End-of-life of a polypropylene bumper skin

The aim of this article is to show how, at PSA peugeot-citroën, Life Cycle Assessment (LCA) is used as a tool to evaluate the environmental burdens associated with a product, a process or an activity by identifying and quantifying energy, material used and wastes released to the environment. In this paper, the LCA methodology is applied to a practical case study: the comparison of various end-of-life scenarios (recycling versus incineration with or without energy recovery with landfill as a reference) for a polypropylene (PP) bumper skin. All the LCA steps (goal, inventory, impacts assessment, interpretation) are developed in this study. It is shown that in the particular case of PP, incineration with energy recovery is on an environmental point of view between 30 and 60% recycling. However, due to some uncertainties on data quality, the absolute values of the inputs/outputs for the inventory step may not be sufficient to allow strong decision making and the use of the factorial experiments (Taguchi) is then proposed to select the dominant parameters of the study. Strong environmental conclusions can then be drawn from the study.     

The ichthyosaur integument: skin fibers, a means for a strong, flexible and smooth skin

The ichthyosaur skin is examined in order to further our understanding of the adaptation of these animals to the aquatic medium and their locomotory efficiency. Softtissue structures in two excellently preserved specimens of the ichthyosaur Stenopterygius quadricissus and in a partial skull of Ichthyosaurus provide unique data on the integument of advanced or tunniform ichthyosaurs. A system of fibers of three classes based on thickness and in different levels of the integument covered almost the entire surface of the body. The thickest fibers are located deepest in the skin and the thinnest outermost. The latter consist of at least two superimposed layers of fine fibers that extend in opposing directions to form a lattice or orthogonal meshwork. The angles of these fibers vary between 25 ° and 75 ° to the long axis of the animals, depending on their location in the body. The fibers of the two other size classes, lying deeper in the tissue, were observed in single layers. The thickest fibers extend in near parallel rows approximately 60 °-80 ° to the long axis of the animal in the area near the midpoint of the body and 90 ° in the post-dorsal fin region. The intermediate-sized fibers were apparently oriented at ca. 50 °-75 ° to the animal's long axis and were regularly spaced. Of considerable interest is their attachment dorsally to longitudinal fibers. This contrasts with the general condition of helically arranged fibers in fast-swimming marine vertebrates such as tuna and sharks, but compares with the condition in sirenians. Fibers were observed in the dorsal and caudal fins but not in the limbs. The fibers in ichthyosaurs are the thickest so far noted in marine vertebrates. The presence of a complex system of fibers, which includes an orthogonal meshwork of the finest of these, suggests that creasing of the skin would have been minimized, a condition highly important in reducing drag during the locomotion of marine animals.     

Shark skin: a function in feeding

Dermal denticles are unique tooth-like structures embedded in the skin of sharks and rays that protect them from predators and ectoparasites, reduce mechanical abrasion and possibly minimize swimming-induced drag. Here, we show that juvenile lesser spotted dogfish (Scyliorhinus canicula) also use this body armour to anchor food items near their tail so that bite-sized pieces can be torn away by rapid jaw and head movements. This scale-rasp behaviour is novel among fishes and suggests a new role for skin in the feeding ecology of sharks. Scale rasping may be important ecologically because it could function to increase the dietary breadth and growth potential of juveniles.     

Malaria's deadly secret: a skin stage

The role skin plays in malaria infection has long been overlooked. Recent analysis, however, suggests skin-infecting sporozoites initiate rapid suppression of immunity, establishing early tolerance to subsequent lifecycle stages. This explains susceptibility to reinfection by mosquito bite, independent of blood stage-induced immunosuppression or semi-immunity. Vaccine trials corroborate skin-initiated immunosubversion due to skin-infecting forms, tightly correlating bite pre-exposure, live parasites in the skin and endemic vaccine failure. Rapidly advancing skin immunobiology and recently described parasite development in host skin further substantiate the proposed model, consolidating a new concept in parasite biology, exemplified by malaria: natural infection has a defined, potently immunosubversive skin stage, crucially affecting vaccine function and vitally relevant to eradication.     

Creating a blood line from human skin

A recent study has generated blood cell progenitors with therapeutic potential by direct lineage conversion of human fibroblasts, thus circumventing reprogramming to pluripotent stem cells.     

Reconstruction of a tissue-engineered skin containing melanocytes

The objective of this study was to establish a new method for reconstruction of a tissue-engineered skin containing melanocytes by employing tissue engineering. The keratinocytes, melanocytes and dermal fibroblasts were isolated and purified from human foreskin biopsies. Then the cells were used to construct a tissue-engineered skin containing melanocytes. The localization of melanocytes in the tissue-engineered skin was detected by DOPA staining, S-100 immunohistochemical staining and transmission electron microscope (TEM). The results showed that the melanocytes could be detected in the basal layer of the constructed skin and the melanocytes showed dendritic morphology. Moreover the constructed skins were used to repair the athymic mice skin defects. Animal experiment results indicated that the skin equivalents could successfully repair full thickness skin defects in athymic mice and generated black skins by 6weeks after grafting. Melanocytes located in the basal layer of the athymic mice skin could also be detected by using the S-100 immunohistochemical staining. Our established method is useful to repair the full-thickness skin defects.