Novel graphene electrode for retinal implants : an in vivo biocompatibility study

Altres ajuts: this work has made use of the Spanish ICTS Network MICRONANOFABS partially supported by MICINN and the ICTS 'NANBIOSIS'.Evaluating biocompatibility is a core essential step to introducing a new material as a candidate for brain-machine interfaces. Foreign body reactions often result in glial scars that can impede the performance of the interface. Having a high conductivity and large electrochemical window, graphene is a candidate material for electrical stimulation with retinal prosthesis. In this study, non-functional devices consisting of chemical vapor deposition (CVD) graphene embedded onto polyimide/SU-8 substrates were fabricated for a biocompatibility study. The devices were implanted beneath the retina of blind P23H rats. Implants were monitored by optical coherence tomography (OCT) and eye fundus which indicated a high stability in vivo up to 3 months before histology studies were done. Microglial reconstruction through confocal imaging illustrates that the presence of graphene on polyimide reduced the number of microglial cells in the retina compared to polyimide alone, thereby indicating a high biocompatibility. This study highlights an interesting approach to assess material biocompatibility in a tissue model of central nervous system, the retina, which is easily accessed optically and surgically

A Participatory Approach to Assessing the Climate-Smartness of Agricultural Interventions: The Lushoto Case

The concept of climate-smart agriculture (CSA) is gaining momentum across the globe. However, it is not specific on what should be covered under its three pillars—productivity, resilience and mitigation. Consequently, CSA encompasses many different agricultural practices/technologies, making it difficult to prioritise CSA objectives. Firstly, there is a lack of clear and workable criteria as well as methods for assessing the climate-smartness of interventions. Secondly, little information exists about the impact of the various interventions already promoted as CSA, especially in the developing world. Finally, CSA prioritisation does not take into account stakeholders’ perspectives to ensure that the interventions are applicable, suitable and of high adoption-potential. Here, we describe a new participatory protocol for assessing the climate-smartness of agricultural interventions in smallholder practices. This identifies farm-level indicators (and indices) for the food security and adaptation pillars of CSA. It also supports the participatory scoring of indicators, enabling baseline and future assessments of climate-smartness to be made. The protocol was tested among 72 farmers implementing a variety of CSA interventions in the climate-smart village of Lushoto, Tanzania. Farmers especially valued interventions that improved soil fertility and structure, reduced surface runoff, and reclaimed degraded land due to the positive impacts on yield and off-season crop agriculture. Mostly, the CSA interventions increased animal production, food production, consumption and income. The protocol is easy to adapt to different regions and farming systems and allows for the better prioritisation of interventions. But we recommend that CSA is adopted as part of a monitoring, evaluation and learning process

Chapitre 21. Rôle des cultures associées pour restaurer la productivité des sols du nord-ouest du Cameroun

Le XXIe siècle doit faire face au grand défi d’alimenter à moyen terme 9 milliards d’humains, tout en réduisant la dégradation de sols. Cette étude, basée sur des essais et des enquêtes en milieu paysan des montagnes de l’Ouest du Cameroun, explique comment les cultures associées peuvent restaurer la productivité des sols tropicaux et assurer une production soutenue supérieure de 10 à 200 % aux monocultures intensifiées, tout en réduisant l’utilisation des engrais minéraux. L’agriculture agroforestière (AF) consiste à prendre la nature comme modèle : les arbres recyclent les nutriments récupérés en profondeur et leur litière protège la surface du sol de l’agression des gouttes de pluie. Elle renforce les systèmes de cultures associées traditionnelles (3 à 47 espèces concernées) et innovantes par des techniques biophysiques pour atteindre de façon plus efficace et durable la résilience des agroécosystèmes aux effets du changement climatique et de la baisse de la ressource hydrique et nutritionnelle. En augmentant le couvert végétal et en diversifiant l’enracinement, elle exploite mieux le sol, l’eau et la lumière, produit plus de biomasse et protège mieux le sol de l’érosion, des adventices et des attaques des insectes et des maladies. Les Indices d’efficience d’équivalence (IEE) du N varient de plus de 2,5 à plus de 3,6 pour le maïs des associations bi et trispécifiques. Elle table sur les services écosystémiques fournis par ces associations plurispécifiques.The 21th century has to face big problems: how to feed 9 billions of humans and simultaneously improve the soil qualities. This study, based on trials and inquirement with the farmers of the NW Cameroon mountains, explains how mixed/intercropping can restore the tropical soil productivity and ensure a sustainable production superior (10 to 200 %) to the same pure cultures. The agroforestry tries to copy the nature: the trees recycle nutrients that their roots catch in the deep soil horizons and their litter protects efficiently the topsoil against erosion. This complex system reinforces innovative mixed peasant cropping systems by biophysical techniques to reach with the most sustainable and efficient manner the resilience of the climatic change, the water and nutritional resource falling. Developing a larger canopy and a deep rooting system mixed-cropping exploits better soil nutrients, water and light, products more biomass and protects more efficiently the soil against erosion and invaded weeds, insects and diseases. The Efficiency Equivalent Ratio of N varies about 2.5 to 3.6 for tri and bispecific associations. Mixed cropping produced security and numerous ecosystemic services