Système et procédé de fabrication d'un produit composite à base de particules cellulosiques à défibrer et d'un liant thermoplastique

L’invention propose un procédé de fabrication d'un produit composite à base de particules cellulosiques à défibrer (21) et d’un liant thermoplastique (22), au moyen d'une machine d'extrusion (10) comprenant deux vis (11) parallèles engrenant l'une dans l'autre et entraînées en rotation à l'intérieur d'un fourreau allongé (12), chaque vis étant constituée d’un arbre central et d’une pluralité d’éléments de vis (15) présentant chacun un type, une longueur et un pas de vis déterminés. Selon l’invention les particules cellulosiques à défibrer et le liant thermoplastique sont à l’état solide à l’entrée, de sorte qu’on réalise, à l'intérieur du fourreau (12) en un seul passage, un défibrage des particules cellulosiques à défibrer (21), une fonte du liant thermoplastique (22) et un mélange intime des particules cellulosiques défibrées obtenues avec le liant thermoplastique fondu et un agent de plastification (40) pour obtenir un produit composite extrudable (60)

Heavy metals in marine mammals

peer reviewe

Biological oceanography and marine food webs: role of marine mammals and seabirds

peer reviewe

Tuna and dolphin associations in the Northeast Atlantic: Evidence of different ecological niches from stable isotope and heavy metal measurements

Associations of tunas and dolphins in the wild are quite frequent events and the question arises how predators requiring similar diet in the same habitat share their environmental resources. As isotopic composition of an animal is related to that of its preys, stable isotopes (13C/12C and 15N/14N) analyses were performed in three predator species from the Northeast Atlantic: the striped dolphin, Stenella coeruleoalba, the common dolphin Delphinus delphis, and the albacore tuna, Thunnus alalunga, and compared to their previously described stomach content. Heavy metals (Cd, Zn, Cu and Fe) are mainly transferred through the diet and so, have been determined in the tissues of the animals. Tunas muscles display higher delta15N than in common and striped dolphins (mean: 11.4 0/00 vs. 10.3 0/00 and 10.4 0/00, respectively) which reflects its higher trophic level nutrition. Higher delta13C are found in common (-18.4 0/00) and striped dolphin (-18.10/00) muscles than in albacore tuna (-19.3 0/00) likely in relation with its migratory pattern. The most striking feature is the presence of two levels of cadmium concentrations in the livers of the tunas (32 mg kg-1 dry weight vs. 5 mg kg-1 dry weight). These two groups also differ by their iron concentrations and their delta15N and delta 13C liver values. These results suggest that in the Biscay Bay, tunas occupy two different ecological niches likely based on different squid input in their diet

Metallothioneins in Marine Mammals

Metallothioneins (MTs) have been detected in livers and kidneys of 10 marine mammals species (Pinnipeds and Odontocetes). Characterization of renal MTs of striped dolphin has shown that the protein has two isoforms (MT-1 and MT-2) with a molecular weight estimated around 6,800. MT concentrations also vary widely in marine mammals tissues (from 58 to 1,200 microg x g(-1) ww) underlying the numerous parameters involved: physiological status, pregnancy, age, diet. The participation of this protein in metal detoxification has been investigated since high levels of cadmium (Cd) and mercury (Hg) have been measured in livers and kidneys of marine mammals. It has been suggested that those animals can mitigate at least in part, the toxic effects of Cd and Hg through binding to MTs. The percentage of the cytosolic Cd bound to MTs can reach almost 100%. On the contrary, the percentage of hepatic and renal Hg bound to MT is very low (generally less than 10%) and this metal is mainly associated with selenium (HgSe) under a detoxified form in the insoluble fraction of the tissues. MTs appear to play a minor role in the binding and detoxification of Hg by marine mammals. On the contrary, close and dynamic interactions occur between Cd and MTs. Cytosolic MTs appear as a potential short term way of detoxification of Cd accumulated from diet. Long-term detoxification would imply a sequestration of the metal under a precipitated form (e.g. in lysosomes)

Carte géologique de Wallonie au 1/25.000: feuille de Rebecq-Ittre n°39/1-2 et livret-guide

info:eu-repo/semantics/publishe

Notice explicative de la carte géologique Rebecq-Ittre: Carte géologique de Wallonie Echelle: 1/25 000

info:eu-repo/semantics/published

Carte géologique de Wallonie au 1/25.000: feuille de Rebecq-Ittre n°39/1-2

info:eu-repo/semantics/published