9742 research outputs found

    Metabolome profiling of cacao ( Theobroma cacao L.) callus under drought stress conditions induced by polyethylene glycol (PEG) as osmoticant

    No full text
    International audienceAbstract Introduction The cacao tree ( Theobroma cacao ), a perennial crop that serves as a source of cacao beans, can suffer from drastic climate changes such as irregular rainfall and shorter rainy seasons. The search for hybrids which are capable of producing specific metabolites favoring adaptation in new climatic conditions is a challenge in cacao farming. Objectives We aimed to (1) analyze the metabolic changes in calli of three cacao genotypes during water deficit induced by incubation with polyethylene glycol and (2) assess their response to water deficit stress with regard to somatic embryo differentiation. Methods Metabolic profiling was carried out using 1 H‐NMR spectroscopy and multivariate data analysis was applied to crude extracts of calli grown in non‐stress or water deficit stress conditions. Results Water deficit stress influences the capacity of calli to produce embryos. The SCA12 genotype exhibited the best conversion capacity under severe conditions and was considered as tolerant to drought, followed by the SCA6 genotype (mid‐tolerant) and the MA12 genotype (sensitive). Fifty‐four metabolites were identified in the three cacao genotypes and discriminant metabolites were identified. Metabolites involved in water stress tolerance such as fructose, trans ‐aconitic acid, leucine, and hydroxybenzene derivatives were observed in SCA12, the tolerant genotype. Conclusion These results demonstrate the utility of 1 H‐NMR metabolomics as an essential tool for the analysis of the drought tolerance characteristics of T. cacao

    Theoretical Foundations of Community Rating by a Private Monopolist Insurer: Framework, Regulation, and Numerical Analysis

    No full text
    Community rating is a policy that mandates uniform premium regardless of the risk factors. In this paper, our focus narrows to the single contract interpretation wherein we establish a theoretical framework for community rating using Stiglitz's (1977) monopoly model in which there is a continuum of agents. We exhibit profitability conditions and show that, under mild regularity conditions, the optimal premium is unique and satisfies the inverse elasticity rule. Our numerical analysis, using realistic parameter values, reveals that under regulation, a 10% increase in indemnity is possible with minimal impact on other variables

    Théâtres de la naissance et poétiques de l’accouchement

    No full text

    Simultaneous charging and discharging processes in latent heat thermal energy storage: A review

    No full text
    International audienceThis review presents a first state-of-the-art for latent heat thermal energy storage (LHTES) operating with a simultaneous charging-discharging process (SCD). These systems combine the thermal behaviour of a storage with a phase change material (PCM) and the behaviour of a heat exchanger with heat transfer between two heat thermal fluids (HTF). A bibliometric analysis is conducted to identify relevant documents and also to highlight the growing interest in scientific research for LHTES with a SCD. Existing studies are analysed according to the geometry of the storage, the heat transfer process to charge and discharge the PCM and the applications. In order to provide a complete review, studies are also categorized according to the method used to enhance heat transfer between the heat exchangers and the PCM. Based on the current state-of-the-art, the advantages of SCD compared to conventional LHTES with independent charging and discharging (ICD) are discussed in term of thermal performance and efficiency. To conclude, guidelines, recommendations and perspectives are suggested for future research to select the appropriate PCM, assess the thermal performance, design the storage and enhance heat transfer

    O-acylation régiosélective biocatalytique des lactones sesquiterpéniques de la chicorée : une voie vers de nouveaux dérivés esters

    No full text
    International audienceWe report the first biocatalytic modification of sesquiterpene lactones (STLs) found in the chicory plants, specifically lactucin (Lc), 11β,13dihydrolactucin (DHLc), lactucopicrin (Lp), and 11β,13-dihydrolactucopicrin (DHLp). The selective O-acylation of their primary alcohol group was carried out by the lipase B from Candida antarctica (CAL-B) using various aliphatic vinyl esters as acyl donors. Perillyl alcohol, a simpler monoterpenoid, served as a model to set up the desired O-acetylation reaction by comparing the use of acetic acid and vinyl acetate as acyl donors. Similar conditions were then applied to DHLc, where five novel ester chains were selectively introduced onto the primary alcohol group, with conversions going from >99 % (acetate and propionate) to 69 % (octanoate). The synthesis of the corresponding O-acetyl esters of Lc, Lp, and DHLp was also successfully achieved with near-quantitative conversion. Molecular docking simulations were then performed to elucidate the preferred enzyme-substrate binding modes in the acylation reactions with STLs, as well as to understand their interactions with crucial amino acid residues at the active site. Our methodology enables the selective O-acylation of the primary alcohol group in four different STLs, offering possibilities for synthesizing novel derivatives with significant potential applications in pharmaceuticals or as biocontrol agents.Nous rapportons la première modification biocatalytique de lactones sesquiterpéniques (STL) présentes dans la chicorée, à savoir la lactucine (Lc), la 11β,13dihydrolactucine (DHLc), la lactucopicrine (Lp) et la 11β,13-dihydrolactopicrine (DHLp). La lipase B de Candida antarctica (CAL-B) a procédé à la O-acylation sélective de leur groupe alcool primaire en utilisant divers esters vinyliques aliphatiques comme donneurs d'acyle. L'alcool périllylique, un monoterpénoïde plus simple, a servi de modèle pour mettre en place la réaction d'O-acétylation souhaitée en comparant l'utilisation de l'acide acétique et de l'acétate de vinyle comme donneurs d'acyle. Des conditions similaires ont ensuite été appliquées au DHLc, où cinq nouvelles chaînes ester ont été sélectivement introduites sur le groupe alcool primaire, avec des conversions allant de >99 % (acétate et propionate) à 69 % (octanoate). La synthèse des esters O-acétyliques correspondants de Lc, Lp et DHLp a également été réalisée avec succès, avec une conversion quasi quantitative. Des simulations de docking moléculaire ont ensuite été réalisées pour élucider les modes de liaison enzyme-substrat préférés dans les réactions d'acylation avec les STL, ainsi que pour comprendre leurs interactions avec les résidus d'acides aminés cruciaux dans le site actif. Notre méthodologie permet l'acylation O sélective du groupe alcool primaire dans quatre STL différentes, offrant des possibilités de synthèse de nouveaux dérivés avec des applications potentielles significatives dans les produits pharmaceutiques ou comme agents de biocontrôle

