Search

International audience; Description du sujet : Le changement climatique est un obstacle majeur pour la germination et la croissance précoce des semis, tout traitement biologique qui permet d’apporter une amélioration morpho-physiologique sera d’intérêt particulier.Objectifs : Notre objectif porte sur l’évaluation des potentialités de l’extrait aqueux d’Ulva rigida en tant qu’un agent de priming, et ses capacités à booster et stimuler les graines de blé sous différentes concentrations.Méthodes : La technique de priming a été réalisée sur les graines de blé en utilisant l’algue Ulva rigida comme agent. Après préparation de l’extrait aqueux, les graines ont été amorcées à différentes concentrations à raison 0,2 ml/250 ml, 0,3 ml/250 ml, 0,5 ml/250 ml et 1 ml/250 ml. L’eau de ville a été retenue comme témoin. L’essai a été réalisé pendant 10 jours. Les taux de germination et d’inhibition, l’indice et la vitesse de germination, poids frais, poids sec, longueur des parties aérienne et racinaire et l’accumulation des polyphénols totaux ont été estimés.Résultats : Les résultats ont indiqué l’efficacité de l’extrait aqueux d’Ulva rigida en tant qu’agent de priming. À la plus faible concentration (0,2 ml/250 ml), le taux de germination, l’indice et la vitesse de germination, la croissance racinaire et aérienne, ainsi que la teneur en polyphénols totaux ont été considérablement améliorées. Sous l’effet des concentrations 0,3 ml/250 ml et 0,5 ml//250 ml, le pouvoir stimulateur a enregistré une perte d’efficacité, accompagné d’une forte accumulation des polyphénols totaux. Enfin, la forte concentration, en l’occurrence 1 ml//250 ml, a exprimé un fort taux d’inhibition.Conclusion : L’extrait aqueux de l’algue verte Ulva rigida est un agent de priming prometteur, qui peut répondre aux attentes actuelles et futures des opérateurs économiques tout en assurant la pérennité de l'activité agricole. Aux fortes concentrations, il peut servir comme inhibiteur de la germination. En revanche, aux très faibles concentrations, il stimule la semence et performe le processus de germination même dans les situations de contraintes climatiques.

Essential oil is widely used in perfumery, cosmetic, pharmaceutic and food industries. The economics of essential oil production depend on both parameters; the cultivation of aromatic herbs and the extraction of oils from these herbs. This study investigated for the first time the variation in essential oil and composition of Cytisus triflorus L'Her plant at different growth times (vegetative, flowering and fruiting stages). Essential oil was extracted by hydro-distillation. The flowering stage show the highest essential oil yield (0.61 +/- 0.02 mL/100 g) compared to those of vegetative (0.41 +/- 0.01 mL/100 g) and fruiting (0. 17 +/- 0.01 mL/100 g) stages. For all growth stages, Thirty-eight compounds were identified, representing 93.21% - 95.47% of the oil, where the main components were beta-linalool (28.28 to 38.04%), Geraniol (19.82 to 27.73%), Retinal (4.33 to 9.26%), p-Mentha-1,4-dien-8-ol (2.09 to 4.08%), gamma-Terpinene (1.27 to 4.86%) and Eugenol (2.07 to 2.28%). Monoterpene hydrocarbons were detected at higher level at flowering compared to vegetative and fruiting stages. In contrast, aldehydes were noted at higher percentage at vegetative stage. This study highlighted difference in content and composition of essential oil in Cytisus triflorus L'Her during growth stages. Flowering was the interesting stage for harvesting and with more specific composition in essential oil.

