Portail HAL de l'Université du Littoral Côte d'Opale
Not a member yet
11255 research outputs found
Sort by
Investing in nature: Stakeholder’s willingness to pay for Tunisian forest services
No full textInternational audienceThis study explores the economic value of Aleppo pine forests, a unique and threatened ecosystem in the border region of central Tunisia. These forests play a vital role in supporting small rural communities, but face increasing pressures and restrictions on their use. This research aims to assign a monetary value to forest conservation, considering the region’s specific socio-economic context. Strategies for empowering local residents as key actors in developing sustainable cross-border initiatives are further investigated. Employing the Contingent Valuation Method, a survey of 350 local residents and international users was conducted to assess their Willingness to Pay for forest conservation efforts. Logistic regression analysis revealed that sociodemographic factors, such as monthly income and preferred payment method, significantly influence both and the likelihood of participation. These findings highlight the feasibility and importance of reconciling economic development with ecological sustainability in this critical region
Jet-cooled and long path cell high resolution infrared spectroscopy of furfural conformers from fourier transform and GCL measurements
No full textInternational audienceFurfural, C₄H₃OCHO, is a volatile organic compound produced from biomass burning. Its oxidation may lead to secondary organic aerosol formation, making it necessary to provide accurate spectroscopic data to evaluate its impact. Two conformations exist in the gas phase, with the oxygen atoms oriented in a more stable trans configuration than the cis one. Durig et al.ᵃ exploited far-infrared (IR) data to determine relative stabilities and the conformational barrier height. Motiyenko et al.ᵇ conducted extensive microwave spectroscopic studies providing molecular parameters in the ground state (GS) and low-lying vibrational states up to 400 cm−¹. No splitting due to the internal rotation of the CHO top has been observed in these states. We report here a high-resolution study of furfural across a wide infrared range, combining the Jet-AILES setup, a continuous supersonic jet on the IR AILES beamline at SOLEIL, and a long path cell, both coupled to a Fourier Transform Spectrometer and the SPIRALES setup at MONARIS, a pulsed supersonic jet coupled to mid-IR quantum cascade lasersᶜ. In the fingerprint region, 7 bands of trans- and 2 bands of cis-furfural were recorded at low temperature. About 15,000 lines from GS and 7(2) excited states (ES) of trans(cis-)furfural, respectively, were fitted within experimental accuracy. In the far-IR range, global fits including GS and ES rotational and ES rovibrational transitions enable the refinement of molecular parameters derived from the microwave study and the determination of precise vibrational band centers
Voluntary exercise in mice triggers an anti-osteogenic and pro-tenogenic response in the ankle joint without affecting long bones
No full textInternational audienceBiomechanical stimulation is proposed to occupy a central place in joint homeostasis, but the precise contribution of exercise remains elusive. We aimed to characterize in vivo the impact of mechanical stimulation on the cell-controlled regulation of ossification within the ankles of healthy mice undergoing mild physical activity. DBA/1 male mice were subjected to voluntary running exercise for two weeks, and compared to mice housed in standard conditions (n = 20 per group). Free access to activity wheels resulted in a running exercise of 5.5 ± 0.8 km/day at 14.5 ± 0.5 m/min. Serum levels of alkaline phosphatase, IL-6, IL-8/Kc, IL-17a, and TNF-α were measured. No change in systemic inflammation was detected. The bone architecture of the femur and the calcaneus was unchanged, as revealed by μCT and histology of the enthesis of the Achilles tendon. mRNAs were extracted from femurs, tibias, and ankle joints before RT-qPCR analysis. The expression of the mechanosensitive genes Sclerostin (Sost) and Periostin (Postn) was not impacted by the exercise in long bones. Oppositely, Sost and Postn levels were modulated by exercise in joints, and osteogenic markers (Col10a1, Runx2, Osx, and Dmp1) were downregulated in the exercise group. In addition, the tenogenic markers Scx, Mkx, and Tnmd were upregulated by exercise. Thus, voluntary exercise affected the phenotype of joint cells without impacting long bones. As gene expression of Bmp2, Bmp4, and Id1 was also reduced in these cells, an off-regulation of BMP signaling could be partly responsible for their mechanosensitive response. Running exercise seemed to preserve the tendon from its progressive ossification, as seen in numerous enthesopathies. This study paves the way to future experiments for investigating the effects of mechanical stimulation in various mouse models
Optimisation de la filière plantes aromatiques/huiles essentielles dans un contexte de phytomanagement : impact sur le microbiote des sols pollués par les éléments traces
