Assessment of Antioxidant and Antibacterial Activities of Cystoseira mediterranea and Padina pavonica from Algerian North-East for a Potential Use as a Food Preservative

The aim of this work was to evaluate the antioxidant and antibacterial activities of two marine algae, Cystoseira mediterranea and Padina pavonica, extracts. Total phenols (TPC), carotenoids, and phlorotannins contents of the extracts obtained by four extraction solvents were determined and compared. The highest TPC content was observed for aqueous extract of C. mediterranea with 37.09±0.46 mg GAE/g DE followed by ethanol extract of P. pavonica (24.28±0.99 mg GAE/g DE), which showed the highest phlorotannins content (1.18±0.18 mg PE/g DE), while its methanol extract held carotenoids content of 66.96±4.78 μg g–1 DE. Ethanol extract of C. mediterranea exhibited the best antioxidant activity with an EC50 of 58.3±1.16 μg ml–1. The antibacterial activity screening against MRSA and E. coli showed that ethanol extract of C. mediterranea towards a Methicillin resistant Staphyloccocus aureus (20.33±0.28 mm) and E. coli (15.66±0.57 mm) was more efficient with MICs about 80 mg ml–1 and 20 mg ml–1, respectively. Ethanol extract of C. mediterranea seems to have the highest potential for use in food industries

Effect of viscosity gradients on mean velocity profile in temporal mixing layer

WOS:000375604100003International audienceWe present a phenomenological and statistical description of the very early stages of a temporal mixing layer (TML), in which the slow fluid is R-nu = nu(high)/nu(low) times more viscous than the rapid fluid. Direct numerical simulations (DNS) are performed for two viscosity ratios, R-nu = 1 and R-nu = 9, whilst the upper and lower streams are density-matched. The space-time evolution of variable-viscosity flow (VVF) is compared with that of a baseline case, which is a constant-viscosity flow(CVF, for which R-nu = 1). The initial Reynolds number, based on the initial momentum thickness, delta(theta,) (0) is Re-theta,Re- 0 = (U-0 delta(theta 0))/nu(ref) = 160 for CVF, while it varies between 32 and 128 for VVF. It is shown that the mean velocity profile of VVF is affected by the viscosity variations, thus rectifying the myth that viscosity is a small-scale quantity that does not affect the large scales. The transport equation for mean velocity is derived and assessed through DNS data at the initial stages of the TML. The modification of the mean velocity profile is mainly due to the simultaneous occurrence of mean velocity and mean viscosity gradients

Taylor-Green vortex simulation using CABARET scheme in a weakly compressible formulation

In present paper we recall the canonical Taylor-Green vortex problem solved by in-house implementation of the novel CABARET numerical scheme in weakly compressible formulation. The simulations were carried out on the sequence of refined grids with $64^3$, $128^3$, $256^3$ cells at various Reynolds numbers corresponding to both laminar (${\rm Re}=100, 280$) and turbulent (${\rm Re}=1600, 4000$) vortex decay scenarios. The features of the numerical method are discussed in terms of the kinetic energy dissipation rate and integral enstrophy curves, temporal evolution of the spanwise vorticity, energy spectra and spatial correlation functions