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Unveiling the potential of pullulan in enhancing ketoprofen release from PHBV filaments
No full textInternational audienceIn this study, sustainable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and pullulan (PUL)/PHBV filaments were prepared with ketoprofen for scaffold preparation. The research aimed evaluate the influence of pullulan in the filament properties, such as thermal, morphological, and biological behavior. Hansen parameters demonstrated the difference in the miscibility of the polymers and drug in the blend. This difference in solubility contributed to thermal stabilization, and reduced the crystallinity of the blend, observing a reduction in crystalline peak at 30.82° (002). The morphology change was observed by SEM images, in which ketoprofen appears to smooth and homogenize the filament surface. Cytotoxicity tests on osteoblast cells confirmed that all samples were biocompatible, and the presence of ketoprofen was comparable to the control group. Importantly, the in vitro release of ketoprofen revealed that the presence of pullulan increased the cumulative release of ketoprofen, from 0.1 % to 36 %, within 240 min of the dissolution test. This highlights the crucial role of pullulan in fine-tuning drug release. These findings underscore the potential of these materials for bone regeneration applications, combining the cytotoxic and cell adhesion properties of PHBV with the osteoblasts, and offering precise control over the degradation process and drug release through the incorporation of pullulan
Lignin graphenization using solar concentrated energy
No full textInternational audienceBiomass and biowastes can be used to produce graphitic composite materials using a high temperature process 1 . Graphitic biocomposites are promising materials in many fields (batteries, energy storage, pollution control sensors) thanks to their tunable electrical and thermal conductivity and mechanical properties. The thermal treatment is however quite energy-intensive since it requires temperatures higher than 2000°C. The purpose of this study is thus to produce graphitic biocarbons from biomass using solar carbonization 2 . Lignin (macropolymer of lignocellulosic biomass) is selected as feedstock in this study since its structure is partially aromatic. The sample is placed in a transparent reactor swept by N2, at the focus point of a parabola concentrating the solar radiation on the sample's surface. The graphitization efficiency is studied at temperatures between 1000 °C and 2000 °C using structural,</div
Editorial: Novel reliable approaches for prediction and clinical decision-making in cancer
No full textInternational audienceAlthough significant progress has been made in recent decades in understanding thedevelopment and progression of cancer, cancer remains one of the leading causes of death.Recent insights on immunobiological dysregulations involved in the development andprogression of cancer demonstrate the complexity and heterogeneity of cancer, which playcrucial role in the pharmacokinetic variability of cancer therapies. With regard to theprevalence of recurrence/metastases and prognosis, as well as the prediction of cancertreatment success, further investigations are urgently needed to establish cancer signaturesor treatment modalities that enable improved risk stratification and improved patientmanagement. This Research Topic focuses on studies that integrate new comprehensivesystemic, combinatorial, or complexed data that could be useful to develop personalizedtreatment regimens, to improve immunotherapies and clinical decision-making
Laser metal deposition as repair technology for Inconel 718
No full textInternational audienceFrom an economic and sustainability point of view, repair is considered a promising alternative for high value-added aeronautical materials. In this study, laser metal deposition (LMD) was used for simulating the repair of damaged Inconel 718 (IN718) parts. Grooves were machined in IN718 substrates using abrasive water jet (AWJ) and filled with powdered IN718 alloy. Based on these results, a set of optimal LMD process parameters were selected for depositing material layers on milled substrates with various of roughness and texture levels induced by AWJ machining to evaluate the effect of surface preparation on repair quality. The substrate-deposit repair interfaces were characterized using microscopic analysis and multi-scale hardness tests. The results showed the influence of scan speed on the height of the weld bead, while increasing laser power and scan speed were both found to increase weld bead height. Dilution increased with a decrease in scan speed. Additionally, repair quality was found to be independent of the different surface conditions. Overall, the repairs exhibited excellent weldability, and were free of cracks and lack-of-fusion defects. Furthermore, microhardness measurements yielded higher values of hardness in the deposit area than in the substrate for all repairs
Effect of fiber surface state on the thermomechanical and interfacial properties of in situ polymerized polyamide 6/basalt fiber composites
