Transposition from a batch to a continuous process for microencapsulation by interfacial polycondensation

A novel continuous process is proposed and investigated to produce microcapsules by interfacial polycondensation. Polymeric microcapsules are obtained via a two-step process including an initial emulsification of two immiscible fluids in static mixers and a subsequent interfacial polycondensation reaction performed in two different continuous reactors, the Deanhex heat exchanger/reactor or a classical coiledtube. This study is carried out through a step by step approach. A model system involving polyurea as the polymeric membrane and cyclohexane as the encapsulated species is chosen. A semi-batch reaction kinetic study is first performed in order to obtain kinetics data of the polycondensation reaction and to highlight hydrodynamic issues that can happen when running the encapsulation reaction in classical stirred tank. Parameters influencing droplets size obtained when carrying out emulsification in static mixers are then investigated. The hydrodynamic of the Deanhex reactor used is also characterized in terms of mixing time and residence time distribution. To validate the innovative continuous process, the emulsion droplets obtained at the static mixer outlet are encapsulated firstly in the Deanhex reactor and secondly in the coiled-tube. The apparent reaction kinetics and microcapsules characteristics corresponding to different operating conditions are discussed

QTL for resistance to Trichoderma lytic enzymes and metabolites in Agaricus bisporus

National audienceTrichoderma aggressivum leads to severe crop losses in Agaricus bisporus cultures. The development of strain resistant to this competitor is an alternative to the use of chemicals. One of the interacting components of the putative system of resistance is the lack of susceptibility to the growth limiting compounds produced by Trichoderma sp. Wide variation for this trait has been previously demonstrated, with few strains able to resist to Trichoderma lytic enzymes and metabolites. For exploiting such a resistance in breeding programs, the knowledge of its genetic basis is a prerequisite. Therefore, QTL analysis was used to determine the number, effects and location of genomic regions associated with tolerance to Trichoderma lytic enzymes and metabolites in a hybrid progeny of A. bisporus. An in vitro experiment using sequential cultures on media supplemented or not with a commercial product Lysing Enzyme was used. The mycelium growth rate in control condition, the level of tolerance and the capacity of adaptation were the traits used for QTL detection. In total for all the traits, seven QTLs were detected distributed on four genomic regions. Two clusters of QTLs related to several traits and two other trait-specific QTLs were identified. A genomic region on LGIV was detected for each trait, with the highest LOD score value and genetic effects. Our results showed that tolerance to Trichoderma lytic enzymes and metabolites was tightly related to mycelium growth ability. Consequences for mushroom breeding program are discussed

Cartography of liquid-liquid flow in corrugated millichannels

International audienceIf the interest of continuous heat exchanger/reactors have been demonstrated for homogeneous liquid phase applications, many chemical syntheses take place in multiphase media (gas-liquid, liquid-liquid, gas-liquid-solid...). Thus, in order to evaluate the versatility criterion of a plate-type heat exchanger/reactor with a 2D-meandering millichannel, this work is focused on the characterization of hydrodynamics of liquid-liquid two-phase flow in the reaction channel. For this purpose, several prototypes have been built with different millichannels of increasing dimensions to address as well the scale-up issue. Flow visualizations are performed by using a high-speed camera; four flow regimes with octanol/water fluid system are observed: annular/plug, annular, annular/dispersed, and dispersed flows. The study shows that the interfacial tension and the dispersed phase inertia are the main forces that drive the interface. A dimensionless map based on the Weber number of the dispersed phase as a function of the internal Dean number of the continuous phase is built up. This map turns out to be valid regardless of the size of the corrugated millichannel

Liquid-liquid flow in a corrugated channel: hydrodynamics and transfer

International audienceMilli-structured heat exchanger/reactors are promising for theimplementation of chemical syntheses, especially rapid andexothermic ones. In the case of multiphase reactions, mass transfercan become the limiting step controlling the chemical reaction.Therefore, this work aims at characterizing the flow and the liquidliquid mass transfer in the millichannel of the "DeanHex"exchanger/reactor in order to build a complete model of this devicecapable of predicting its performances at an industrial scale.MethodsExperimental studies (hydrodynamics and mass transfer) areconducted in three zigzag millichannels of square cross-sections(hydraulic diameters d$_h$ = 2, 3 and 4 mm). Water/rhodamine B(RhB)/octanol fluid system is used. The flow is visualised fordifferent flowrates of the phases. The transfer of RhB from water tooctanol is then investigated for different total flowrates (1.5 to 6kg‧h-1) and flowrates ratios "q" (0.5 to 2). At the reactor outlet,based on the wettability of liquids to a given solid material, theorganic phase is extracted and analyzed by UV-Vis spectrometry.Results and discussionFour types of flow regimes are observed in the threemillichannels (Figure 1). A flow patterns map based on the Webernumber of the dispersed phase "Weaq" and the internal Dean numberof the continuous phase "Deiorg" is proposed, as shown in Figure

Shell-and-tube heat exchanger geometry modification: An efficient way to mitigate fouling

