1,518 research outputs found

    Pelagic fish stock assessment by acoustic methods at Ifremer

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    Crude oil to chemicals: light olefins from crude oil

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    [EN] The possibility to fulfill the increasing market demand and producers' needs in processing crude oil, a cheap and universally available feedstock, to produce petrochemicals appears to be a very attractive strategy. Indeed, many petrochemicals are produced as side streams during crude oil refining, which primary goal remains transportation fuel production. Availability of some critical feedstocks may then depend on local refining policy. In order to improve flexibility, it has been proposed to directly crack crude oil to produce petrochemicals, in particular light olefins (ethylene, propylene, butenes), using technologies derived from fluid catalytic cracking. This paper attempts to review the main research works done on the topic in the literature in the last five decades, focussing on process as well as catalyst technology, with a special interest for fluid catalytic cracking (FCC) based technology that can be used towards maximizing chemicals from crude oil. Factors investigated include use of severe cracking conditions, on-purpose additives (from ZSM5 to more exotic, metal doped additives), recycle streams and multiple riser systems.The authors thank Saudi Aramco for material and financial support. Financial support by the Spanish Government-MINECO through program "Severo Ochoa" (SEV 2012-0267), Consolider Ingenio (2010-Multicat, CSD-2009-0050), MAT2012-31657, CTQ2015-70126-R (MINECO/FEDER), by the European Union through ERC-AdG-2014-671093-SynCatMatch and by the Generalitat Valenciana through the Prometeo program (PROMETEOII/2013/011) is also acknowledged.Corma Canós, A.; Corresa Mateu, E.; Mathieu ., Y.; Sauvanaud ., LL.; Al-Bogami, S.; Al-Ghrami, M.; Bourane, A. (2017). Crude oil to chemicals: light olefins from crude oil. Catalysis Science & Technology. 7(1):12-46. https://doi.org/10.1039/c6cy01886fS12467

    Halophilic Actinomycetes in 1 Saharan Soils of Algeria: Isolation, Taxonomy and Antagonistic Properties

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    The diversity of a population of 52 halophilic actinomycetes was evaluated by a polyphasic approach, which showed the presence of Actinopolyspora, Nocardiopsis, Saccharomonospora, Streptomonospora and Saccharopolyspora genera. One strain was considered to be a new member of the last genus and several other strains seem to be new species. Furthermore, 50% of strains were active against a broad range of indicators and contained genes encoding polyketide synthetases and nonribosomal peptide synthetases

    During vertebrate development, arteries exert a morphological control over the venous pattern through physical factors

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    The adult vasculature is comprised of three distinct compartments: the arteries, which carry blood away from the heart and display a divergent flow pattern; the capillaries, where oxygen and nutrient delivery from blood to tissues, as well as metabolic waste removal, occurs; and the veins, which carry blood back to the heart and are characterized by a convergent flow pattern. These compartments are organized in series as regard to flow, which proceeds from the upstream arteries to the downstream veins through the capillaries. However, the spatial organization is more complex, as veins may often be found paralleling the arteries. The factors that control the morphogenesis of this hierarchically branched vascular network are not well characterized. Here, we explain how arteries exert a morphological control on the venous pattern. Indeed, during vertebrate development, the following transition may be observed in the spatial organization of the vascular system: veins first develop in series with the arteries, the arterial and venous territories being clearly distinct in space (cis-cis configuration). But after some time, new veins grow parallel to the existing arteries, and the arterial and venous territories become overlapped, with extensive and complex intercalation and interdigitation. Using physical arguments, backed up by experimental evidence (biological data from the literature and in situ optical and mechanical measurements of the chick embryo yolk-sac and midbrain developing vasculatures), we explain how such a transition is possible and why it may be expected with generality, as organisms grow. The origin of this transition lies in the remodeling of the capillary tissue in the vicinity of the growing arteries. This remodeling lays down a prepattern for further venous growth, parallel to the existing arterial pattern. Accounting for the influence of tissue growth, we show that this prepatterned path becomes favored as the body extends. As a consequence, a second flow route with veins paralleling the arteries (cis-trans configuration) emerges when the tissue extends. Between the cis-cis and cis-trans configurations, all configurations are in principle possible, and self-organization of the vessels contributes to determining their exact pattern. However, the global aspect depends on the size at which the growth stops and on the growth rate

