References of "Toye, Dominique"
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See detailDPSC colonization of functionalized 3D textiles
Ortiz, Marine; Rosales-Ibáñez, R; Pozos-Guillén, A. et al

in Journal of Biomedical Materials Research, Part B : Applied Biomaterials (in press)

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See detailFungal biofilm reactor improves the productivity of hydrophobin HFBII
Khalesi, Mohammadreza; Zune, Quentin ULg; Telek, Samuel ULg et al

in Biochemical Engineering Journal (in press)

Production and purification of hydrophobin HFBII has recently been the subject of intensive research, but the yield of production needs to be further improved for a generic use of this molecule at ... [more ▼]

Production and purification of hydrophobin HFBII has recently been the subject of intensive research, but the yield of production needs to be further improved for a generic use of this molecule at industrial scale. In a first step, the influence of different carbon sources on the growth of Trichoderma reesei and the production of HFBII was investigated. The optimum productivity was obtained by using 40 g/L lactose. Carbon starvation and excretion of extracellular enzyme were determined as two main conditions for the production of HFBII. In the second phase, and according to the physiological mechanisms observed during the screening phase, a bioreactor set up has been designed and two modes of cultures have been investigated, i.e. the classical submerged fermentation and a fungal biofilm reactor. In this last set-up, the broth is continuously recirculated on a metal packing exhibiting a high specific surface. In this case, the fungal biomass was mainly attached to the metal packing, leading to a simplification of downstream processing scheme. More importantly, the HFBII concentration increased up to 48.6 ± 6.2 mg/L which was 1.8 times higher in this reactor configuration and faster than the submerged culture. X-ray tomography analysis shows that the biofilm overgrowth occurs when successive cultures are performed on the same packing. However, this phenomenon has no significant influence on the yield of HFBII, suggesting that this process could be operated in continuous mode. Protein hydrolysis during stationary phase was observed by MALDI-TOF analysis according to the removal of the last amino acid from the structure of HFBII after 48 h from the beginning of fermentation in biofilm reactor. Hopefully this modification does not lead to alternation of the main physicochemical properties of HFBII. [less ▲]

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See detailLarge-Eddy Simulations of microcarrier exposure to potentially damaging eddies inside mini-bioreactors
Collignon, Marie-Laure ULg; Delafosse, Angélique; Calvo, Sébastien ULg et al

in Biochemical Engineering Journal (2016)

Mechanically stirred vessels equipped with rotating impellers generate heterogeneous transitional or turbulent flows. However, some cells as animal or human mesenchymal stem cells (hMSC) adhered on ... [more ▼]

Mechanically stirred vessels equipped with rotating impellers generate heterogeneous transitional or turbulent flows. However, some cells as animal or human mesenchymal stem cells (hMSC) adhered on microcarriers, are reputed sensitive to hydromechanical stresses arising from stirring. Many publications, especially using Computational Fluid Dynamics, characterize spatial fields of velocity and turbulence inside bioreactors but the exposure frequency to these stresses is never taken into account in the case of animal cell culture bioreactor description. To fill this gap, this study used both CFD Reynolds-Averaged and Large-Eddy Simulations to characterize the hydrodynamics inside 250 mL mini-bioreactors, which is a relevant volume for hMSC cultures. Five impeller geometries were studied. From the velocity and turbulence fields calculated, an energy dissipation/circulation function, related to both frequency and intensity of potentially damaging hydrodynamic events for the cells, was determined for various operating conditions. Based on the simulation results, the marine propeller operating in up-pumping mode seems to be the most adapted condition, since it exhibits a low frequency of exposure to an acceptable intensity of the turbulent dissipation rate. From a general point of view, the new methodology proposed should be used in the future to screen the most adapted bioreactor geometry to biological constraints. [less ▲]

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See detailPositive Operations on Wastewater Sludge Drying: Comparison of Back-Mixing and Sawdust Addition
Li, Jie; Plougonven, Erwan ULg; Fraikin, Laurent ULg et al

in Energy & Fuels (2016), 30(4), 3014-3019

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See detailConvective drying behavior of sawdust-sludge mixtures in a fixed bed
Li, Jie; Fraikin, Laurent ULg; Salmon, Thierry ULg et al

in Drying Technology (2016), 34(4), 395-402

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See detailInfluence of process operating conditions on solvent thermal and oxidative degradation in post-combustion CO2 capture
Léonard, Grégoire ULg; Crosset, Cyril; Toye, Dominique ULg et al

in Computers & Chemical Engineering (2015), 83

The CO2 post-combustion capture with amine solvents is modeled as a complex system interconnecting process energy consumption and solvent degradation and emission. Based on own experimental data ... [more ▼]