International audienceCrude oil fouling of a shell-and-tube heat exchanger sized according to TEMA standard is compared to a No-Foul design under industrial operating conditions. For similar operating conditions, TEMA and No-Foul heat exchangers have the same behavior regarding fouling. Since the No-Foul one has less tubes by design for the same heat duty, shear stress is increased. Consequently, the No-Foul heat exchanger is less prone to fouling at the same throughput. Impact of tube bundle geometry is then investigated. Helicallyfinned tubes are compared to plain tubes in the No-Foul heat exchanger. Under similar operating conditions, fouling rates measured are up to an order of magnitude lower than plain tubes (respectively 10$^{-11}$ and 10$^{-10}$ m$^2$ K/J). However, pressure drop across the tube-side in both No-Foul plain and finned setup are increased in comparison to the TEMA heat-exchanger

Liquid-liquid flow in a corrugated channel: hydrodynamics and transfer

International audienceMilli-structured heat exchanger/reactors are promising for theimplementation of chemical syntheses, especially rapid andexothermic ones. In the case of multiphase reactions, mass transfercan become the limiting step controlling the chemical reaction.Therefore, this work aims at characterizing the flow and the liquidliquid mass transfer in the millichannel of the "DeanHex"exchanger/reactor in order to build a complete model of this devicecapable of predicting its performances at an industrial scale.MethodsExperimental studies (hydrodynamics and mass transfer) areconducted in three zigzag millichannels of square cross-sections(hydraulic diameters d$_h$ = 2, 3 and 4 mm). Water/rhodamine B(RhB)/octanol fluid system is used. The flow is visualised fordifferent flowrates of the phases. The transfer of RhB from water tooctanol is then investigated for different total flowrates (1.5 to 6kg‧h-1) and flowrates ratios "q" (0.5 to 2). At the reactor outlet,based on the wettability of liquids to a given solid material, theorganic phase is extracted and analyzed by UV-Vis spectrometry.Results and discussionFour types of flow regimes are observed in the threemillichannels (Figure 1). A flow patterns map based on the Webernumber of the dispersed phase "Weaq" and the internal Dean numberof the continuous phase "Deiorg" is proposed, as shown in Figure

Numerical Investigation of the Heat Transfer in a Meandering Millichannel by a coupled 1D-Flow-Channel / 3D-Surrounding-Solid Model

International audienceHeat exchanger/reactors with corrugated channels are used to implement especially exothermal chemical reactions. Heat conduction effects in their solid material are not negligible and induce in particular heat flows between adjacent channels. In this context, this work proposes a model of a platetype heat exchanger/reactor with a 2D-meandering millichannel, taking into account these conduction effects by coupling a 1D approach for the channel flow, with correlations for the friction factor and the Nusselt number, to a 3D approach for the solid part. This model is a compromise between the 1D classical reactor models that don't account for 3D conduction effects in the solid and the 3D simulations of the channel flow with the surrounding solid which are computationnally expensive or unachievable for a large reactor. In the tested case, the 1D/3D and 3D CFD results are in good agreement (5 min vs 4 h computational time), which suggests valid model assumptions and internal model consistency. Simulated and experimental conversion rates of a fast highly exothermic reaction are then compared, showing the relevancy of the model. Further investigations are performed to highlight the effect of conjugate heat transfer in millistructured heat exchangers and to quantify its limitations versus the 1D/3D model

Semantic knowledge of newly coined words in mild cognitive impariment and Alzheimer's disease

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A family of low and high copy replicative, integrative and single-strandedS. cerevisiae/E. coli shuttle vectors

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Changes in antioxidant activities and compounds during cultivation of shiitake ( Lentinula edodes)

National audienceMushrooms contain a variety of secondary metabolites, including various phenolic compounds, which have been shown to act as excellent antioxidants. Recently, a specific antioxidant, ergothioneine (ERG) has been identified in various genera of mushrooms, including shiitake ( Lentinula edodes). Shiitake is the second most highly consumed mushroom in the world, and present several functional properties, such as antitumor, hypocholesterolemic, antioxidant and antimicrobial potentials that have been intensively investigated. Although research was focused on its therapeutic effects, little information is available about the compounds responsible of the antioxidant properties. Our objectives were to identify changes in quality of shiitake as antioxidant source during cultivation cycles on oak woodships. The antioxidant activities and contents of potential antioxidant components, including total phenolic (TP) compounds and ERG, were analyzed in two parts of mushrooms (stipe and cap) from the successive flushes. In addition, the seasonal variations were studied. The Folin-Ciocalteu reagent was used to quantify the TP, and ERG was quantified by HPLC-DAD. The antioxidant activity was measured using the ORAC assay. Our analysis revealed only minor seasonal variations in TP and ERG contents as well as the ORAC value, excepted during the winter where these contents were 50% higher in the caps. Regarding the age of the culture, we observed a progressive decrease in the contents of TP and ERG all along the flushes, whatever the part of the mushroom. Surprisingly, the ORAC value increased in the whole mushrooms, whereas it decreased in the caps and strongly increased in the stipes. We concluded that the antioxidant activities could be largely dependent on other molecules than ERG, perhaps specific phenolic compounds. Having established the main variations in the antioxidant activity of shiitake, the chemical characteristics of the antioxidative components will be now further investigated. This study could provide valuable new opportunities for mushroom growers, since shiitake can serve as a good source of antioxidants in the human diet