679 research outputs found

    Utilisation du limonène comme synthon agrochimique pour la synthèse et l'extraction de produits naturels

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    The objective of this study was to transform limonene as an agro-chemical platform for the production of a wide range of added-value compounds for pharmaceutical, cosmetic and food ingredients. This molecule was also evaluated as an alternative solvent for the extraction of several bioactive compounds compared to n-hexane. Limonene was extracted from the essential oils of orange peels through a solvent-free microwave extraction technique. Limonene was successfully transformed into products with industrial interest by catalytic oxidation using three different iron catalysts. The ability of limonene to be used as an alternative solvent was performed using two simulation tools, Hansen solubility parameters (HSPs) and the Conductor-like Screening Model for Real Solvents (COSMO-RS), and via experimentation. The results indicated that limonene could be a promising green solvent and synthon for petroleum substitution in the extraction or synthesis of bioactive compounds.L'objectif de cette étude est de montrer les potentialités du limonène comme une plateforme agrochimique pour la production d'une large gamme de composés à valeur ajoutée pour les industries pharmaceutique, cosmétique et agroalimentaire. Cette molécule a été évaluée en tant que synthon pour la synthèse de molécules bioactives et comme solvant alternatif à l'hexane pour l'extraction de composés bioactifs. Deux outils de simulation solvant--soluté ont été utilisés pour simuler et optimiser les potentialités du limonène : les paramètres de solubilité Hansen (HSP) et le modèle « Conductor-like Screening Model for Real Solvents » (COSMO-RS). Les résultats indiquent que le limonène peut être un solvant vert et un synthon prometteur pour la substitution du pétrole dans l'extraction ou la synthèse de composés bioactifs.This work was supported in part thanks to funding from the fellowship given to Edinson Yara Varón (No. TECSPR14-2-0029) from the People Programme (Marie Curie Actions) of the Seventh Framework Programme of the European Union (FP7/2007-2013) under REA grant agreement no. 600388 (TECNIOspring programme), and from the Agency for Business Competitiveness of the Government of Catalonia, ACCIÓ

    High Yields of Shrimp Oil Rich in Omega-3 and Natural Astaxanthin from Shrimp Waste

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    A valued marine oil rich in omega-3 lipids and natural astaxanthin is obtained with remarkably high yield (up to 5 wt %) extending to pink shrimp waste (head and carapace) using the approach to extract fish oil from fish processing byproducts using d-limonene. Biobased limonene is an excellent solvent for both unsaturated lipids and astaxanthin-based carotenoids preventing oxidative degradation during the extraction cycle including solvent separation at 85 °C. Explaining the deep red color of the shrimp oil obtained, computational simulation suggests that d-limonene is also a good solvent for natural astaxanthin abundant in shrimp

    CP violation in J/ψΛΛˉJ/\psi \rightarrow \Lambda \bar \Lambda

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    We study CP violation in J/ψΛΛˉJ/\psi \rightarrow \Lambda \bar{\Lambda} decay. This decay provides a good place to look for CP violation. Some observables are very sensitive to the Λ\Lambda electric dipole moment dΛd_\Lambda and therefore can be used to improve the experimental upper bound on dΛd_\Lambda. CP violations in the lepton pair decays of J/ψJ/\psi and Υ\Upsilon are also discussed.Comment: 8 pages, RevTex, UM-P-92/113, OZ-92/3

    Phototransformation of three herbicides: chlorbufam, isoproturon and chlorotoluron: influence of irradiation on toxicity

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    Abstract. The direct phototransformations in aqueous solution of chlorbufam (I), chlorotoluron (II), and isoproturon (III) are compared. III With I and II photohydrolysis (substitution of chlorine atom with formation of the corresponding hydroxylated derivative) is initially almost quantitative. It does not depend on irradiation wavelength in the range 250-300 nm. In contrast with III the main reaction is a free radical rearrangement, the reaction being more efficient at 254 nm than at wavelengths longer than 270 nm. Compounds II and III were also irradiated on sand in the absence of water. Several photoproducts were identified, they result from elimination or oxidation of methyl groups of urea moiety. The toxicity of photoproducts was determined using the standard Microtox test (toxicity on the bacterium Vibrio fischeri). Photohydrolysis of I and II does not change much the toxicity of solutions whereas the oxidation, or at a lower scale the elimination of methyl group on the urea moiety, dramatically increases the toxicity