    Measurement of Spin Density Matrix Elements in Λ(1520) Photoproduction at 8.2-8.8 GeV

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    We report on the measurement of spin density matrix elements of the Λ(1520) in the photoproduction reaction γp→Λ(1520)K+, via its subsequent decay to K−p. The measurement was performed as part of the GlueX experimental program in Hall D at Jefferson Laboratory using a linearly polarized photon beam with Eγ = 8.2 GeV–8.8 GeV. These are the first such measurements in this photon energy range. Results are presented in bins of momentum transfer squared, − (t − t0). We compare the results with a Reggeon exchange model and determine that natural exchange amplitudes are dominant in Λ(1520) photoproduction

    Comparison of serious inhaler technique errors made by device-naïve patients using three different dry powder inhalers: a randomised, crossover, open-label study

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    Background: Serious inhaler technique errors can impair drug delivery to the lungs. This randomised, crossover, open-label study evaluated the proportion of patients making predefined serious errors with Pulmojet compared with Diskus and Turbohaler dry powder inhalers. Methods: Patients ≥18 years old with asthma and/or COPD who were current users of an inhaler but naïve to the study devices were assigned to inhaler technique assessment on Pulmojet and either Diskus or Turbohaler in a randomised order. Patients inhaled through empty devices after reading the patient information leaflet. If serious errors potentially affecting dose delivery were recorded, they repeated the inhalations after watching a training video. Inhaler technique was assessed by a trained nurse observer and an electronic inhalation profile recorder. Results: Baseline patient characteristics were similar between randomisation arms for the Pulmojet-Diskus (n = 277) and Pulmojet-Turbohaler (n = 144) comparisons. Non-inferiority in the proportions of patients recording no nurse-observed serious errors was demonstrated for both Pulmojet versus Diskus, and Pulmojet versus Turbohaler; therefore, superiority was tested. Patients were significantly less likely to make ≥1 nurse-observed serious errors using Pulmojet compared with Diskus (odds ratio, 0.31; 95 % CI, 0.19–0.51) or Pulmojet compared with Turbohaler (0.23; 0.12–0.44) after reading the patient information leaflet with additional video instruction, if required. Conclusions These results suggest Pulmojet is easier to learn to use correctly than the Turbohaler or Diskus for current inhaler users switching to a new dry powder inhaler

    Direct crude oil cracking for producing chemicals: Thermal cracking modeling

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    [EN] The direct cracking of crude oil is an interesting option for producing cheaply large amounts of petrochemicals. This may be carried out with catalyst and equipment similar to that of catalytic cracking, but at a temperature range between that of standard catalytic cracking and steam cracking. Thermal cracking will play a role in the conversion, but is rarely disclosed in experimental or modeling work. Thus, a crude oil and its fractions were thermally cracked and the products yields were modeled using a 9 lumps cracking scheme. It was found that heavy fraction cracks twice as fast as diesel fraction and ten times faster than gasoline fraction, with activation energies in the 140-200 kJ/mol range. Selectivity to ethylene, propylene and butenes were found similar in the operating range explored.The authors thank Saudi Aramco for its material and financial support. Financial support by the Spanish Government-MINECO through programs "Severo Ochoa" (SEV 2012-0267) and CTQ2015-70126-R and by the Generalitat Valenciana through the Prometeo program (PROMETEOII/2013/011) is also acknowledged.Corma Canós, A.; Sauvanaud, LL.; Mathieu, Y.; Al-Bogami, S.; Bourane, A.; Al-Ghrami, M. (2018). Direct crude oil cracking for producing chemicals: Thermal cracking modeling. Fuel. 211:726-736. https://doi.org/10.1016/j.fuel.2017.09.099S72673621
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