No full textPhytomanagement corresponds to the integrated management of polluted sites and soils, based on the in situ installation of a plant cover aimed at: reducing the risk of toxicity of polluted soils by immobilizing trace elements (TE) in the rhizosphere (phytostabilization), enabling the ecological rehabilitation of polluted soils by increasing biodiversity and soil microbial activity and, restoring a socio-economic benefit to polluted sites by valorizing biomass, via the development of eco-responsible channels. In this context, the cultivation of aromatic and medicinal plants (MAP) for the production of essential oils (EO) was recently presented as an innovative and economically viable alternative for the phytomanagement of polluted soils, as part of the DEPHYTOP project funded by ADEME. My contribution to this project has enabled me to assess the relevance of this management method, based on the in situ cultivation of MAP, angelica and coriander, and the use of mineral amendments (steel slags) or biological amendment (mycorrhizal inoculum) for the phytomanagement of TE-polluted soil. Various parameters were studied: plant growth, biomass production, HE content and quality, microbial biomass (fatty acids associated with phospholipids), microbial community composition and structure (metagenomic analysis - MiseqIllumina) and soil metabolic potential (Biolog ecoplate). Both coriander and angelica grew well on the soil polluted by the TE, and produced a significant amount of biomass. Nevertheless, the amendments did not significantly increase plant biomass, yield or quality of angelica EO. On the other hand, the quality of angelica EO is very satisfactory, with low levels of TE or pesticide residues (traces). Its chemical composition is not modified by the presence of TE in the soil, nor by mycorrhizal inoculation, and is identical to that of a commercial EO. Biological properties that can be used in non-food applications, such as crop protection (fungistatic and herbicidal effects) and human health (anti-inflammatory and antioxidant effects), have been demonstrated. The technical and economic analysis of the MAP-EO sector highlights the high economic potential of angelica in the phytomanagement of soil polluted by the TE. The cultivation of MAP and its duration influenced the bacterial and fungal communities of the polluted soil, leading to an increase in total microbial biomass, overall metabolic activity and C metabolism. In addition, mycorrhizal inoculation significantly improved bacterial diversity and biomass after three years of cultivation, and increased positive interactions between microorganisms in the soil polluted by the TE. Finally, these results, combined with the study of the social acceptability of EO from polluted soils, demonstrate the potential of the MAP-EO sector in a phytomanagement strategy for soil polluted by the TE.Le phytomanagement correspond à une gestion intégrée des sites et sols pollués, reposant sur la mise en place in situ d’un couvert végétal visant à : réduire le risque de toxicité des sols pollués en immobilisant les éléments traces (ET) dans la rhizosphère (phytostabilisation), permettre la réhabilitation écologique des sols pollués en augmentant la biodiversité et l’activité microbienne du sol et, redonner un bénéfice socio-économique aux sites pollués en valorisant la biomasse, via le développement de filières éco-responsables. Dans ce contexte, la culture de plantes aromatiques et médicinales (PAM), destinée à la production d'huiles essentielles (HE) a été récemment présentée dans le cadre du projet DEPHYTOP, financé par l’ADEME, comme une alternative innovante et économiquement viable pour le phytomanagement des sols pollués. Ainsi, ma contribution dans ce projet a permis d‘évaluer la pertinence de ce mode de gestion reposant sur la culture in situ de PAM, l'angélique et la coriandre et l’emploi d’amendements minéraux (laitiers sidérurgiques) ou biologiques (inoculum mycorhizien) pour le phyto-management de sols pollués par des ET. À ce titre, différents paramètres ont été suivis : la croissance des plantes, la production de biomasse, la teneur et la qualité des HE ainsi que la biomasse microbienne (acides gras associés aux phospholipides), la composition et la structure des communautés microbiennes (analyse métagénomique - MiseqIllumina) et le potentiel métabolique (Biolog ecoplate) du sol. La coriandre ainsi que l’angélique se sont correctement développées sur le sol pollué, et ont produit une quantité importante de biomasse. Néanmoins, les amendements n'ont pas significativement augmenté la biomasse de la plante, ni les rendements ou la qualité de l’HE d’angélique. En revanche, l’HE d’angélique présente une qualité très satisfaisante, caractérisée par une faible teneur en ET ou en résidus de pesticides (traces). Sa composition chimique, n’est pas modifiée par la présence d’ET dans le sol, ni par l’inoculation mycorhizienne, et est identique à celle d’une HE commerciale. Des propriétés