On the behaviour of nanoparticles in oil-in-water emulsions with different surfactants

The distribution of narrowly dispersed gold nanoparticles in hexane-in-water emulsions was studied for different surfactants. Good surfactants such as SDS and Triton X-100 block the oil-water interfaces and confine particles in the droplet. Other surfactants (Tween 85 and Span 20) form synergistic mixtures with the nanoparticles at the interfaces that lower the surface tension more than any component. Supraparticles with fully defined particle distribution form in the droplets only for surfactants that block the interface. Other surfactants promote the formation of fcc agglomerates. Nanoparticles in emulsions behave markedly different from microparticles-their structure formation is governed by free energy minimization, while microparticles are dominated by kinetics

Smoothing the H0H_0 tension with a dynamical dark energy model

The discrepancy between Planck data and direct measurements of the current expansion rate $H_0$ and the matter fluctuation amplitude $S_8$ has become one of the most intriguing puzzles in cosmology nowadays. The $H_0$ tension has reached $4.2\sigma$ in the context of standard cosmology i.e $\Lambda$CDM. Therefore, explanations to this issue are mandatory to unveil its secrets. Despite its success, $\Lambda$CDM is unable to give a satisfying explanation to the tension problem. Unless some systematic errors might be hidden in the observable measurements, physics beyond the standard model of cosmology must be advocated. In this perspective, we study a phantom dynamical dark energy model as an alternative to $\Lambda$CDM in order to explain the aforementioned issues. This phantom model is characterised by one extra parameter, $\Omega_{pdde}$, compared to $\Lambda$CDM. We obtain a strong positive correlation between $H_0$ and $\Omega_{pdde}$, for all data combinations. Using Planck measurements together with BAO and Pantheon, we find that the $H_0$ and the $S_8$ tensions are $3\sigma$ and $2.6\sigma$, respectively. By introducing a prior on the absolute magnitude, $M_B$, of the SN Ia, the $H_0$ tension decreases to $2.27\sigma$ with $H_0 = 69.76_{-0.82}^{+0.75}$ km s$^{-1}$ Mpc$^{-1}$ and the $S_8$ tension reaches the value $2.37\sigma$ with $S_8 =0.8269_{-0.012}^{+0.011}$.Comment: 11 pages, 4 figure

Composites en matières premières renouvelables et leurs procédés

National audienceThe development of new bio-based composites and efficient manufacturing methods that are suitable for series processing is the purpose of the current sub-project C4 of the Excellence Cluster MERGE, sponsored by DFG (Deutsche Forschungsgemeinschaft). Two different types of materials are combined: bio-based thermoplastic biopolymers such as bio-polyethylene (BioPE) or bio-polyamides (BioPA) and renewable reinforcing materials such as thin wood veneer or unidirectional flax fibers. To achieve a high-efficiency in terms of mass-production, reproducibility and flexibility, it is required to overlap several steps in the realization of semi-finished and final products. The improvement of the adhesion at the interface of the components, the implementation of continuous processes in order to increase energetically the yielding and the final design, through several methods, for the future potential applications are so many perspectives to achieve. MOTS-CLÉS : polymère bio-basé thermoplastique; renforcement naturel (Lin ou placage en bois) ; Amélioration de l'adhésion à l'interface matrice/renforcement ; Procédés plastic/textile continu ; Application dans l'automobile et équipement sportifsLe développement de matériaux bio-basés et de méthodes efficaces de mise en forme, adaptable à la production en série, est le but de l'actuel sous-projet C4 du programme d'excellence MERGE financé par la DFG (Deutsche Forschungsgemeinschaft). Ainsi, deux types de matériaux sont combinés : Des polymères bio-ressourcés thermoplastiques tels que bio-polyéthylène (BioPE) ou bio-polyamide (BioPA) et des matériaux de renforcements renouvelables tels que le placage en bois ou des fibres de lin unidirectionnelles continues. Pour atteindre un haut rendement en termes de production en masse, de reproductibilité et de flexibilité, il est requis de suivre plusieurs étapes dans la réalisation de produits semi-finis et finis. L'amélioration de l'adhésion à l'interface des composantes, la mise en place de procédés continus afin d'augmenter leur rendement, et la mise en forme finale, par diverses méthodes, pour des futures potentiels applications sont autant d'objectifs à atteindre

Comparative study between direct steam generation and molten salt solar tower plants in the climatic conditions of the eastern Moroccan region

International audienceThis study deals with a numerical investigation to assess and compare the thermal and economic performance of two solar tower power systems. It concerns the Molten Salt (MS) and Direct Steam Generation (DSG) technologies used as heat carrier and storage. For this purpose, a 50 MWe solar tower plant without thermal energy storage under the climatic conditions of the eastern Moroccan region is simulated with the System Advisor Model (SAM) software. The meteorological data has been collected via a high precision meteorological station located in Oujda city(34°40'53'' N 1°54'30.9'' W). The results are presented in terms of monthly energy production, annual energy output, and Levelized Electricity Cost (LEC). From these findings, it can be concluded that, for an amount annual Direct Normal Irradiance (DNI) of 1989.9 kWh/m2/yr, the molten salt plant has the highest annual energy production than the DSG (86.3 GWh for MS against 83.3 GWh for DSG) and the LEC of the Molten salt plant is 12.5 % lower than the DSG plant. ©2020. CBIORE-IJRED. All rights reserve