    A formal verification framework and associated tools for enterprise modeling : application to UEML

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    The aim of this paper is to propose and apply a verification and validation approach to Enterprise Modeling that enables the user to improve the relevance and correctness, the suitability and coherence of a model by using properties specification and formal proof of properties

    Vegetable oils as alternative solvents for green oleo-extraction, purification and formulation of food and natural products

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    Since solvents of petroleum origin are now strictly regulated worldwide, there is a growing demand for using greener, bio-based and renewable solvents for extraction, purification and formulation of natural and food products. The ideal alternative solvents are non-volatile organic compounds (VOCs) that have high dissolving power and flash point, together with low toxicity and less environmental impact. They should be obtained from renewable resources at a reasonable price and be easy to recycle. Based on the principles of Green Chemistry and Green Engineering, vegetable oils could become an ideal alternative solvent to extract compounds for purification, enrichment, or even pollution remediation. This review presents an overview of vegetable oils as solvents enriched with various bioactive compounds from natural resources, as well as the relationship between dissolving power of non-polar and polar bioactive components with the function of fatty acids and/or lipid classes in vegetable oils, and other minor components. A focus on simulation of solvent-solute interactions and a discussion of polar paradox theory propose a mechanism explaining the phenomena of dissolving polar and non-polar bioactive components in vegetable oils as green solvents with variable polarity.Edinson Yara Varón thanks to fellowship funding (No. TECSPR14-2-0029) from the People Programme (Marie Curie Actions) of the Seventh Framework Programme of the European Union (FP7/2007-2013) under REA grant agreement No. 600388 (TECNIOspring programme), and from the Agency for Business Competitiveness of the Government of Catalonia, ACCIÓ. Ying Li would like to thank the National Natural Science Foundation of China (Grant 31701633) and the Fundamental Research Funds for the Central Universities (Grant 17817028), as well as special funds from “SanWu Talent 2014” and sixth “100-Talent” Programs

    Review: Towards the agroecological management of ruminants, pigs and poultry through the development of sustainable breeding programmes. II. Breeding strategies

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    Agroecology uses ecological processes and local resources rather than chemical inputs to develop productive and resilient livestock and crop production systems. In this context, breeding innovations are necessary to obtain animals that are both productive and adapted to a broad range of local contexts and diversity of systems. Breeding strategies to promote agroecological systems are similar for different animal species. However, current practices differ regarding the breeding of ruminants, pigs and poultry. Ruminant breeding is still an open system where farmers continue to choose their own breeds and strategies. Conversely, pig and poultry breeding is more or less the exclusive domain of international breeding companies which supply farmers with hybrid animals. Innovations in breeding strategies must therefore be adapted to the different species. In developed countries, reorienting current breeding programmes seems to be more effective than developing programmes dedicated to agroecological systems that will struggle to be really effective because of the small size of the populations currently concerned by such systems. Particular attention needs to be paid to determining the respective usefulness of cross-breeding v. straight breeding strategies of well-adapted local breeds. While cross-breeding may offer some immediate benefits in terms of improving certain traits that enable the animals to adapt well to local environmental conditions, it may be difficult to sustain these benefits in the longer term and could also induce an important loss of genetic diversity if the initial pure-bred populations are no longer produced. As well as supporting the value of within-breed diversity, we must preserve between-breed diversity in order to maintain numerous options for adaptation to a variety of production environments and contexts. This may involve specific public policies to maintain and characterize local breeds (in terms of both phenotypes and genotypes), which could be used more effectively if they benefited from the scientific and technical resources currently available for more common breeds. Last but not least, public policies need to enable improved information concerning the genetic resources and breeding tools available for the agroecological management of livestock production systems, and facilitate its assimilation by farmers and farm technicians
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