The CO2 post-combustion capture with amine solvents is modeled as a complex system interconnecting process energy consumption and solvent degradation and emission. Based on own experimental data, monoethanolamine degradation is included into a CO2 capture process model. The influence of operating conditions on solvent loss is validated with pilot plant data from literature. Predicted solvent consumption rates are in better agreement with plant data than any previous work, and pathways are discussed to further refine the model. Oxidative degradation in the absorber is the largest cause of solvent loss while thermal degradation does not appear as a major concern. Using a single model, the process exergy requirement decreases by 10.8% and the solvent loss by 11.1% compared to our base case. As a result, this model provides a practical tool to simultaneously minimize the process energy requirement and the solvent consumption in post-combustion CO2 capture plants with amine solvents. [less ▲]

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See detailFungal biofilm reactor improves the quality of a fusion protein GLA::GFP produced by Aspergillus oryzae
Zune, Quentin ULg; Delepierre, Anissa ULg; Bauwens, Julien ULg et al

Poster (2015, October)

Fungal biofilm is known to promote the excretion of secondary metabolites, in accordance with solid-state related physiological mechanisms. In this work, the potentialities of fungal biofilm will be ... [more ▼]

Fungal biofilm is known to promote the excretion of secondary metabolites, in accordance with solid-state related physiological mechanisms. In this work, the potentialities of fungal biofilm will be investigated in the context of the production of a Gla::GFP fusion protein by Aspergillus oryzae. Since the production of this protein is under the control of the promoter glaB, specifically induced in solid-state fermentation, biofilm mode of culture is expected to enhance the global productivity. However, we found that the glaB promoter is also activated in submerged bioreactor and the fusion protein production is higher in this mode of culture. This result is related to the high shear stress leading to biomass autolysis and leakage of intracellular fusion protein into the extracellular medium. Moreover, 2D-gel electrophoresis highlights preservation of the fusion protein integrity produced in biofilm conditions whereas proteolysis strongly affects fusion protein recovery in the submerged cultures performed at high stirring rate. Fungal biofilm reactor design was then further investigated and the scale-up potentialities were evaluated. Indeed, the specific design investigated in this work involves the use of metal structured packing exhibiting a high specific area and that can be easily expanded to large-scale bioprocessing conditions. [less ▲]

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See detailEuler–Lagrange approach to model heterogeneities in stirred tank bioreactors – Comparison to experimental flow characterization and particle tracking
Delafosse, Angélique ULg; Calvo, Sébastien ULg; Collignon, Marie-Laure ULg et al

in Chemical Engineering Science (2015), 134

The aim of this work is the validation of an Euler–Lagrange modeling approach coupling a CFD-based compartment model (Eulerian approach) and a stochastic model based on a Continuous-Time Markov Chain ... [more ▼]

The aim of this work is the validation of an Euler–Lagrange modeling approach coupling a CFD-based compartment model (Eulerian approach) and a stochastic model based on a Continuous-Time Markov Chain (Lagrangian approach). The turbulent flow structure and the mixing process in a bioreactor stirred by an axial Mixel TT impeller is characterized by PIV and tracer experiments. Comparison between experimental and numerical data shows that the CFD-based compartment model is able to reproduce accurately the spatial heterogeneities inside the bioreactor. The trajectory of a small tracer particle which perfectly follows the fluid flow is measured by optical trajectography. It is then simulated by a stochastic model which is either based on an homogeneous or on an inhomogeneous Continuous Time Markov Chain (CTMC). Comparison of residence and circulation time distributions in three zones defined inside the bioreactor shows that the inhomogeneous CTMC model predicts with an excellent accuracy the particle trajectories inside the bioreactor. The modeling approach proposed here could be an useful tool to design scale-down bioreactors in order to reproduce at lab-scale the stress levels encountered in large-scale production bioreactors and to characterize and compare different bioreactor configurations. [less ▲]

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See detailSurface aeration in baffled stirred tanks: hydrodynamics, mixing and mass transfer characteristics
de Lamotte, Anne ULg; Delafosse, Angélique ULg; Calvo, Sébastien ULg et al

