Sur la modification du PLA en vue de son application pour filet d’exclusion

RÉSUMÉ: L’agriculture contemporaine fait usage de grandes quantités de pesticides de synthèse pour contrôler les dégâts causés par les ravageurs. Bien que l’efficacité soit avérée pour permettre de nourrir une population grandissante, cette pratique entraîne de nombreux effets négatifs sur l’environnement, qui se répercutent ensuite sur les cultures et sur la biosphère, comprenant l’humain. Dans cette optique, la réduction de l’usage de composés actifs de synthèse est une voie à suivre pour permettre une production agricole pérenne sur le long terme. Pour permettre cette réduction, l’usage de méthodes innovatrices et efficaces est nécessaire dans l’industrie agricole. La technique dite d’exclusion, utilisant un filet de polymère drapé sur les cultures pour empêcher les ravageurs d’atteindre les plantes, se sont révélés efficaces et économiquement viables pour un bon nombre de cas autour du globe. Au Canada, et particulièrement au Québec, la pomme est une culture modèle de par sa sensibilité aux ravageurs ce qui entraîne un nombre d’interventions phytosanitaires élevé. Ainsi, le présent projet tend à l’amélioration de filets d’exclusion pour la protection de la pomme.----------ABSTRACT:Contemporary agriculture uses large amounts of synthetic pesticides to reduce yield losses induced by pests and pathogens. Despite these methods’ significant efficiency to feed a growing human population, they induce severe degradation of the environment, which affects the biosphere including humans. To allow a sustainable form of agriculture that maintains the quality and quantity of biodiversity, a reduction in the use of active ingredients use should be targeted. In that context, innovative and efficient methods need to be developed and implemented for industrial agriculture. Exclusion techniques, whereby a polymeric net is draped over a crop, create a physical barrier between pests and plants and have demonstrated their phytosanitary and economically beneficial outcomes. In Canada, and particularly in Québec, apples are widely grown and are a pests-sensitive crop. Therefore, the present project targets the improvement of exclusion nets to protect this culture

Use of bio-based polymers in agricultural exclusion nets: A perspective

The use of exclusion netting as an Integrated Pest Management technique is likely to become increasingly important as a means to increasing crop yields whilst minimising pesticide use. However, the increasing use of these nets will also lead to a rise in greenhouse gas emissions in the agricultural sector and pose problems related to their end-of-life disposal. Employing biopolymers made from low-carbon and renewable biomass feedstock to fabricate exclusion nets can potentially resolve these issues by merging the benefits of the two emerging technologies. Despite this, there has only been limited work on the use of biopolymer netting in agriculture. By looking at the challenges needed to be overcome for biopolymers to be widely used as a netting material, this review aims to bridge the gaps between the two fields of research. To do so, the past work done on agricultural netting is discussed, with a focus on the implemented materials and their desired properties. After this, potential candidate biopolymers for manufacturing agricultural nets are pointed out, emphasizing their sustainability with respect to widely used Life Cycle Analysis (LCA) parameters, including the end-of-life treatment

Diquat Derivatives: Highly Active, Two-Dimensional Nonlinear Optical Chromophores with Potential Redox Switchability

In this article, we present a detailed study of structure−activity relationships in diquaternized 2,2′-bipyridyl (diquat) derivatives. Sixteen new chromophores have been synthesized, with variations in the amino electron donor substituents, π-conjugated bridge, and alkyl diquaternizing unit. Our aim is to combine very large, two-dimensional (2D) quadratic nonlinear optical (NLO) responses with reversible redox chemistry. The chromophores have been characterized as their PF_6^− salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Their visible absorption spectra are dominated by intense π → π^* intramolecular charge-transfer (ICT) bands, and all show two reversible diquat-based reductions. First hyperpolarizabilities β have been measured by using hyper-Rayleigh scattering with an 800 nm laser, and Stark spectroscopy of the ICT bands affords estimated static first hyperpolarizabilities β_0. The directly and indirectly derived β values are large and increase with the extent of π-conjugation and electron donor strength. Extending the quaternizing alkyl linkage always increases the ICT energy and decreases the E_(1/2) values for diquat reduction, but a compensating increase in the ICT intensity prevents significant decreases in Stark-based β_0 responses. Nine single-crystal X-ray structures have also been obtained. Time-dependent density functional theory clarifies the molecular electronic/optical properties, and finite field calculations agree with polarized HRS data in that the NLO responses of the disubstituted species are dominated by ‘off-diagonal’ β_(zyy) components. The most significant findings of these studies are: (i) β_0 values as much as 6 times that of the chromophore in the technologically important material (E)-4′-(dimethylamino)-N-methyl-4-stilbazolium tosylate; (ii) reversible electrochemistry that offers potential for redox-switching of optical properties over multiple states; (iii) strongly 2D NLO responses that may be exploited for novel practical applications; (iv) a new polar material, suitable for bulk NLO behavior

Human prosocial preferences are related to slow-wave activity in sleep.

Prosocial behavior is crucial for the smooth functioning of society. Yet, individuals differ vastly in the propensity to behave prosocially. Here we try to explain these individual differences under normal sleep conditions without any experimental modulation of sleep. Using a portable high-density EEG we measured sleep data in 54 healthy adults (28 females) during a normal night's sleep at participants' homes. To capture prosocial preferences, participants played an incentivised public goods game in which they faced real monetary consequences. Whole-brain analyses showed that higher relative slow-wave activity (SWA, an indicator of sleep depth) in a cluster of electrodes over the right temporo-parietal junction (TPJ) was associated with increased prosocial preferences. Source localization and CSD analyses further support these findings. Recent sleep deprivation studies imply that sleeping enough makes us more prosocial; the present findings suggest that it is not only sleep duration, but particularly sufficient sleep depth in the TPJ that is positively related to prosociality. Because the TPJ plays a central role in social cognitive functions, we speculate that sleep depth in the TPJ, as reflected by relative SWA, might serve as a dispositional indicator of social cognition ability, which is reflected in prosocial preferences. These findings contribute to the emerging framework explaining the link between sleep and prosocial behavior by shedding light on the underlying mechanisms.Significance Statement Sleep deprivation reportedly hampers prosocial behavior. Yet, sleep loss is not a regular occurrence. We studied participants without experimentally manipulating their sleep and conducted polysomnography along with a prosocial economic task. We found that higher relative slow-wave activity (an indicator of sleep depth) in the right TPJ - a brain region involved in social cognition - is associated with increased prosociality. This demonstrates a novel link between deep sleep neural markers and prosocial preferences. Furthermore, our study provides evidence about a possible neural mechanism that underlies the behavioral findings of previous studies on sleep deprivation and prosocial behavior. Our findings highlight the significance of sleep quality in shaping prosociality and the potential benefits of interventions targeting sleep quality to promote social capital