No full textInternational audienceThis study investigates the thermomechanical properties and interfacial adhesion of novel in-situ polymerized anionic polyamide 6 (aPA6) composites reinforced with basalt fibers (BF). The impact of different BF surface states - as-received (BFa), ethanol-washed (BFw), and thermally desized (BFu) − on composite performance is examined through a comprehensive approach. For the first time, anionic PA6/BF composites with very low residual monomer content were successfully produced via thermoplastic resin transfer molding (tRTM). The PA6/BFw composites exhibited the highest interlaminar/interfacial shear strength in short beam shear test (52 ± 8 MPa) and fiber push out test (34 ± 11 MPa) tests. Fiber microdebonding test, performed only on PA6/BFw, yielded a low interfacial shear strength (12 ± 4 MPa), which was attributed to droplet porosity resulting from concurrent polymerization and crystallization. Thermal desizing significantly deteriorated interfacial strength (19.6 ± 1.2 MPa in short beam shear test). This multi-technique characterization provides insights into optimizing the fiber–matrix adhesion in these advanced thermoplastic composites
Investigation of vapor liquid equilibria for HFO-1336mzz(E) + HFC-1234ze(E) binary system by a novel developed cyclic-analytical apparatus
No full textInternational audienceHydrofluoroolefins (HFOs), which have excellent thermophysical properties and environmental performance, are considered as the most promising environmentally friendly alternatives to the currently used refrigerants. The vapor-liquid equilibrium (VLE) properties of fluids are the basis for the design and optimization of chemical separation and refrigeration systems. In this work, a high-precision and visual VLE experimental apparatus was developed based on the cyclic-analytical method. which mainly includes thermostatic bath, VLE cell, temperature and pressure measurement system, and gas chromatograph, etc. The expanded uncertainties of temperature, pressure, and composition measurement are 0.06 K, 0.0086 MPa, and 0.056 mole fraction, respectively. By measuring the VLE data of the known binary system and comparing it with the literature, the reliability and accuracy of the experimental apparatus were verified. The VLE data of HFO-1336mzz(E) + HFC-1234ze(E) were measured in the temperature range of 293.15 to 358.15 K. The experimental data were correlated with the Peng Robinson (PR) equation of state (EoS) combined with Mathias-Copeman alpha function (MC) and van der Waals (vdW) mixing rule (PRMC-vdW model) in order to adjust the binary interaction parameters (BIP). The VLE data was also compared with the PPR78 predictive model. The VLE investigation provides a basis for further research on the cycle performance of the mixed working fluid
Étude de l'influence des phénomènes thermomécaniques générés par l'interaction faisceau laser matière sur la microstructure des revêtements élaborés par SLM : une approche multi-physique
No full textThe aim of this study is to investigate the advection/convection mechanisms that occur during the additive manufacturing process on dissimilar materials. More specifically for this research, a group of materials which have distinct thermophysical characteristics, but which have the advantage of being perfectly miscible at high temperatures : - C35 (or XC38) steel is a material frequently used in manufacturing tools - Cobalt-Chromium-Molybdenum alloy for applications requiring high resistance to wear and high temperatures. The first part of this study focuses on the description of the stellite alloy, as it is barely characterized in terms of its thermal characteristics, especially at high temperatures. The multiphysics numerical models developed in the study provide access to a large amount of information on the behavior of the molten region as a function of the parameters of the FA L-PBF machine, with reference to a relatively small amount of initial data and a few basic assumptions. Multiphysics modeling is used to replicate the shape of the molten zone, visualize the flow of liquid metal and map the distribution of the various elements, taking into account the experimental results. To implement these manufacturing process models, we use the commercial simulation software COMSOL Multiphysics® . A series of models have been developed to simulate temperature variations, convective movements and chemical mixing. All these models enable us to predict the results of the various phenomena induced as a function of operating conditions.Cette étude vise à étudier les mécanismes d'advections/convections qui se produisent lors du processus de fabrication additive L-PBF sur des matériaux différents. Plus spécifiquement pour cette recherche, un ensemble de matériaux qui ont des caractéristiques thermophysiques distinctes, mais qui ont l'avantage d'être parfaitement miscibles à haute température : - l'acier C35 (ou XC38) qui est un matériau usuellement utilisé pour l'outillage- l'alliage stellite (composé de cobalt, de chrome et de molybdène) est un alliage adéquat pour les applications nécessitant de fortes caractéristiques en termes d'usure et de bonne tenue en température. Le premier aspect de cette étude se concentre sur la description de l'alliage de stellite, car il est très peu caractérisé en ce qui concerne ses caractéristiques thermiques, notamment à des températures élevées. Pour cela, des caractérisations sur les propriétés thermiques de la poudre ont été effectuées pour la capacité calorifique, la diffusivité thermique et la masse volumique de la poudre. En complément de ces mesures, une attention plus particulière sur les caractérisations thermo-optiques de la poudre et de