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Improving the Synthesis of Odd-Chain Fatty Acids in the Oleaginous Yeast Yarrowia lipolytica
No full textInternational audience(1) Background: Odd-chain fatty acids (OCFAs) have garnered attention for their potential health benefits and unique roles in various biochemical pathways. Yarrowia lipolytica, a versatile yeast species, is increasingly studied for its capability to produce OCFAs under controlled genetic and environmental conditions. However, optimizing the synthesis of specific OCFAs, such as cis-9-heptadecenoic acid (C17:1), remains a challenge. (2) Methods: The gene coding for the Δ9 fatty acid desaturase, YlOLE1, and the gene coding the diacylglycerol O-acyltransferase 2, YlDGA2, were overexpressed in Y. lipolytica. With the engineered strain, the main goal was to fine-tune the production of OCFA-enriched lipids by optimizing the concentrations of sodium propionate and sodium acetate used as precursors for synthesizing odd- and even-chain fatty acids, respectively. (3) Results: In the strain overexpressing only YlDGA2, no significant changes in fatty acid composition or lipid content were observed compared to the control strain. However, in the strain overexpressing both genes, while no significant changes in lipid content were noted, a significant increase was observed in OCFA content. The optimal conditions for maximizing the cell density and the C17:1 content in lipids were found to be 2.23 g/L of sodium propionate and 17.48 g/L of sodium acetate. These conditions resulted in a cell density (optical density at 600 nm) of 19.5 ± 0.46 and a C17:1 content of 45.56% ± 1.29 in the culture medium after 168 h of fermentation. (4) Conclusions: By overexpressing the YlOLE1 gene and optimizing the concentrations of fatty acid precursors, it was possible to increase the content of OCFAs, mainly C17:1, in lipids synthesized by Y. lipolytica
Optimized Extraction of Polyphenols from Kiwifruit Peels and Their Biological Activities
No full textInternational audience(1) Background: Kiwifruit is a globally valued fruit. Its industrial processing produces a substantial amount of waste, particularly peels, which present an appealing potential source of bioactive compounds. This study focuses on optimizing the extraction of phenolics from kiwi peels using a water bath (WB) and infrared irradiation (IR) and assessing their biological activities. (2) Methods: Optimal conditions for polyphenol extraction from kiwifruit peels, in terms of temperature and time, were determined using Response Surface Methodology. Total phenolic content (TPC) was measured by the Folin–Ciocalteu method, and antioxidant activity was assessed utilizing the DPPH method. Antibacterial activities against Bacillus cereus, Staphylococcus aureus, Escherichia coli, and Salmonella Typhimurium were determined using the minimum inhibitory concentration (MIC). The lyophilized extract was tested for its anticancer effect on A549 lung cancer cell lines. The phytochemical profiles of the WB and IR extracts were analyzed through High-Performance Liquid Chromatography (HPLC). (3) Results: The optimal extraction conditions for the WB method were found to be 75 °C for 35 min, and 90 °C for 5 min for IR. The corresponding TPC obtained by IR was 21 mg GAE/g DM, which was 4.4 times higher than that obtained by WB (4.8 mg GAE/g DM). This indicates that IR was more efficient in extracting phenolics from kiwi peels. The antioxidant activity under the optimum conditions of WB and IR was 14 mg TE/g DM and 16 mg TE/g DM, respectively. Both the WB and IR extracts demonstrated antibacterial activity against B. cereus with an MIC value of 25 mg/mL. Additionally, the IR extract displayed an antibacterial effect against S. aureus, with an MIC value of 50 mg/mL. The WB and IR kiwi peel extracts were effective in significantly reducing A549 cell viability at 50 µg/mL and 100 µg/mL, respectively. Caffeic acid (0.54 ppm) and catechin (5.44 ppm) were the major polyphenols identified in WB and IR extracts, as determined by HPLC. (4) Conclusions: IR was more efficient in extracting phenolics from kiwi peels than WB. The findings also suggest that kiwi peel can be effectively utilized as an antioxidant, antibacterial, and anticancer agent
Comparing sequential and integrated models in Reconfigurable Manufacturing Systems optimization
No full textInternational audienceConsumers are increasingly seeking products with a higher degree of customization, and this has intensified the search for more flexible production systems. Unexpected phenomena, including those impacting the economy and public health, have shown the need for high reactivity by manufacturers. Reconfigurable Manufacturing Systems are one of the means to respond to new market needs. They are designed to be able to quickly change their structure and thus adapt their functionalities and capabilities. A central question with regard to these types of systems is when and how they should be reconfigured. It is, however, a question that needs to be addressed simultaneously alongside the classic resource allocation and scheduling problems, since the problems are interdependent. This paper proposes four models that address the problem sequentially, partially sequentially, and integrally. Our numerical analysis demonstrates the advantage and importance of treating these problems in an integrated manner. In addition, we provide and compare three exact methods for the integrated process planning, layout, and scheduling optimization problems. The exact methods are integer linear programming, constraint programming, and constraint programming with search strategies, which our numerical examples show to be greatly superior to the two others. Finally, we present a problem at an industrial scale
A 3D frequency domain finite element formulation for solving the wave equation in the presence of rotating obstacles
No full textInternational audienceA frequency domain numerical method aimed at solving the propagation of sound waves in a three-dimensional domain enclosing rotating obstacles is presented. It relies on a domain decomposition whereby rotating parts are all embedded in a cylindrically-shaped domain. Following the classical Arbitrary Lagrangian Eulerian formalism, the governing equation, which is written in the local rotating frame, takes the form of a convected wave equation. The transmission conditions at the interface between the fixed and rotating domains is accomplished via the Frequency Scattering Boundary Conditions which, after classical FEM discretization, give rise to a series of coupled problems associated with a discrete set of frequencies. The performances of the method are demonstrated through several test cases involving rotating sources and/or obstacles inserted in circular and rectangular ducts
