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Hybridization assessment model allowing the evaluation and comparison of hybrid solar systems
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Impact of Liquid Structure on Thermodynamics and Kinetics of Chemical Reactions: Experimental and Molecular Simulations Demonstration with Acid Gas Absorption
No full textInternational audienceThe chemical absorption of CO2 and H2S in aqueous tertiary amines are well-known acid-base reactions. Important applications are the purification of fuel gases like natural gas, syngas and biogas, and the removal of carbon dioxide from flue gas.Here we present new kinetic and vapor-liquid equilibrium experiments that show that the addition of an amide such as HMPA, that is known to be a strong liquid structure maker, significantly inhibits the acid-base reactions. The impact is more pronounced for CO2 than for H2S absorption. Despite the presence of a large excess of water in the solvent, the absorption becomes almost physical. Due to hydrogen bonding and the hydrophobic effect, each amide molecule is involved in a cluster containing several water molecules thus rendering the water molecules less available to participate in the reaction and to solvate HS- and HCO3- ions.This effect is absent when ethylene glycol, a weak structure maker, is added, even in large quantities.Subsequently, we investigated whether state-of-the-art molecular dynamics simulations could capture this effect. However, simulations of the water-HMPA system could not even reproduce the strongly negative excess volume of the mixture. This illustrates the need for more accurate force fields to simulate the structuring effect and their impact on chemical reactions.This study clearly demonstrates the importance of solvent structure in the study of chemical reactions
Modified Co/TiO2 catalysts for CO2 hydrogenation to fuels
No full textInternational audienceThe direct CO2 conversion to liquid fuels by catalytic hydrogenation (CO2-based Fischer-Tropsch synthesis, FTS), is a sustainable approach to reduce CO2 emissions. This challenging reaction proceeds through tandem catalysis involving reverse water gas shift reaction to produce CO and subsequent traditional CO-FTS. Unmodified Co-based catalysts allow performing the reaction at low temperatures (< 250 °C), albeit producing mainly methane. In this study, we modified a commercial TiO2-P25 support by NaBH4 reduction so as to introduce controlled amounts of promoters and oxygen vacancies (Ov). The modified and unmodified supports were used to prepare Co-based catalysts, which were evaluated for CO2-based FTS at 220-250 °C and 20 bar. The promoted catalysts outperform the one prepared on commercial TiO2 in terms of activity and selectivity towards C5+. Detailed characterizations of the catalysts were performed to decipher the role of promoters. We show that, besides improving CO2 activation and limiting H2 activation, the presence of alkali on the support allows a modulation of hydrogen spillover in the system. The best catalyst in terms of activity and selectivity is the one for which sodium is deposited in sufficient amount to modulate the hydrogen spillover, which allows an optimal surface C/H ratio on cobalt
The effect of low back pain on spine kinematics: A systematic review and meta-analysis: Review
No full textInternational audienceBackgroundAlthough impairments in dorso-lumbar spine mobility have been previously reported in patients with low back pain, its exact mechanism is not yet clear. Therefore, the purpose of this systematic review and meta-analysis is to investigate and compare spinal kinematics between subjects with and without low back pain and identify appropriate tools to evaluate it.MethodsThe PubMed, Scopus and Web of Science databases were searched for relevant literature. The search strategy was mainly focused on studies investigating lumbar kinematics in subjects with and without low back pain during clinical functional tests, gait, sports and daily functional activities. Papers were selected if at least one of these outputs was reported: lumbar range of motion, lumbar velocity, lumbar acceleration and deceleration, lordosis angle or lumbar excursion.FindingsAmong 804 papers, 48 met the review eligibility criteria and 29 were eligible to perform a meta-analysis. Lumbar range of motion was the primary outcome measured. A statistically significant limitation of the lumbar mobility was found in low back pain group in all planes, and in the frontal and transverse planes for thoracic range of motion, but there is no significant limitation for pelvic mobility. The amount of limitation was found to be more important in the lumbar sagittal plane and during challenging functional activities in comparison with simple activities.InterpretationThe findings of this review provide insight into the impact of low back pain on spinal kinematics during specific movements, contributing to our understanding of this relationship and suggesting potential clinical implications
A systematic approach to classify and characterize genomic islands driven by conjugative mobility using protein signatures
No full textInternational audienceGenomic islands (GIs) play a crucial role in the spread of antibiotic resistance, virulence factors and antiviral defense systems in a broad range of bacterial species. However, the characterization and classification of GIs are challenging due to their relatively small size and considerable genetic diversity. Predicting their intercellular mobility is of utmost importance in the context of the emerging crisis of multidrug resistance. Here, we propose a large-scale classification method to categorize GIs according to their mobility profile and, subsequently, analyze their gene cargo. We based our classification decision scheme on a collection of mobility protein motif definitions available in publicly accessible databases. Our results show that the size distribution of GI classes correlates with their respective structure and complexity. Self-transmissible GIs are usually the largest, except in Bacillota and Actinomycetota, accumulate antibiotic and phage resistance genes, and favour the use of a tyrosine recombinase to insert into a host's replicon. Non-mobilizable GIs tend to use a DDE transposase instead. Finally, although tRNA genes are more frequently targeted as insertion sites by GIs encoding a tyrosine recombinase, most GIs insert in a protein-encoding gene. This study is a stepping stone toward a better characterization of mobile GIs in bacterial genomes and their mechanism of mobility
Oxygen content effect on mechanical behaviour of cp titanium exposed at elevated temperature.
