Caractérisation agronomique d’hybrides d’olivier (Olea europaea. L) issus de croisements dirigés en Tunisie

Five olive hybrids obtained from the Tunisian variety 'Chemlali Sfax' using controlled crosses to improve the oil acidic composition. The objective of this work is to study the agronomic performance of these hybrids in an irrigated orchard (Sfax, Tunisia). The study of the acidic composition showed that 4 hybrids are characterized by an oleic acid content greater than 69% and a palmitic acid content less than 16%. The study of the agronomic parameters show that the hybrids have good performances at the level of a given character. Two hybrids have a fruit weight > 2 g, a hybrid with high productivity and vigor respectively 37.4 kg/tree and 10.6 m3, and a hybrid with reduced vigor. Thus, 4 hybrids can be proposed for registration for irrigated and intensive cultivation conditions and one hybrid is to be excluded from registration given its oil acidic composition similar to the local reference variety 'Chemlali Sfax'. Keywords: Olive, hybrids, agronomy parameters, fatty acid CompositionCinq hybrides d’olivier issus de la variété tunisienne ‘Chemlali Sfax’ ont été obtenus à partir de croisements dirigés pour améliorer la composition acidique de l'huile. L’objectif de ce travail est d’étudier le comportement agronomique de ces hybrides dans un verger conduit en irrigué (Sfax, Tunisie). L’étude de la composition acidique révèle que 4 hybrides se caractérisent par un taux en acide oléique supérieur à 69 % et un taux en acide palmitique inférieur à 16 %. L’étude des paramètres agronomiques montrent que les hybrides ont de bonnes performances au niveau d’un caractère déterminé. Deux hybrides ont un poids du fruit > 2 g, un hybride avec productivité et vigueur élevées, respectivement de 37,4 kg/arbre et 10,6 m3, et un hybride avec une vigueur réduite. De ce fait, 4 hybrides peuvent être proposés à l’inscription pour une culture irriguée et intensive et un hybride est à exclure de l’inscription vu sa composition acidique de l’huile similaire à la variété locale de référence ‘Chemlali Sfax’. Mots-clés: Olivier, hybrides, Paramètres agronomiques, Composition en acides gra

Contribution a l'etude de la reactivite en presence de l'oxygene des manganites de cuivre Cu_xMn_3_-_xO_4 (0#<=#x#<=#1) et de nickel Ni_xMn_3_-_xO_4 (0,57#<=#x#<=#1) de structure spinelle en relation avec la distribution cationique

SIGLEINIST T 73774 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Etude théorique de la réactivité radicalaire d'oléfines fluorées en télomérisation

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

The Pitzer Free Rotor Model for Nondegenerate Modes: Application to the Long-Range Behavior of Halogen Radical Reactions with Substituted Olefins

International audienceWhile the Pitzer model had been used in the past with great success for degenerate internal motions, e.g., transitional bending motions in the recombination of hydrogen and methyl radicals, simpler models are often used in the treatment of nondegenerate modes, such as the transitional bending motions in the recombination reaction of hydrogen and choloromethyl radicals. In this work, highly detailed analysis of the Pitzer free rotor treatment for nondegenerate internal motions is presented. The addition reaction of a chlorine radical with 1,1,-dichloroethylene is used here for illustrative purposes. The reaction proceeds in two steps: the reactants reach a bridged intermediate that can dissociate back to reactants or yield the *C2H2Cl3 adducts. Only the long-range part of the reaction was investigated in this paper. Electronic structure calculations were performed at the UQCISD(T)/6-31G**//UMP2/6-31G** level of theory, and canonical variational transition state theory rate constants were computed. In conclusion, it is shown that two different pathways lead to the bridged intermediate. Consideration of the forward and backward rate constants demonstrated that the more direct route to the bridged intermediate is favored kinetically

Dehydration enthalpy and dc conductivity of homoionic alkali and alkaline-earth exchanged montmorillonite with low water loadings

Dehydration heat and ionic conductivity of a series of homoionic alkali (Li+, Na+, K+, Rb+, Cs+) and alkali rare-earth (Mg2+, Ca2+, Ba2+) exchanged montmorillonite (ref. CMS: SWy-2) are investigated at low water loading. Dehydration heat is obtained via Van't Hoff's law applied to weight losses measured at several constant temperatures, i.e. treatment temperature (TT), as a function of time by thermo-gravimetric analysis . Dc conductivity is measured at various temperature using Complex Impedance Spectroscopy on samples whose the water loading is fixed by TT . Comparison with the dissociation enthalpy of alkali and alkali rare-earth cation/water complexes shows that dehydration heat montmorillonites results from the competition between opposite energy contributions due to: i) cation solvation, ii) hydration of the silicate interlayer surface and iii) structural swelling. So, depending on the balance between these various energy contributions, different behaviors are observed accordingly to the nature of the extraframework cation (EFC) with a perculiar behavior for K+. Independently on EFC, dc conductivity follows an Arrhenius behavior when the water loading is closed to zero. In contrast, this behavior is no longer observed as long as water molecules are adsorbed and, hence, in interaction with EFC. In that case, the results are well described by the empirical Vogel-Tamman-Fulcher (VTF) form, i.e. , suggesting order/disorder transition in the water/cation sub-network even at low hydration state. This outcome depends on EFC in accordance with dehydration heat. It is then shown that dc conductivity evolution with both temperature and water loading is a significant source of information regarding adsorption in connection with EFC

Non-Arrhenian Ionic dc Conductivity of Homoionic Alkali Exchanged Montmorillonites with Low Water Loadings

International audienceDc conductivity of the whole series of homoionic alkali exchanged montmorillonites is investigated by means of Complex Impedance Spectroscopy. Conductivity of the samples is measured at the dry state and at various water loadings between 0 and 6 absorbed water molecules per cation. Dc conductivity of all the dehydrated samples follows an Arrhenius behavior. In contrast, the hydrated samples exhibit a non-Arrhenius temperature dependence of dc conductivity that is fruitfully fitted by using the VTF's empirical law. It is then shown that the critical temperature, TVTF, increases with water loading until the later equals approximately 3 for the Li+ and Na+ samples and higher values for the K+, Rb+, and Cs+ samples. So, it appears that the departure from the Arrhenius behavior is directly related to the number of water molecules in interaction with the alkali extra-framework cations. For water loadings higher than 3, activation energy for dc conductivity tends to values of about 0.2−0.3 eV for all samples independently on the alkali extra-framework cations. In contrast, activation energy appears to be very sensitive to the considered alkali sample for water loadings lower than 1 and, in that case, closely related to the dehydration enthalpy of the samples