A viscoelastic-viscoplastic model for a thermoplastic and sensitivity of its rheological parameters to the strain-rate

The behavior of thermoplastics depends on several factors, mainly time and temperature. The present work is the subject of an analysis of the dependence of viscoelastic viscoplastic parameters of a model of rheological behavior at the time. The material considered in this study is a polyamide 6. The model of applied behavior is represented by the Kelvin-Voigt viscoelastic mechanism mounted in series with a viscoplastic branch of Bingham. Following a mathematical formulation of the equations governing the model, tensile tests at different strain rates are conducted. The model parameters are then identified by inverse analysis. The technique of genetic algorithms has been favored. A nonlinear dependence of these parameters on the rate of strain has been observed. The dependence function has been established by a nonlinear regression technique. The comparison of the experimental results with those obtained by the model reveals a satisfactory agreement, hence the validation of the approach adopted

Antifungal Activity of Mentha Rotundifolia Essential Oil Against Fusarium Oxysporum

The antifungal activity of Mentha rotundifolia essential oil, harvested in Setif (Algeria) was evaluated in vitro against a phytopathogenic fungi Fusarium oxysporum, causing damage on tomato. The molecular identification of the strain was based on a comparison (BLAST) of the sequences obtained against a database and was often supplemented by microscopic observations. After quot%253BSANGERquot%253B sequencing of the PCR products, the sequences were received in FASTA format. Analysis of M. rotundifolia essential oil by Gas Chromatography%252FMass Spectrometry method (GC-MS) identified 14 compounds. The 3-Cyclopenten-1-one, 2-hydroxy-3- (3-methyl-2-butenyl) - was the major constituent of this oil with a rate of about 89.09%25. For this activity, we adopted the technique of direct contact on agar. F. oxysporum continued to grow on oil-free media at 1%25 and 0.1%25 (fungistatic effect)%253B also on media with an oil concentration of 0.01%25. While the explants taken from petri dish with essential oil concentration of 2%253B 4 and 10%25 did not grow (fungicidal effect). The very interesting antifungal effect of M. rotundifolia essential oil indicates the potential of this plant species as a source of natural fungicidal material. The present study revealed that this mint exhibited antifungal effect against F. oxysporum which provided a scientific basis for the use of this species as a good source of antifungal compounds. This preliminary work could provide a basis for the determination of sufficient and effective concentrations for in planta studies for the biological control of natural active substances of M. rotundifolia against fungal diseases

Respuesta del trigo duro (Triticum turgidum L. var. Durum) a la selección directa e indirecta en las condiciones semiáridas de Argelia

In arid and semi-arid areas, drought is an important abiotic factor that limits Durum wheat production. Identifying genotypes tolerant to drought is a challenge for plant breeders. This study aimed to evaluate the effect of direct and indirect selection on Durum wheat under rain-fed conditions in the high plains of Sétif, Algeria. Four parental varieties (Ofanto, MBB, Mrb5, Waha), three crosses (Ofanto/MBB, Ofanto/Mrb5, Ofanto/Waha) representing the F5, F6, and F7 populations, and one cultivar (Bousselm, control) were cultivated. Pheno-morpho-physiological traits were measured at the heading stage and yield and its components at grain maturity. Our results showed that the response to direct selection was reflected in a significant increase in grain yield, economic yield, and number of spikes, suggesting that grain yield may be improved using one of these characteristics as the selection criterion. Selection by canopy temperature was affected by a significant decrease in the drought susceptibility index (-11.3 %), making it possible to obtain abiotic stress-resistant lines. The study of the relationships between F5, F6, and F7 populations has shown that grain yield, economic yield, and plant height correlate with each generation, indicating no effect of genotype-environment interaction, unlike others. Late selection revealed eight meaningful lines (L1, L8, L14, L28, L32, L35, L36, and L40) in the selection process, maintaining high production throughout different cropping seasons. These successful lines were selected based on traits related to productivity: Gr.YLD, Ec.YLD, NS. These characters provide the same information as breeding programs, according to our results.En zonas áridas y semiáridas, la sequía es un factor abiótico que limita la producción de trigo duro; por tanto, la identificación de genotipos tolerantes a la sequía es un reto para los fitomejoradores. Este estudio buscó evaluar el efecto de la selección directa e indirecta en el trigo duro en condiciones de lluvia en las altas llanuras de Sétif, Argelia. Se cultivaron cuatro variedades parentales, tres cruces que representan las poblaciones F5, F6 y F7 y un cultivar (control). Los resultados mostraron que la respuesta a la selección directa se reflejó en un aumento significativo en el rendimiento del grano, el rendimiento económico y el número de espigas, lo que sugiere que es posible mejorar el rendimiento del grano utilizando una de estas características. La selección por temperatura del dosel se vio afectada por una disminución significativa del índice de susceptibilidad a la sequía (-11,3 %), lo que permite obtener líneas resistentes al estrés abiótico. El estudio de las relaciones entre las poblaciones F5, F6 y F7 ha mostrado que el rendimiento del grano, el rendimiento económico y la altura de la planta están correlacionados con estas generaciones, lo que indica que no se ven afectados por la interacción genotipo x ambiente, a diferencia de otros. La selección tardía reveló ocho líneas significativas, las cuales mantuvieron una alta producción en diferentes temporadas de cultivo. Estas líneas se seleccionaron con base en rasgos relacionados con la productividad que proporcionan la misma información que los programas de mejora, según nuestros resultados

