Today, fresh water resources are reached by pollution, in particular the organic pollutants. Recent studies reveal the presence of various toxic substances, such as pesticides and textile colorants, in surface or underground waters everywhere in the world. Among these products, we are interested in two pesticides, the paraquat (PQ) and diquat (DQ) as well as a textile colorant: methylene blue (BM). The treatment of these pollutants requires in addition to the usual treatments (coagulation-flocculation, decantation, filtration, oxidation…), a stage of refining by adsorption on activated carbon. These processes remain hard and expensive. In this respect, this actual work depends on the elimination of the PQ, the DQ and the BM, by adsorption on natural polymeric chitin, which is a principal structural constituent of the protective cuticles shellfish, insects and also of the cellular walls of certain mushrooms and micro-organisms. This material is chosen because of on one hand its great abundance in Morocco, and on the other hand, its structural and textural properties, allowing its use in the treatment of polluted water. Chitin were extracted primarily from Moroccan exoskeleton shellfish. Characterization of chitin was performed by infrared spectroscopy and nuclear magnetic resonance. The adsorption of PQ, DQ and BM by chitin was studied at different pH values, the pollutants-adsorbent contact time and initial pollutants concentration. The adsorption is described by both Langmuir-type isotherm and Freundlich-type isotherm.

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“Assist as needed” control algorithms promote activity of patients during robotic gait training. Implementing these requires a free walking mode of a device, as unassisted motions should not be hindered. The goal of this study was to assess the normality of walking in the free walking mode of the LOPES gait trainer, an 8 degrees-of-freedom lightweight impedance controlledexoskeleton. Kinematics, gait parameters and muscle activity of walking in a free walking mode in the device were compared with those of walking freely on a treadmill. Average values and variability of the spatio-temporal gait variables showed no or small (relative to cycle-to-cycle variability) changes and the kinematics showed a significant and relevant decrease in knee angle range only. Muscles involved in push off showed a small decrease, whereas muscles involved in acceleration and deceleration of the swing leg showed an increase of their activity. Timing of the activity was mainly unaffected. Most of the observed differences could be ascribed to the inertia of the exoskeleton. Overall, walking with the LOPES resembled free walking, although this required several adaptations in muscle activity. These adaptations are such that we expect that Assist as Needed training can be implemented in LOPES.

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