Optimisation des outils d’emboutissage à chaud obtenus par la fabrication additive
No full textHot stamping is widely used in automotive part manufacturing. The hot stamping tool is critical, as it not only shapes the parts but also controls their cooling rate. This thesis explores developing an efficient design method for high-performance, cost-effective, and reliable hot stamping tools using metal additive manufacturing. The primary goal is to reduce tool cooling time, thereby increasing productivity.L'emboutissage à chaud est un procédé très utilisé pour la fabrication des pièces automobiles. L'outil d'emboutissage revêt une importance particulière. Il a non seulement la fonction de mise en forme, mais contrôle également la vitesse de refroidissement des pièces. Cette thèse porte sur le développement d'une procédure de conception rationnelle des outils d'emboutissage à chaud performants, plus économiques et fiables grâce à fabrication additive métallique. L'objectif principal est de réduire le temps de refroidissement dans l’outil d'emboutissage à chaud pour augmenter la productivité
Phosphorylated chitin from shrimp shell waste: A robust solution for cadmium remediation
No full textInternational audienceIn this work, chitin (CT) was isolated from shrimp shell waste (SSW) and was then phosphorylated using diammonium hydrogen phosphate (DAP) as a phosphorylating agent in the presence of urea. The prepared samples were characterized using Scanning Electron Microscopy (SEM) and EDX-element mapping, Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA/DTG), conductometric titration, Degree of Substitution (DS) and contact angle measurements. The results of characterization techniques reveal the successful extraction and phosphorylation of chitin. The charge content of the phosphorylated chitin (P-CT) was 1.510 mmol·kg−1, the degree of substitution of phosphorus groups grafted on the CT surface achieved the value of 0.33. The adsorption mechanisms appeared to involve electrostatic attachment, specific adsorption (Cdsingle bondO or hydroxyl binding), and ion exchange. Regarding the adsorption of Cd2+, the effect of the adsorbent mass, initial concentration of Cd2+, contact time, pH, and temperature were studied in batch experiments, and optimum values for each parameter were identified. The experimental results revealed that P-CT enhanced the Cd2+ removal capacity by 17.5 %. The kinetic analyses favored the pseudo-second-order model over the pseudo-first-order model for describing the adsorption process accurately. Langmuir model aptly represented the adsorption isotherms, suggesting unimolecular layer adsorption with a maximum capacity of 62.71 mg·g−1 under optimal conditions of 30 °C, 120 min, pH 8, and a P-CT dose of 3 g·L−1. Regeneration experiments evidenced that P-CT can be used for 6 cycles without significant removal capacity loss. Consequently, P-CT presents an efficient and cost-effective potential biosorbent for Cd2+ removal in wastewater treatment applications
A conditioned local limit theorem for non-negative random matrices
No full textInternational audienceLet be the random process on driven by the product of i.i.d. non-negative random matrices and its exit time from . By using the adapted strategy initiated by D. Denisov and V. Wachtel, we obtain an asymptotic estimate and bounds of the probability that the process remains non negative up to time and simultaneously belongs to some compact set at time
Couplage Hydro-cinétique de méthodes numériques pour modéliser le comportement de réacteurs pilotes complexes : Application aux méthaniseurs en voie solide
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Wind turbine components’ life cycle assessment for eco-design purposes: state of the art
No full textInternational audienceThe maintenance of the wind turbine generator has a crucial importance on the sustainable operation and energy production of the wind turbines on long-term. The optimal design of the wind turbine components has a direct impact on satisfying sustainability objectives on the renewable energy production. In these perspectives, the vibration analysis is one of the vital aspects for the operation of wind turbines, which enables to realize the predictive maintenance of the equipment. This analysis induces the use of the piezoelectric transducers, possibility in the form of the IoT, which can also have a significant environmental impact. In this paper, a state-of-art of the latest researches on piezoelectric transducers are carried on in order to present a framework that proposes the eco-design and predictive maintenance of the wind turbines in order to improve the sustainable operation considering their environmental impacts
Application de la méthode 5S en Ingénierie Biomédicale
No full textCe Mémoire d’Intelligence Méthodologique explore l'applicabilité de la méthode 5S, originellement issue du système de production japonais, dans le contexte de l'ingénierie biomédicale. L'objectif est d'améliorer l'efficacité opérationnelle, la qualité des services et la sécurité des dispositifs médicaux au sein des établissements de santé français. La méthode 5S, comprenant les étapes de tri, de rangement, de nettoyage, de standardisation et de suivi, offre un cadre structuré pour l'organisation des espaces de travail d’un atelier biomédical. Les deux premières parties examinent les spécificités de l'ingénierie biomédicale (applicables grâce à la méthode 5S), identifient les défis auxquels cette discipline est confrontée en termes de gestion des locaux, gestion des dispositifs médicaux, de traçabilité ou encore de maintenance et proposent un outil permettant d’aider les services biomédicaux à mieux gérer leurs locaux. La dernière partie se concentre sur la proposition d'une nouvelle Bonne Pratique d'Activité Connexe (BPAC) adaptée à l'ingénierie biomédicale. Cette BPAC, serait élaborée en tenant compte des spécificités du secteur, visant à renforcer les normes de qualité, de sécurité et de traçabilité. Elle proposerait des lignes directrices détaillées pour l'application des 5S, en mettant l'accent sur la rédaction de procédures, la définition de zones de stockage et l'évaluation continue des processus