biologiques valorisables dans des filières non-alimentaires, tels que la protection des cultures (effets fongistatiques, et herbicides) ou la santé humaine (effets anti-inflammatoires et antioxydants) ont été mises en évidence. L’analyse technico-économique de la filière PPAM-HE souligne le haut potentiel économique de l’angélique dans une démarche de phytomanagement de sols pollués par les ET. La culture de PPAM et sa durée ont influencé les communautés bactériennes et fongiques du sol pollué, entraînant une augmentation de la biomasse microbienne totale, de l’activité métabolique globale, et du métabolisme du C. En outre, l'inoculation mycorhizienne a amélioré de manière significative la diversité et la biomasse bactérienne après trois années de culture et a permis d’augmenter les interactions positives entre les microorganismes du sol pollué. Enfin, ces résultats combinés à l’étude d’acceptabilité sociale des HE issues de sols pollués, montrent le potentiel de la filière PPAM-HE dans une stratégie de phytomanagement d’un sol pollué par les ET
Estimation of Ionic Impurities in Poly(propylene Glycol) Diacrylate Monomers/Liquid Crystal E7 Mixtures Using Dielectric Spectroscopy
No full textInternational audienceThe study investigated the effect of the molecular weight of three difunctional poly(propylene glycol) diacrylates on the temperature-dependent ionic conductivity of these monomers and their blends with an eutectic nematic liquid crystal mixture (E7). The results revealed two distinct regions. At low temperatures, ionic conduction can be described by the Vogel–Tamman–Fulcher (VTF) equation, while at high temperatures, the conductivity data follow the prediction of the Arrhenius model. The Arrhenius and VTF parameters and their corresponding activation energies were determined using the least squares method. In addition, a conductivity analysis based on an ionic hopping model is proposed. Estimates of ion concentrations and diffusion constants were calculated. It was found that both the ionic concentration and the diffusion constant decrease with the increase in the molecular weight of the monomers. The static dielectric permittivity decreases in the following order: TPGDA, PPGDA540, and PPGDA900. This can be explained by the higher dipole moment of TPGDA, which is caused by an enhanced volume density of carbonyl groups.L'étude a porté sur l'effet du poids moléculaire de trois poly(propylène glycol) diacrylates difonctionnels sur la conductivité ionique en fonction de la température de ces monomères et de leurs mélanges avec un mélange de cristaux liquides nématiques eutectiques (E7). Les résultats ont révélé deux régions distinctes. À basse température, la conduction ionique peut être décrite par l'équation de Vogel-Tamman-Fulcher (VTF), tandis qu'à haute température, les données de conductivité suivent la prédiction du modèle d'Arrhenius. Les paramètres d'Arrhenius et de VTF ainsi que les énergies d'activation correspondantes ont été déterminés à l'aide de la méthode des moindres carrés. En outre, une analyse de la conductivité basée sur un modèle de saut ionique est proposée. Des estimations des concentrations d'ions et des constantes de diffusion ont été calculées. Il a été constaté que la concentration ionique et la constante de diffusion diminuent avec l'augmentation du poids moléculaire des monomères. La permittivité diélectrique statique diminue dans l'ordre suivant : TPGDA, PPGDA540 et PPGDA900. Cela peut s'expliquer par le moment dipolaire plus élevé du TPGDA, qui est dû à une densité volumique accrue des groupes carbonyles
Restituer un bâti disparu: Les maisons du pont Notre-Dame vers 1720
No full textNational audienceCette communication a pour objectif d’illustrer une collaboration interdisciplinaire entre SHS (Histoire, Histoire de l'Art) et sciences informatiques, au travers de les restitution des maisons du Pont Notre-Dame à Parsi, en 1720. Elle montre les complémentarités nécessaires aux travaux de restitutions et les apports que la synthèse d'images peut fournir aux sciences historiques
SOMLIT (Service d'Observation en Milieu Littoral) time series (French Research Infrastructure ILICO): long-term core parameter monitoring of French coasts
No full textSOMLIT (Service d'Observation en Milieur Littoral) : a French Coastal Monitoring Network Coastal zones are where land, ocean and atmosphere interact. They are important for the exchange of matter and energy, and play a key role in (biogeo)chemical cycles at global scale. These environments are characterised by significant spatial and temporal variability of their physico-chemical and biological parameters due to local and seasonal meteorological drivers which are exacerbated by large-scale climate drivers (e.g. global warming, modification of the wind regime) and local-scale anthropogenic drivers (e.g. nutrient cycle changes linked to the use of fertilisers or the construction of large installations such as dams). These driving mechanisms are often interconnected. In the context of global warming (due to climate and human-induced changes), the