Durum wheat stress tolerance induced by endophyte <i>pantoea agglomerans</i> with genes contributing to plant functions and secondary metabolite arsenal

In the arid region Bou-Sa&acirc;da at the South of Algeria, durum wheat Triticum durum L. cv Waha production is severely threatened by abiotic stresses, mainly drought and salinity. Plant growth-promoting rhizobacteria (PGPR) hold promising prospects towards sustainable and environmentally-friendly agriculture. Using habitat-adapted symbiosis strategy, the PGPR Pantoea agglomerans strain Pa was recovered from wheat roots sampled in Bou-Sa&acirc;da, conferred alleviation of salt stress in durum wheat plants and allowed considerable growth in this unhostile environment. Strain Pa showed growth up to 35 &deg;C temperature, 5&ndash;10 pH range, and up to 30% polyethylene glycol (PEG), as well as 1 M salt concentration tolerance. Pa strain displayed pertinent plant growth promotion (PGP) features (direct and indirect) such as hormone auxin biosynthesis, production of 1-aminocyclopropane-1-carboxylate (ACC) deaminase, and ammonia and phosphate solubilization. PGPR features were stable over wide salt concentrations (0&ndash;400 mM). Pa strain was also able to survive in seeds, in the non-sterile and sterile wheat rhizosphere, and was shown to have an endophytic life style. Phylogenomic analysis of strain Pa indicated that Pantoea genus suffers taxonomic imprecision which blurs species delimitation and may have impacted their practical use as biofertilizers. When applied to plants, strain Pa promoted considerable growth of wheat seedlings, high chlorophyll content, lower accumulation of proline, and favored K+ accumulation in the inoculated plants when compared to Na+ in control non-inoculated plants. Metabolomic profiling of strain Pa under one strain many compounds (OSMAC) conditions revealed a wide diversity of secondary metabolites (SM) with interesting salt stress alleviation and PGP activities. All these findings strongly promote the implementation of Pantoea agglomerans strain Pa as an efficient biofertilizer in wheat plants culture in arid and salinity-impacted regions

Study of the adaptive response of the filamentous fungus Botrytis cinerea to different metal stress