Poster (2015, September)

Biotechnological and chemical processes often need a supply of gas for acceptable product formation. In some applications - where either gas requirements/reactor volumes are relatively low, or bubbles are ... [more ▼]

Biotechnological and chemical processes often need a supply of gas for acceptable product formation. In some applications - where either gas requirements/reactor volumes are relatively low, or bubbles are undesirable - aeration through the liquid free-surface is enough to meet the demand. In case of sparged stirred tanks, aeration through the liquid free-surface is a factor to be determined when scaling-up /down processes. Gas-liquid transfer is strongly influenced by the hydrodynamic conditions. Two phenomena, occurring at different scales, can be coupled in order to explain mass transfer : (i) circulation (macroscale) and (ii) mixing/homogenization (microscale). Mixing/homogenization takes into consideration the small eddies responsible for the rippled liquid free-surface and for the concentration gradients surrounding it. Circulation determines the fluid path across the reactor as well as its contribution of the surface aeration and leads to periodic and local deformation of the liquid free-surface. Circulation also accounts for the design of the reactor, where the scaling problems are focused. The objective of this work is to develop an experimental approach able to fully (global and local quantities) characterize a chosen agitation configuration in terms of hydrodynamics, mixing and transfer, in order to assess the capability of computational methods to predict gas-liquid mass transfer due to aeration through the liquid free-surface. [less ▲]

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See detailMultiscale structure characterization of sawdust-waste water sludge extrudates dried in a pilot-scale fixed bed
Li, Jie ULg; Plougonven, Erwan ULg; Fraikin, Laurent ULg et al

in Biomass and Bioenergy (2015), 81(0), 98-107

Abstract Convective drying of waste water sludge and sawdust-sludge mixtures in a pilot-scale fixed bed was studied. Drying was performed in a cross-flow convective dryer using 500 g of wet material ... [more ▼]

Abstract Convective drying of waste water sludge and sawdust-sludge mixtures in a pilot-scale fixed bed was studied. Drying was performed in a cross-flow convective dryer using 500 g of wet material extruded through a disk with circular dies 12 mm in diameter. The structure of the bed mainly shows volume shrinkage and crack formation during drying. Several characterization techniques were used over a wide range of scales from nm up to mm. The overall bed structure was imaged with X-ray macrotomography, at a resolution of 0.36 mm per pixel. Single extrudates were scanned with X-ray microtomography, at a resolution of 41 μm per pixel. Pore structure of the dried samples were characterized by mercury porosimetry (7.5 nm < dp < 150 μm). Results show significant structural changes on all scales with increasing amounts of sawdust: shrinkage decreases, crack formation increases, and the pores become larger. This confirms the benefits of sawdust addition for sludge drying applications. [less ▲]

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See detailHydrodynamics, mixing and mass transfer in baffled stirred tanks
de Lamotte, Anne ULg; Delafosse, Angélique ULg; Calvo, Sébastien ULg et al

in Proceedings of the 15th European Conference on Mixing (2015, June)

The present work presents CFD simulations of hydrodynamics, mixing and mass transfer in a surface-aerated baffled stirred tank. The modelling of the multiphase flow is realized via an Euler-Euler approach ... [more ▼]

The present work presents CFD simulations of hydrodynamics, mixing and mass transfer in a surface-aerated baffled stirred tank. The modelling of the multiphase flow is realized via an Euler-Euler approach. Three closure models are tested for the resolution of the RANS equations. When fully-developed flow field is reached, gas-liquid transfer is implemented with a local mass transfer coefficient estimated by the eddy cell model, and the temporal evolution of dissolved gas concentration is predicted.Hydrodynamic and mixing quantities as well as mass transfer parameters for the different turbulence models are compared with experimental data available for the same geometrical and operating features. A critical analysis of the prediction results allow to assess the models capabilities and to highlight the possible critical issues of the simulations. [less ▲]

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See detailCatalytic epuration of biogaz
Claude, Vincent ULg; Toye, Dominique ULg; Heinrichs, Benoît ULg et al

Poster (2015, May 08)

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See detailA fungal biofilm reactor based on metal structured packing improves the quality of a Gla::GFP fusion protein produced by Aspergillus oryzae
Zune, Quentin ULg; Delepierre, Anissa ULg; Gofflot, Sebastien et al

in Applied Microbiology and Biotechnology (2015)