l'alliage de stellite a été menée, notamment sur l'absorptivité et l'émissivité. L'utilisation des modèles numériques multiphysiques développés lors de cette étude permet d'accéder rapidement à une grande quantité d'informations sur le comportement de la zone fondue en fonction des paramètres de la machine FA L-PBF en se référant à un nombre de données de départ relativement restreint et à quelques hypothèses basiques. La modélisation multiphysique permet de reproduire la forme de la zone fondue, de visualiser les flux de métal liquide et de cartographier la répartition des différents éléments en tenant compte des résultats expérimentaux. Afin de mettre en œuvre ces modèles de procédé de fabrication, nous utilisons le logiciel de simulation commercial COMSOL Multiphysics. On a développé une série de modèles qui simulent les variations de température, les mouvements convectifs et le mélange des substances chimiques. Tous ces modèles permettent de prévoir les résultats des divers phénomènes induits en fonction des conditions opératoires
Effect of Ru Doping on the Performance of Na‐Promoted Co/TiO 2 Catalysts for Direct CO 2 Hydrogenation to Fuels
No full textInternational audienceThe direct conversion of CO 2 into fuels via hydrogenation represents a promising solution to the storage of renewable energy. This reaction generally proceeds through the reverse water gas shift (RWGS) reaction to produce CO and the subsequent CO‐Fischer–Tropsch synthesis (FTS). On Co‐based catalysts, the introduction of dopants can improve CO 2 activation, enhance the RWGS activity, and decrease the methanation reaction. We reported that Na‐promoted Co/TiO 2 catalysts outperform the unpromoted ones in terms of activity and selectivity toward C 2+ . To further improve the catalytic performances, we doped a Na‐promoted Co/TiO 2 catalyst with ruthenium, which is known to favor a high degree of cobalt reduction in CO‐FTS. The effect of Ru location in relation to cobalt was investigated by using bimetallic and mixtures of monometallic catalysts. This study demonstrates that Ru doping leads to an improvement in catalytic activity. Furthermore, we show that the proximity between Co and Ru has a pronounced effect on the selectivity. The best configuration to achieve higher CO 2 conversion and C 5+ selectivity is obtained using mixtures of monometallic catalysts separated in two beds. Reducing the Ru loading significantly improved the selectivity toward C 2 ‐C 4 hydrocarbons
Transforming printed electronic paper waste into eco-friendly adsorbents for gas effluents purification
No full textInternational audienceDue to the integration of more sustainable technologies, printed electronic devices have been emerging in markets such as packaging, magazines, and labels. These devices offer an eco-friendly alternative to traditional electronics by using less harmful materials such as paper and textiles, and conductive inks, primarily composed of silver. Nevertheless, as the production of such devices grows, concerns about their end-of-life, recyclability, and environmental impact emerge. As a result, the project which aligns with the European Green Deal and circular economy principles, aims to convert printed electronic paper residues into porous materials employing hydrothermal carbonization (HTC). The HTC process was optimized by adjusting paper-to-water ratios, temperature, and retention time. Besides that, ICP-OES analysis confirmed the effective immobilization of the metal within the carbon matrix, highlighting its potential for resource recovery. Hydrochars produced were activated with KOH to improve their sorptive properties and further studies will be done to determine the material's potential for gas purification
The Influence of Microstructural Heterogeneities on the Thermal Response of CFRTP Composite Tapes at the Ply-Scale
No full textInternational audienceThe thermal response of Carbon Fiber Reinforced Thermoplastic (CFRTP) tapes under short-term localized heating is critical for automated manufacturing processes. Conventional homogenized models often overlook microstructural heterogeneities that can promote non-uniform heating and affect the quality of the consolidated part. In this work, we combine insights from infrared thermography with finite element simulations at the fiber scale built on micrographs extracted from real tapes to quantify the effect of individual heterogeneities—including surface roughness, thickness variation, fiber agglomeration, and porosity—on thermal propagation. Three modeling configurations were compared under identical conditions: a full microstructure model; a simplified geometry-aware model (where the real geometry is taken into the account, including the surface roughness and thickness variability, but the properties of the domain are considered as a homogeneous-equivalent material); and a homogeneous-equivalent baseline with flat borders and uniform thickness. Results show that porosity effects depend strongly on location and orientation: large, horizontally aligned pores near the heated surface produce the highest gradients. Surface roughness, on the other hand, exerts dominant effects on surface temperature non-uniformity with respect to thickness variation and fiber distribution. These findings demonstrate that accounting for microscale heterogeneities is essential to achieve more accurate, optimized, and application-tailored analyses of CFRTP tapes in advanced manufacturing