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Effects of drying processes, pulsed electric fields and pressing on functional properties, color and biochemical composition of Sargassum muticum (Yendo) Fensholt 1955 (Ochrophytina, Fucales)
No full textInternational audienceThis study examines the effects of pretreatments (pulsed electric fields and mechanical pressing with a rubber membrane) and drying processes (freeze-drying, oven drying, and air jets impingement drying) on the physical properties and biochemical composition seaweed Sargassum muticum (Yendo) Fensholt 1955 (Ochrophytina, Fucales). The research analyzes changes in functional properties, color, biochemical composition, and microstructure. Results show that pretreatments and drying methods can significantly impact the biochemical composition and color of dried seaweeds. Freeze-drying preserves neutral sugars, uronic acids and mineral matter better with value of 1.75 ± 0.12 %Fresh Seaweed(FS), 2.06 ± 0.20 %FS and 3.37 ± 0.22 %FS respectively. Oven drying however, has the most significant impact, as is also the case for mineral compounds after the succession of pulsed electric fields and freeze-drying. A reduction of 5.7 % to 9.0 % in mineral content was observed. Concerning the pressing pretreatment, it increases compounds retention in dried seaweeds. The effects on uronic acids content vary depending on the combination of pretreatment and drying method, passing for example, from 2.75 %FS after a 5-min pressing and air jets drying at 21 m s−1 to 3.08 %FS for a 10-min pressing and 7 m s−1 air jets drying. Moreover, microstructure analysis reveals that drying processes, including freeze-drying, alter the seaweed's internal structure. The study highlights the importance of selecting appropriate pretreatment and drying methods based on the desired properties of the final dried seaweed product
Innovative Tool for Improving Surface Quality in Single Point Incremental Forming: A Comparison with Hemispherical Tools
No full textInternational audienceSingle Point Incremental Forming (SPIF) has emerged as a flexible and cost-effective technique for producing complex sheet metal parts. However, its industrial application is often limited by issues related to surface quality. This study examines the impact of tool geometry on the surface integrity of the AA6061-T6 aluminum alloy. The research novelty lies in the innovative eccentric tool with a variable radius (ETVR), which we compare to two conventional hemispherical tools with radii of 5 mm and 10 mm. Truncated cones were formed under the same process conditions, and their quality was assessed by measuring surface roughness and microhardness along the cone’s generatrix in both the rolling direction and the transverse direction. Additionally, microchip analysis and visual inspections were conducted. The results reveal distinct differences in the surface morphology, evolution of roughness, and distribution of microhardness among the three tools. The SS5 tool produced the highest level of hardening but also resulted in significant surface deterioration. In contrast, the SS10 tool generated smoother surfaces with moderate hardening, while the ETVR tool struck a balance between surface uniformity and enhanced hardness. Statistical analyses, using t-tests, confirmed the significance of these findings. This study offers new insights into tool design for SPIF, highlighting the trade-offs between surface quality and material strengthening
Prediction of compatibility and chemical structure influencing plasticization of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB)
No full textInternational audienceThis study aims to predict the plasticization of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB) using two theoretical approaches: polymer-plasticizer compatibility via Hansen solubility parameters, and the chemical structure of polymers through the prediction of the entanglement molecular weight (M e ) based on Van Krevelen's method. Hansen solubility parameters were calculated for three P3HB4HB copolymers with varying 4HB molar contents (10 %, 15 % and 30 %), allowing for the identification of potentially compatible plasticizers. In parallel, M e was theoretically predicted and compared to experimental rheological measurements. The discrepancies observed highlight the significant influence of crystallinity, particularly the size and distribution of spherulites, on the viscoelastic behavior of the materials. The transition to the rubbery plateau, analyzed through oscillatory rheology, confirmed the decisive role of the semi-crystalline structure in governing polymer chain mobility. This dual approach, combining chemical modeling and experimental validation, provides a deeper understanding of the plasticization mechanisms of P3HB4HB. It represents a valuable tool for guiding the formulation of more efficient bio-based materials tailored to industrial requirements
Elastic properties and electronic structure of the lanthanum sulfides MLa2S4 (M = Ca, Sr, Ba)
No full textInternational audienceCaLa2S4 sulfides are promising transparent ceramics for infrared windows application in harsh environment conditions, but the theoretical studies on the mechanical properties of this material are limited. Using density functional theory calculations, we performed a systematic theoretical study on the structural, electronic, bonding, and elastic properties of cubic CaLa2S4. A comparison was made with the cubic SrLa2S4 and BaLa2S4 compounds. The investigations were accomplished by employing the full potential augmented plane wave and the projector augmented wave methods as, respectively, implemented in the WIEN2k and VASP packages. The independent elastic constants and the most important elastic properties (including the bulk modulus B, shear modulus G, Young's modulus E, and Poisson's ratio ν) were determined by precise calculations under normal and different pressures. The degree of elastic anisotropy has been evaluated from 3D curved surface representations of several elastic constants. Experimental values were also performed through ultrasonic velocity and a normal compression testing for CaLa2S4. A comparison with experimental studies was done
Clinical Impact of Treatment Modalities for Zygomatic Fractures on Infraorbital Nerve Sensory Recovery: A Cross-sectional Observational Study