    Growth-inhibiting effects of the unconventional plant APYRASE 7 of Arabidopsis thaliana influences the LRX/RALF/FER growth regulatory module

    No full text
    International audiencePlant cell growth involves coordination of numerous processes and signaling cascades among the different cellular compartments to concomitantly enlarge the protoplast and the surrounding cell wall. The cell wall integrity-sensing process involves the extracellular LRX (LRR-Extensin) proteins that bind RALF (Rapid ALkalinization Factor) peptide hormones and, in vegetative tissues, interact with the transmembrane receptor kinase FERONIA (FER). This LRX/RALF/FER signaling module influences cell wall composition and regulates cell growth. The numerous proteins involved in or influenced by this module are beginning to be characterized. In a genetic screen, mutations in Apyrase 7 ( APY7 ) were identified to suppress growth defects observed in lrx1 and fer mutants. APY7 encodes a Golgi-localized NTP-diphosphohydrolase, but opposed to other apyrases of Arabidopsis, APY7 revealed to be a negative regulator of cell growth. APY7 modulates the growth-inhibiting effect of RALF1, influences the cell wall architecture and -composition, and alters the pH of the extracellular matrix, all of which affect cell growth. Together, this study reveals a function of APY7 in cell wall formation and cell growth that is connected to growth processes influenced by the LRX/RALF/FER signaling module

    Plastic Additive Manufacturing Versus Circular Economy

    No full text

    Is energy aid allocated fairly? A global energy vulnerability perspective

    No full text
    The escalating climate change crisis is causing many developing countries to become more vulnerable to energy-related challenges, highlighting the issue of fairness in allocating energy aid. Given this context, it is important to ensure countries that face higher energy vulnerabilities receive a greater share of energy aid funding. This study aims to assess the impact of energy vulnerability on energy aid allocation using a double-hurdle model and a panel of 124 countries from 2002 to 2019. We rely on an index of energy vulnerability to understand the differences in the amount of aid available to different energy-vulnerable recipients, and study the transmission mechanisms underlying this relationship. Our results suggest that the allocation of energy aid has been largely fair. Specifically, energy-vulnerable countries are more likely to be selected as recipients of energy aid during the selection stage, and subsequently receive a greater share of this aid during the allocation stage. However, this effect is heterogeneous and asymmetric. Donors tend to allocate energy aid to countries characterized by relatively low quality of government, low income levels, and limited access to energy assistance. Furthermore, disparities exist in the impact of energy vulnerability on different types of energy support. Specifically, countries with higher energy vulnerability receive a greater proportion of energy policy and energy distribution aid, but are allocated a relatively small share of aid to their non-renewable energy-generation sectors. Additionally, the relationship between energy vulnerability and renewable energy generation aid is not statistically significant. Our results highlight the importance of considering energy vulnerability when allocating energy assistance, and have both scholarly and practical significance. Our findings also have important policy implications for donors by providing guidance on how to promote a fairer allocation of energy aid

    k-carrageenan nanocomposite as an efficient acidic bio-based catalyst for the synthesis of 5-hydroxymethylfurfural from fructose

    No full text
    International audienceA novel bio-based nanocomposite was designed based on a modification of halloysite with k-carrageenan via precipitation polymerization with acrylic acid in aqueous media. Various techniques such as X-ray diffraction (XRD), infrared spectroscopy (FT-IR), thermo gravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) were conducted to verify the formation of the catalyst. Afterward, it was tested as a solid acid catalyst for the dehydration of fructose, resulting in the production of 5-hydroxymethylfurfural (HMF). Effective parameters, such as catalyst amount, temperature, and reaction time were optimized and it was revealed that 10 wt% catalysts at 100 °C gave the desired product (HMF, 97.9 % yield) in 35 min. The catalyst was also reusable and could be reused for up to four runs. k-carrageenan as a carbohydrate-containing acidic functionality in the backbone of prepared nanocomposite was successfully applied for improving the catalytic activity of halloysite. Thus, the present protocol can open up an innovative opportunity for the preparation of a bio-based catalytic system from naturally occurring components for the conversion of fructose to 5-hydroxymethylfurfural

    583

    full texts

    21,674

    metadata records
    Updated in last 30 days.
    HAL-Artois is based in France
    Access Repository Dashboard
    Do you manage Open Research Online? Become a CORE Member to access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard! 👇