No full textInternational audienceTi-based alloys are particularly prone to oxygen dissolution and embrittlement. Oxygen solubility within titanium leads to the formation of an oxygen-diffusion zone (ODZ) during oxidation processes for a depth up to ten times thicker than the oxide layer. The mechanical and oxidation behaviour of the CP-Ti was investigated using micro-tensile testing of 50 to 800 μm-thick pre-oxidized specimens. Pre-oxidation treatments at 700 °C with various exposures have been performed to generate different ODZ thickness/non-affected material (NAM) thickness ratios ranging from 0 to 100%. These investigations aimed to identify the competition between strengthening effects due to oxygen enrichment and the damage development due to oxygen embrittlement using the graded-property material structure composed of different percentages of NAM and ODZ. Mechanical properties of CP-Ti rise with oxidation time except for strain to failure. The extension of the ODZ follow parabolic law with a parabolic constant 20 μm².h-1
Monte-carlo and sensitivity transport model: application in solar energy
No full textInternational audienceThe classical transport model of radiative transfer uses the specific intensity as the descriptor. By differentiating the transport model of intensity with respect to a geometric parameter, a model of geometric sensitivity can be built. In this work, a classical model of intensity and models ofgeometric sensitivity are built with specular flat mirrors as the boundary conditions and are applied in a concentrated solar power plant. The sensitivities of the impacting power on the receiver with respect to the geometric parameters of each mirror are estimated by the Monte Carlo Method (MCM).Furthermore, by analyzing the sources in the models of geometric sensitivity, the contributions of the typical optical effects: spillage, blocking, and shadowing, to the sensitivity can also be estimated and analyzed, which is essential information to optimize the system
Vers un système de recommandation personnalisé de services métiers dédiés à la prévention de fragilité chez les aînés
No full textInternational audienceFrailty is a clinical syndrome associated with ageing that characterizes an intermediate state between robust health and loss of autonomy. To preserve the abilities of older adults and prevent dependency, it is important to identify and evaluate their frailty. This approach is part of a dependency prevention strategy, based on a thorough understanding of their medical, social, and living environment. This understanding is usually acquired through a significant amount of data collection using standardized evaluation surveys. The obtained data is then analyzed to provide personalized recommendations for the beneficiaries’ lifestyles. Our article presents the concept of frailty and a personalized recommendation system aimed at helping citizens prevent frailty. This system uses an innovative self-assessment approach designed for older adults, without necessarily involving healthcare professionals.La fragilité est un syndrome clinique lié au vieillissement qui caractérise un état intermédiaire entre la santé robuste et la perte d’autonomie. Pour préserver les capacités de la personne âgée et éviter la dépendance, il est important de repérer et d’évaluer sa fragilité. Cette démarche s’inscrit dans une approche de prévention de la dépendance, qui repose sur une compréhension approfondie de sa situation médicale, sociale et de son environnement de vie. Cette compréhension est généralement acquise grâce à une collecte importante de données à l’aide d’enquêtes d’évaluation standardisées. Les données obtenues sont ensuite analysées afin de fournir des recommandations personnalisées aux modes de vie des bénéficiaires. Notre article expose le concept de fragilité ainsi qu’un système de recommandation personnalisé qui a pour objectif d’aider les citoyens à prévenir la fragilité. Ce systèmeutilise une approche novatrice d’auto-évaluation destinée aux personnes âgées, sans que cela n’implique systématiquement le recours à des professionnels de la santé
Frittage sélectif par laser (SLS) : Compréhension des interactions rayonnement-matière par des caractérisations thermo-optiques du polyamide 12 chargé
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Decision Support Systems XIII. Decision Support Systems in An Uncertain World: The Contribution of Digital Twins: 9th International Conference on Decision Support System Technology, ICDSST 2023, Albi, France, May 30 – June 1, 2023, Proceedings
No full textInternational audienceThis book constitutes the proceedings of the 9th International Conference on Decision Support Systems Technologies, ICDSST 2023, held during May 30 – June 1, 2023. The EWG-DSS series of International Conference on Decision Support System Technology (ICDSST) is planned to consolidate the tradition of annual events organized by the EWG-DSS in offering a platform for European and international DSS communities, comprising the academic and industrial sectors, to present state-of-the-art DSS research and developments, to discuss current challenges that surround decision-making processes, to exchange ideas about realistic and innovative solutions, and to co-develop potential business opportunities. The main theme of this year was “Decision Support Systems in An Uncertain World: The Contribution of Digital Twins”. The 21 papers presented in this volume were carefully reviewed and selected from 65 submissions. They were organized in topical sections as follows: DSS models, methods, and tools; DSS for business performance and stakeholders; DSS applications for sustainability in health, energy and transportation; and DSS users and successful adoption