No full textInternational audienceBackground: Lesions of the infraorbital nerve are common sequelae of zygomatic complex fractures, significantly compromising patients' quality of life. This study aimed to identify the most effective treatment method for zygomatic fractures, minimizing sequelae such as persistent numbness, which can significantly affect patients' quality of life. To this end, conservative and surgical approaches and one- and two-point fixation techniques were compared, considering the influence of fracture location on neurosensory and functional prognosis. Materials and Methods: This retrospective, cross-sectional study evaluated the medical records of patients with zygomatic complex fractures. The sample consisted of all medical records of patients from the Federal University of the Jequitinhonha and Mucuri Valleys treated for zygomatic complex fractures between January 2016 and December 2018, evaluating sensory recovery over a 12 months follow-up. Results: 126 medical records were evaluated, with 147 facial fractures, of which zygomatic complex fractures had the highest incidence (31.29%). Most patients were male, with a mean age of 42.5 years. The primary etiology was traffic accidents. In zygomatic complex fractures, the most common signs and symptoms were altered neurosensory function of the infraorbital nerve (78.26%) and infraorbital rim step-off (54.34%). The conservative or non-surgical method was the most used (34.78%), followed by open reduction and internal fixation of the frontozygomatic process and infraorbital rim (32.6%), open reduction and internal fixation of the frontozygomatic process (19.56%), and open reduction and internal fixation of the infraorbital rim (13.04%). Complete resolution of infraorbital nerve sensory disturbances was observed in only 33.33% of patients, of whom 66.7% were treated by open reduction with internal fixation. Conclusions: Thus, open reduction with internal fixation of the infraorbital rim and frontozygomatic process has proven to be a practical approach, promoting better fracture reduction, re-establishment of the orbital contour, and superior aesthetic and functional results, in addition to increasing the chances of neurosensory recovery of the infraorbital nerve
Flow matching pour la super-résolution d'images satellitaires Sentinel-2
No full textInternational audienceFlow matching pour la super-résolution d'images satellitaires Sentinel-
Quantifying coastal cliff retreat, sediment volume, and dynamics using photogrammetry and geospatial analysis in the Pe<acute accent>nestin Peninsula, France
No full textRecently, rocky cliffs globally have garnered immense attention due to their susceptibility to erosion, collapse, and instability, similar to the frequent monitoring of low-lying coastal zones for risks associated with climate change-related sea-level rise and flooding. Historically, sediment volumes have been extensively studied and constrained; however, recent advancements in remote sensing and UAV technology now facilitate more precise quantitative assessments of the volumes of sediment loads involved in these transfers. In this study, we analyse erosion and sediment transport in two sectors of the Penestin Peninsula in South Brittany using high-resolution and high-frequency drone imagery. We integrate an array of geospatial datasets to perform a detailed photogrammetric analysis of approximately 900 m of the Mine d'Or cliff. The resulting topographic and morphological differentials at the land-sea interface reveal significant erosional asymmetry between the southern and northern sectors of the beach, primarily influenced by gravitational forces and urban development at beach access points. Quantitatively, since 1952, the southern sector has experienced a higher average annual retreat compared to the northern slope. Our mapping of the dynamics of coarse and medium sand stocks along the northern coast of the peninsula, spanning the period from 2010 to 2020, indicates that approximately 32,000 m3 of material from cliff erosion has contributed to the sediment accumulation on the shore, particularly within the Branzais Marsh. Furthermore, while 10,000 m3 were removed from the beach due to littoral drift transport, approximately 12,000 m3 of sand and gravel were revealed to be in transit to the northern coast. This quantitative analysis underscores the substantial impact of rocky coastal cliff erosion as a major sedimentary source in a context of limited external sediment supply. The sediment stock, made available for transit and deposition due to local hydrodynamic factors, is notably influenced by a northward longshore drift
En quête de goût. Une histoire des cuisines paysannes poitevines au XVIIIe siècle est-elle possible ?
No full textInternational audienceL’alimentation paysanne à l’époque moderne souffre dans la majorité des publications historiennes d’un désintérêt et d’une représentation dévalorisante. Les pistes de réflexion prônées par Jean-Louis Flandrin ont été peu appliquées à l’alimentation des plus humbles, si bien que d’importantes parts d’ombre subsistent.Pourtant, les obstacles s’opposant à toute étude des pratiques culinaires et gustatives de la paysannerie d’Ancien Régime ne sont pas insurmontables, mais requièrent d’abord un renouvellement des questionnements. En laissant de côté les écueils de la quantification à outrance et de l’approche nutritionniste, il est possible d’adopter une focale davantage culturelle, axée sur les cuisines et les désirs qui leur sont associés. De nombreux sujets peuvent ainsi être abordés, des goûts et dégoûts à l’émergence des cuisines régionales.Pour ce faire, il est nécessaire d’élargir le point de vue du chercheur, autant par le jeu des échelles (du régional au local, voire à la micro-histoire) que par une conception englobante de l’alimentation, de la cuisine ou du plaisir gustatif. Les enjeux de l’alimentation paysanne ne se jouent pas qu’à table, mais dès les champs, et ont des répercussions autant dans de nombreuses pratiques quotidiennes que dans la sociabilité en milieu rural.Cette approche demande un travail particulier sur les sources, notamment par le mélange réfléchi des traitements quantitatifs et qualitatifs. Elle appelle également le croisement de documents d’archives d’origines variées, parfois inattendus. La richesse informationnelle qui en découle est l’illustration de la faisabilité de la relecture culturelle du dossier de l’alimentation paysanne à l’époque moderne