Fungal biofilm is known to promote the excretion of secondary metabolites in accordance with solid-state related physiological mechanisms. This work is based on the comparative analysis of classical ... [more ▼]

Fungal biofilm is known to promote the excretion of secondary metabolites in accordance with solid-state related physiological mechanisms. This work is based on the comparative analysis of classical submerged fermentation with a fungal biofilm reactor for the production of a Gla::GFP fusion protein by Aspergillus oryzae. The biofilm reactor comprises a metal structured packing allowing the attachment of the fungal biomass. Since the production of the target protein is under the control of the promoter glaB, specifically induced in solid-state fermentation, the biofilm mode of culture is expected to enhance the global productivity. Although production of the target protein was enhanced by using the biofilm mode of culture, we also found that fusion protein production is also significant when the submerged mode of culture is used. This result is related to high shear stress leading to biomass autolysis and leakage of intracellular fusion protein into the extracellular medium. Moreover, 2D-gel electrophoresis highlights the preservation of fusion protein integrity produced in biofilm conditions. Two fungal biofilm reactor designs were then investigated further, i.e. with full immersion of the packing or with medium recirculation on the packing, and the scale-up potentialities were evaluated. In this context, it has been shown that full immersion of the metal packing in the liquid medium during cultivation allows for a uniform colonization of the packing by the fungal biomass and leads to a better quality of the fusion protein. [less ▲]

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See detailHighly efficient, long life, reusable and robust photosynthetic hybrid core-shell beads for the sustainable production of high value compounds
Desmet, Jonathan; Meunier, Christophe; Danloy, Emeric et al

in Journal of Colloid & Interface Science (2015), 448

An efficient one-step process to synthesize highly porous (Ca-alginate–SiO2–polycation) shell: (Na-alginate– SiO2) core hybrid beads for cell encapsulation, yielding a reusable long-life ... [more ▼]

An efficient one-step process to synthesize highly porous (Ca-alginate–SiO2–polycation) shell: (Na-alginate– SiO2) core hybrid beads for cell encapsulation, yielding a reusable long-life photosynthetically active material for a sustainable manufacture of high-value metabolites is presented. Bead formation is based on crosslinking of an alginate biopolymer and mineralisation of silicic acid in combination with a coacervation process between a polycation and the silica sol, forming a semi-permeable external membrane. The excellent mechanical strength and durability of the monodispersed beads and the control of their porosity and textural properties is achieved by tailoring the silica and alginate loading, polycation concentration and incubation time during coacervation. This process has led to the formation of a remarkably robust hybrid material that confers exceptional protection to live cells against sheer stresses and contamination in a diverse range of applications. Dunaliella tertiolecta encapsulated within this hybrid core–shell system display high photosynthetic activity over a long duration (>1 year). This sustainable biotechnology could find use in high value chemical harvests and biofuel cells to photosynthetic solar cells (energy transformation, electricity production, water splitting technologies). Furthermore the material can be engineered into various forms from spheres to variable thickness films, broadening its potential applications. 2015 Elsevier Inc. All rights reserved. [less ▲]

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See detailCFD Large Eddy Simulation of the hydrodynamics of stirred mini-bioreactors operating with stem cell culture mixing conditions
Collignon, Marie-Laure ULg; Martin, Céline; Toye, Dominique ULg et al

Poster (2015, January 18)

The expansion of hMSC adhered on microcarriers is a proven technology to allow the production of quantitatively (cell density and growth rate) and qualitatively (preservation of cell stemness) the amounts ... [more ▼]

The expansion of hMSC adhered on microcarriers is a proven technology to allow the production of quantitatively (cell density and growth rate) and qualitatively (preservation of cell stemness) the amounts of cells required for clinical applications. In that context of process optimization, a platform of 6 parallel 250 mL stirred minibioreactors have been designed and fully equipped for hMSC cultivation on microcarriers. The local hydrodynamics in these bioreactors have been characterized using CFD simulations and experimental measurements. GOALS: 1) Evaluation of the flexibility of the platform for extensively studying the coupling between hydrodynamics and hMSC physiological response (growth, stemness) by changing agitation conditions. 2) Evaluation of the scale down ability of platform as prediction tool of the hMSC behavior in larger bioreactor scale. [less ▲]

Detailed reference viewed: 86 (7 ULg)