De nombreux métaux sont indispensables au métabolisme cellulaire, d’autres sont considérés toxiques même à de faibles concentrations. Différents champignons appartenant à des différents groupes taxonomiques ont été identifiés dans des milieux pollués et ont révélé une capacité à survivre et à croître en présence de concentrations potentiellement toxiques. Pour s'adapter à ce stress, les champignons ont développé plusieurs mécanismes au niveau intracellulaire et extracellulaire. En particulier, ils sont connus pour leur capacité à sécréter un large panel de protéines. Cependant, leur rôle dans l'adaptation des champignons à la toxicité des métaux n'a pas encore été étudié. Pour répondre à cette question, le champignon Botrytis cinerea a été soumis à un stress métallique en présence de cuivre, zinc, nickel ou cadmium, les protéines sécrétées ont été collectées et séparées par 2D-PAGE. Deux métabolites ont également été analysés, l'acide oxalique et la nicotianamine. Enfin, les capacités de biosorption des champignons isolés à partir de sols pollués ont été étudiées. L'analyse du sécrétome a révélé 116 spots dont le volume varie en réponse d'au moins un métal. Cinquante-cinq de ces spots sont associés à des protéines uniques. La classification fonctionnelle de ces protéines a révélé que la production d'oxydoréductases et des enzymes dégradant la paroi cellulaire a été modifié en réponse aux métaux. L’étude de la production d'acide oxalique par Botrytis cinerea en réponse aux métaux montre une induction de la sécrétion d'oxalate en réponse au Zn et une accumulation de la nicotianamine, métabolite intracellulaire capable de fixer les métaux chez les plantes. Le gène de la nicotianamine synthase, est d’ailleurs surexprimé en présence de Cu, Zn et Ni. Plusieurs espèces fongiques ont été isolées à partir de sols pollués par des métaux, parmi ceux-ci Trichoderma asperellum et Zygorrhynchus moelleri montrent les meilleurs capacités de biosorption (10mg de Cu/g de matière sèche) des ions CuMetal ions are essential elements in many cellular processes. However, metal excess becomes toxic and constitutes a global environmental hazard. A range of fungi from all major taxonomic groups were found in metal-polluted habitats and the ability to survive and grow in the presence of potentially toxic concentrations is frequently encountered. To adapt to this stress, fungi have evolved several mechanisms at both intracellular and extracellular levels. In particular, fungi are well known for their ability to secrete a large panel of proteins. However, their role in the adaptation of fungi to metal toxicity has not yet been investigated. To address this question, here, the fungus Botrytis cinerea was challenged to copper, zinc, nickel or cadmium stress and secreted proteins were collected and separated by 2D-PAGE. Two metabolites were also analyzed, oxalic acid and nicotianamine. Finally, biosorption capacities of fungi isolated from polluted soils were investigated. Secretome analysis revealed one hundred and sixteen spots whose volume varied in at least one tested condition were observed on 2D gels. Fifty-five of these spots were associated with unique proteins and functional classification revealed that the production of oxidoreductases and cell-wall degrading enzymes was modified in response to metals. Study of oxalic acid and nicotianamine (NA) production by Botrytis cinerea in response to tested metals reveal that Zn induces oxalate secretion and that NA synthase gene is upregulated in presence of Cu, Zn and Ni. Many fungal species were isolated from metal polluted soils among them Trichoderma asperellum and Zygorrhynchus moelleri which show the maximum biosorption capacities of Cu ion

Monitoring Biological Modes in a Bioreactor Process by Computer Simulation

This paper deals with the general framework of fermentation system modeling and monitoring, focusing on the fermentation of Escherichia coli. Our main objective is to develop an algorithm for the online detection of acetate production during the culture of recombinant proteins. The analysis the fermentation process shows that it behaves like a hybrid dynamic system with commutation (since it can be represented by 5 nonlinear models). We present a strategy of fault detection based on residual generation for detecting the different actual biological modes. The residual generation is based on nonlinear analytical redundancy relations. The simulation results show that the several modes that are occulted during the bacteria cultivation can be detected by residuals using a nonlinear dynamic model and a reduced instrumentation

Simulation of model analysis of fed batch fermented process.

International audienc

A Neural Adaptive Assisted Backstepping Controller for MPPT in Photovoltaic Applications

Maximum power point tracking is a key asset to ensure an efficient energy conversion when a photovoltaic power source is involved. In this work, a novel approach combining a Neural-Network based tracking technique with an highly efficient algorithm for non-inverting buck-boost DC-DC converter (NIBB) control is proposed. The approach is validated through comparison against the well-known PO algorithm, resulting superior both in terms of identifying the correct operating point for the PV device, and in terms of dynamic stability of the converter

Virtual Sensors to Drive Anaerobic Digestion under a Synergetic Controller

International audienceA robust synergetic controller using different observers is developed to drive an anaerobic digestion biogas plant. The latter, a highly nonlinear process requires prohibitive cost sensors. Furthermore, some variables are downright immeasurable rendering control an intricate challenge. Only biogas flow which can be effectively measured, due to an easily integrated low cost sensor, will be considered available and used in this work. The proposed synergetic controller depends on immeasurable system states, thus observers will be used for state estimation. Substrate and biomass concentrations required in the synergetic control law will be obtained via three virtual sensors developed for a one stage fermentation process model. The model, used in this paper, consider the mechanization phase responsible for the biogas production because the objective is to improve the amount of methane produced. A simulation study of the biogas plant control with the proposed technique is compared to a classic PID (Proportional, Integral and Derivative) approach. Comparative studies are provided for observation and control via computer simulations