Gradient methods for problems with inexact model of the objective

We consider optimization methods for convex minimization problems under inexact information on the objective function. We introduce inexact model of the objective, which as a particular cases includes inexact oracle [19] and relative smoothness condition [43]. We analyze gradient method which uses this inexact model and obtain convergence rates for convex and strongly convex problems. To show potential applications of our general framework we consider three particular problems. The first one is clustering by electorial model introduced in [49]. The second one is approximating optimal transport distance, for which we propose a Proximal Sinkhorn algorithm. The third one is devoted to approximating optimal transport barycenter and we propose a Proximal Iterative Bregman Projections algorithm. We also illustrate the practical performance of our algorithms by numerical experiments

Investigation of growth limitation by CO2 mass transfer and inorganic carbon source for the microalga Chlorella vulgaris in a dedicated photobioreactor

International audienceh i g h l i g h t s An experiment was set up to characterize the CO 2 assimilation by microalgae. Accurate time monitoring of the various carbon fluxes was validated. Carbon fluxes were modeled to determine on-line k L a. k L a value was found to be affected by the presence of cells. Growth rate was found to be related to the gas-liquid mass transfer rate

Microalgae culture in building-integrated photobioreactors: Biomass production modelling and energetic analysis

International audienceVertical flat-panel photobioreactors for microalgae culture can be integrated into building facades. On top of providing the large solar illuminated surfaces needed for microalgae production, this original combination opens various optimization opportunities, such as the possibility to create mutual benefits for both systems with appropriate and efficient integration. For example, microalgal photosynthesis can be used to fix the CO2 contained in flue gas emitted from the building (in a factory set-up) or to significantly reduce energy consumption for thermal regulation of both photobioreactors and building.Here we report the results of a theoretical modelling-based investigation designed to define how the specific building integration conditions affect photobioreactor operation. Expected biomass production and light attenuation conditions encountered in the culture volume were determined for the green microalgae Chlorella vulgaris for a location based in Nantes (France). Results were compared to figures from the more conventional systems such as horizontal or ideally-inclined microalgal culture systems. We conclude with an energetic analysis that underlines the relevance of optimizing thermal exchanges between microalgal culture and building

Development and validation of a screening procedure of microalgae for biodiesel production: Application to the genus of marine microalgae Nannochloropsis

International audienc

Identification and characterisation of peptides from a boarfish (Capros aper) protein hydrolysate displaying in vitro dipeptidyl peptidase-IV (DPP-IV) inhibitory and insulinotropic activity

Twenty-two novel dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides (with IC50 values <200 µM) and fifteen novel insulinotropic peptides were identified in a boarfish protein hydrolysate generated at semi-pilot scale using Alcalase 2.4L and Flavourzyme 500L. This was achieved by bioassay-driven semi preparative reverse phase-high performance liquid chromatography fractionation, liquid chromatography-mass spectrometry and confirmatory studies with synthetic peptides. The most potent DPP-IV inhibitory peptide (IPVDM) had a DPP-IV half maximal inhibitory concentration (IC50) values of 21.72 ± 1.08 µM in a conventional in vitro and 44.26 ± 0.65 µM in an in situ cell-based (Caco 2) DPP-IV inhibition assay. Furthermore, this peptide stimulated potent insulin secretory activity (1.6 fold increase compared to control) from pancreatic BRIN-BD11 cells grown in culture. The tripeptide IPV exhibited potent DPP-IV inhibitory activity (IC50: 5.61 ± 0.20 µM) comparable to that reported for the known DPP-IV inhibitor IPI (IC50: 5.61 µM). Boarfish proteins contain peptide sequences with potential to play a role in glycaemic management in vivo