Purification and characterization of an agglutinin from the hemolymph of Locusta migratoria (Orthoptera)

International audienc

Insect haemolymph : cooperation between humoral and cellular factors in Locusta migratoria

36 ref.International audienc

Mise en evidence et etude ultrastructurale de procaryotes de type rickettsien dans les glandes salivaires des Triatomidae (Heteroptera)

National audienc

Ultrastructural study of surface components of Xenorhabdus sp. in different cell phases and culture conditions

International audienc

Isolation of Multiple Subspecies of Bacillus thuringiensis from a Population of the European Sunflower Moth, Homoeosoma nebulella

Five subspecies of Bacillus thuringiensis were isolated from dead and diseased larvae obtained from a laboratory colony of the European sunflower moth, Homoeosoma nebulella. The subspecies isolated were B. thuringiensis subspp. thuringiensis (H 1a), kurstaki (H 3a3b3c), aizawai (H 7), morrisoni (H 8a8b), and thompsoni (H 12). Most isolates produced typical bipyramidal crystals, but the B. thuringiensis subsp. thuringiensis isolate produced spherical crystals and the B. thuringiensis subsp. thompsoni isolate produced a pyramidal crystal. Analysis of the parasporal crystals by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the crystals from the B. thuringiensis subsp. kurstaki and aizawai isolates contained a protein of 138 kDa whereas those from B. thuringiensis subsp. morrisoni contained a protein of 145 kDa. The crystals from B. thuringiensis subsp. thuringiensis contained proteins of 125, 128, and 138 kDa, whereas those from B. thuringiensis subsp. thompsoni were the most unusual, containing proteins of 37 and 42 kDa. Bioassays of purified crystals conducted against second-instar larvae of H. nebulella showed that the isolates of B. thuringiensis subspp. aizawai, kurstaki, and thuringiensis were the most toxic, with 50% lethal concentrations (LC(inf50)s) of 0.15, 0.17, and 0.26 (mu)g/ml, respectively. The isolates of B. thuringiensis subspp. morrisoni and thompsoni had LC(inf50)s of 2.62 and 37.5 (mu)g/ml, respectively. These results show that a single insect species can simultaneously host and be affected by a variety of subspecies of B. thuringiensis producing different insecticidal proteins

Study of the dry reforming of methane and ethanol using Rh catalysts supported on doped alumina

International audienceAbstractVarious MxOy-Al2O3 oxides (M =Zr, Mg, Ni, Ce, La), prepared by a sol-gel method, were used as supports for rhodium catalysts in methane and ethanol dry reforming. After calcination, the Rh/MxOy-Al2O3 catalysts present BET surface areas between 85 and 208 m(2) g(-1). For the CH4 dry reforming, the highest yields in hydrogen are obtained in the following ranking: Rh/NiO-Al2O3 > Rh/Al2O3 > Rh/MgO-Al2O3 approximate to Rh/CeO2-Al2O3 > Rh/ZrO2-Al2O3 > Rh/La2O3-Al2O3, not very different from the one for ethanol dry reforming at 800 degrees C which is: Rh/NiO-Al2O3 >> Rh/Al2O3 Rh/MgO-Al2O3 approximate to Rh/CeO2-Al2O3 > Rh/ZrO2-Al2O3 approximate to Rh/La2O3-Al2O3, although the reaction temperature is different. For the two reactions, the best catalyst is Rh/NiO-Al2O3 even if it deactivates during the reaction due to carbon deposition. This high activity may be explained by both the presence of the NiAl2O4 spinel phase, avoiding the deactivation of rhodium by migration in alumina, and the high dispersion of Rh favored by the presence of nickel particles at the support surface. Moreover, Ni particles on the support surface also contribute to the activity as demonstrated by the high hydrogen yield obtained in the presence of NiO-Al2O3, which is similar to the one obtained with Rh/Al2O

Toward new benchmark adsorbents:preparation and characterization of activated carbon from argan nut shell for bisphenol A removal

Abstract The use of argan nut shell as a precursor for producing activated carbon was investigated in this work. Two activated carbons AC-HP and AC-Na were prepared from argan nut shell by chemical activation method using phosphoric acid (H₃PO₄) and sodium hydroxide (NaOH), respectively. Textural, morphological, and surface chemistry characteristics were studied by nitrogen physisorption, TGA, SEM, TXRF, FTIR, XRD, and by determining the pHPZC of the AC-HP. The adsorption experiments revealed that AC-HP was more efficient in adsorption of BPA due to high specific surface area (1372 m²/g) compared to AC-Na (798 m²/g). The obtained adsorption data of BPA on AC-HP correlated well with the pseudo-second-order model and the Langmuir isotherm (Qmax = 1250 mg/g at 293 K). The thermodynamic parameters (ΔG° < 0, ΔH° < 0, and ΔS° < 0) indicate that adsorption of BPA on AC-HP was spontaneous and exothermic in nature. The regeneration of AC-HP showed excellent results after 5 cycles (95–93%). This work does not only provide a potential way to use argan nut shell but also represents a sustainable approach to synthesize AC-HP, which might be an ideal material for various applications (energy storage, catalysis, and environmental remediation)

Total oxidation of dichloromethane over silica modified alumina catalysts washcoated on ceramic monoliths

Abstract Silica modified alumina was used in this study for coating of a cordierite monolith substrate with two different channel densities. The performance of the prepared monolith catalysts was evaluated in catalytic total oxidation of dichloromethane before and after Pt impregnation. The characteristics similar to the powder form catalysts were kept rather successfully after washcoating the monolith as evidenced by electron microscopy (FESEM) and N2 physisorption. A dichloromethane (DCM) conversion of higher than 80% at 500 °C was reached over all the catalysts with 200 cpsi. The maximum conversion was obtained with the catalyst containing 10 mol % of silica. The total amount of major byproducts (CO, CH3Cl and CH2O) were slightly decreased by increasing the silica loading, and remarkably after Pt impregnation. After impregnation of Pt, the HCl yields were increased for two samples with the higher loading of silica (10 and 15 mol %) and reached the maximum when silica loading was 10%. Even though Pt impregnation did not significantly affect the DCM conversion, it improved the selectivity. Comparison between the two substrates (200 and 600 cpsi) evidenced that the key parameters of the monolith influencing the DCM oxidation are low value of open fraction area, hydraulic diameter, thermal integrity factor and high value of mechanical integrity factor and geometric surface area