identification and understanding of their impact on coastal marine and littoral ecosystems is essential. The scientific objective of SOMLIT is to 1) characterise the multi-decadal evolution of coastal marine and littoral ecosystems, and 2) determine the climatic and anthropogenic drivers. In order to meet this objective, a nationally coordinated multi-site monitoring system was set up in the mid-1990s. The observation strategy is the same for each of the 12 monitored ecosystems with fortnightly sampling and/or measurements, at high tide (for sites subject to tides): 1) in surface-water for a range of 15 parameters (temperature, salinity, dissolved oxygen, pH, nitrate, nitrite, ammonium, phosphate, silicate, suspended particulate matter, chlorophyll a, particulate organic carbon and nitrogen and stable isotopes of particulate organic carbon and nitrogen), 2) in surface-water for a range of 26 parameters of numbering and optical characteristics of pico- and nanoplankton), and 3) along the water column for temperature, salinity, fluorescence and PAR (vertical profiles of multi-parameter probes). SOMLIT’s activities are carried out under a quality assurance / quality control process based on the ISO 17025 standard. SOMLIT’s service provision objectives are to provide data and logistical support for research and other observation activities. SOMLIT has been officially accredited since 1996 as one of the CNRS (French National Centre for Scientific Research) National Observation Services (SNO). SOMLIT’s coordination is hosted by the Observatoire Aquitain des Sciences de l'Univers (University of Bordeaux / CNRS) and the service relies on strong partnerships with nine other institutions (University of Lille, University of the Littoral Opal Coast, University of Caen Normandy, Sorbonne University, University of Western Brittany, La Rochelle University, University of Montpellier, Aix Marseille University, National Museum of Natural History). SOMLIT is one of the nine networks that compose France’s Coastal Research Infrastructure (ILICO). SOMLIT has strong ties with ILICO’s other networks such as the SNOs MOOSE (Mediterranean Ocean Observing System on Environment), PHYTOBS (microphytoplankton monitoring) and COAST-HF (Coastal Ocean Observing System - High Frequency)
Free Induction Decay signals stimulated and detected by photomixing
No full textInternational audienceThis abstract presents a coherent THz spectroscopy experiment consisting in recording the free induction decay of a collection of carbonyde sulfide (OCS) molecules when polarized coherently by a ~0.29 THz incident pulse resonant with the J=24- >23 OCS rotational line. This was accomplished by employing an optical-cavity-enhanced low-temperature-grown GaAs photoconductor, which was pumped by a free running dual-frequency Ti:Sa laser serving as both a THz pulsed emitter and an optoelectronics mixer. The success of this experiment can be attributed to the exceptional performance of our mixer, boasting a record-conversion efficiency of 30 dB, and the sustained long-term spectral purity of 100 kHz provided by the dual-frequency laser, lasting for over 10 seconds
Experimental challenges in differential scanning calorimetry for Hydrogen storage applications
No full textInternational audienceDihydrogen appears to be a promising energy vector. Technological advances in its storage now make it possible to store it in its pure state in liquid, solid or gaseous form, or combined in molecules such as ammonia, methanol or methane. Another means of storage is adsorption in porous structures. However, this process is impacted by the thermal properties of the adsorbent materials, highlighting the importance of exploring thermal parameters in these materials.The heat capacity (Cp) is one of these characteristics, it plays a primordial role in adsorption phenomena, as enhancing the heat capacity of a solid adsorbent helps reducing the adverse thermal effects resulting from the heat of adsorption. Differential scanning calorimeter (DSC) can be used to determine heat capacity. The implementation of this technique on powdery samples with low heat capacity is however delicate when precise quantification of these values is desired at low temperatures, from -180°C to 25°C.As part of this study, the aim is to determine the heat capacity of metal-organic framework (MOF) powders, which are used for dihydrogen storage by adsorption. Few experimental measurements of their heat capacity at low temperatures exist, and results are sometimes inconsistent. The DSC used was the Q1000 from TA Instruments, employing the heat flow method with TzeroTM technology. After Cp measurement tests with the DSC Standard mode, the experiments were carried out in modulated mode. This mode, where a small sinusoidal modulation of a temperature is applied to the linear increase in temperature, provides more precise results than the DSC Standard mode. The analysis includes factors such as crucible positioning, pelletizing pressure, sample diameter, and volume in the crucible, to study their effects on heat capacity values