International audience; Clustering data is an important topic in acoustic emission (AE) health monitoring. Identification of damage mechanisms in composites via AE technique requires an automatic process of classification. In this work, we propose a novel and simple supervised method to discriminate AE signals produced by fracture mechanisms in polymer composites. The novelty of this work is to propose new pertinent descriptors offered by using the continuous wavelet transform, where signals of learning are decomposed and the corresponding wavelet coefficients are calculated. In addition, the entropy criterion is applied to select the most correlated wavelets associated to each failure mechanism. This process allows to establish a filter in the form of vectors for each class of signals and descriptors denote the reconstruction errors calculated by involving the filter associated to each damage mechanism. The k-means algorithm is executed to calculate the center of each class. The technique is applied to AE signals recorded from specific mechanical tests to demonstrate the performance of the proposed descriptors.

International audience; Samples of pear shoots, blossoms and leaves showing typical fire blight symptoms were collected from diseased pear trees during spring and summer over a period of 3 years from orchards situated in the Mitidja region, a main pear producing area in Northern Algeria. From all collected plant samples, thirty-seven putative Erwinia amylovora strains were isolated and identified by biochemical, serological and molecular tests. Molecular typing of these strains was performed using six variable number of tandem repeats sequences (VNTRs). Minimal spanning trees showed that four different haplotypes were present within the bacterial population analyzed. The efficacy of twenty potential bacterial antagonists was evaluated in vitro against two E. amylovora pathogenic strains. Four antagonists (Bacillus amyloliquefaciens, Bacillus methylotrophicus and two Pseudomonas brassicaceaurum) were selected to perform a biocontrol assay on immature pear fruits. Results showed that the two Pseudomonas strains were the most effective for preventive treatment on pear fruits, leading to a necrosis reduction of up to 90%. No curative effect was observed. The four selected antagonists were characterized for features linked to biocontrol activity, such as biofilm, siderophores and biosurfactant-production, motility, and effect of environmental conditions on bacterial growth.

International audience; Natural diatomite from Sig/Algeria was treated with 0.5, 1.0, 3.0 and 5.0 M nitric acid solutions for 2 h under re flux at 333 K in order to improve its performance as support of catalyst. The purified silica powders obtained from frustules can also be used to reinforce composites. The solids obtained were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FTIR) spectroscopy, thermal analyses, and nitrogen adsorption-desorption at 77 K. Treatment of diatomite earth with nitric acid reduced mineral impurities, such as Fe2O3 and alkali metal oxides (CaO, MgO), eliminated carbonates and increased SiO2 ratio from 88% to 98%. The SEM micrographs showed the original geometry of the pores to be preserved. The surface properties were also evaluated using inverse gas chromatography at infinite dilution (IGC-ID) and finite concentration (IGC-FC). The interest here was to establish whether the technique is sufficiently sensitive to detect variations in the surface properties of the diatomite due to this chemical treatment. The IGC analysis permitted to reach several surface energy components with organic probes. Between them, the distribution function of the adsorption energy sites obtained with the isopropanol probe revealed a silica structure after the 5 M nitric add treatment.

International audience; With recent advancements, micro-object contactless conveyers are becoming an essential part of the biomedical sector. They help avoid any infection and damage that can occur due to external contact. In this context, a smart micro-conveyor is devised. It is a Field Programmable Gate Array (FPGA)-based system that employs a smart surface for conveyance along with an OmniVision complementary metal-oxide-semiconductor (CMOS) HD camera for micro-object position detection and tracking. A specific FPGA-based hardware design and VHSIC (Very High Speed Integrated Circuit) Hardware Description Language (VHDL) implementation are realized. It is done without employing any Nios processor or System on a Programmable Chip (SOPC) builder based Central Processing Unit (CPU) core. It keeps the system efficient in terms of resource utilization and power consumption. The micro-object positioning status is captured with an embedded FPGA-based camera driver and it is communicated to the Image Processing, Decision Making and Command (IPDC) module. The IPDC is programmed in C++ and can run on a Personal Computer (PC) or on any appropriate embedded system. The IPDC decisions are sent back to the FPGA, which pilots the smart surface accordingly. In this way, an automated closed-loop system is employed to convey the micro-object towards a desired location. The devised system architecture and implementation principle is described. Its functionality is also verified. Results have confirmed the proper functionality of the developed system, along with its outperformance compared to other solutions.