the powder sample and the CO2 concentration. A high response of 36% towards 5000 ppm of CO2 was reached which is good for this gas. The key role of the Mg ions modulating the electrical properties is discussed
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