Mesures prédictives dans le modèle de Cox–Dirichlet à censures aléatoiresPredictive measures in the Cox–Dirichlet model with random censures

This paper is devoted to the extension to randomly censored observations of the study of predictive measures in the nonparametric bayesian Cox–Dirichlet model, which has been developed for non censored observations by N. Gouget and J.P. Raoult in [3]. We show that in all cases, the predictive measures stay piecewise regular (as defined in [3]). This implies that there exists a partition of the space of observations in subsets, included in linear subspaces, such that in each of them the predictive measure is absolutely continuous w.r.t. the Lebesgue measure. We compute the so defined densities for right censoring. To cite this article: F. Messaci, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 557–560.     

Influence de la structure sur l'hydrolyse des N-pyrrolylmethylene-2 anilines

Hydrolysis of the imine function of a series of Schiff bases derived from pyrrole-2-carboxaldehyde and substituted anilines (X = H, p-OCH₃, p-OC₂H₅, p-CH₃, p-Cl, p-Br, m-CN, m-NO₂, p-NO₂) was studied in all of the pH ranges. The hydrolysis curves log k_abs (mn^?1) = f(pH) were established in buffered aqueous methanol by polarography or amperometry. The shapes of the curves obtained for pH > 5 indicates that N-pyrrolylmethylene-2 anilines hydrolyse according to the same mechanism as N-benzylidene anilines. The particular stability of these products for pH < 5 permits one to obtain complete hydrolysis curves in acid media. A very good Hammett correlation (k_obs = + 1,73) has been established from the maxima which appear for strong acidity. This stability is interpreted as due to the specific electron-donating effect of the pyrrole nucleus. The influence of the structural parameter X on the morphology of the curves log k_abs = f(pH) and on the hydrolysis mechanism of the imine function is discussed in all of the pH ranges.     

Extraction of Cobalt(II) from Sulfate Medium with Substituted Salicylideneanilines

Russian Journal of Physical Chemistry A - The liquid-liquid extraction of cobalt(II) from sulfate media (Na2SO4) with substituted salicylideneanilines (SAN) is investigated. The stoichiometry of...     

SYNTHÉSE DE THIOÉTHERS D'ACIDES PROPYLBORONIQUES S - BENZYLÉS

The protection of the hydroxy group of p-cresol 1 by o-silylation gives derivatives 2 and 3 , the methyl group of which can be brominated by NBS. The phase transfer catalysis applied to 4 and 5 is a good way which permits the mild introduction of the allylthio group ( 6 and 7 ). Hydroboration applied to silylated compounds 8 and 9 , followed by methanolysis and hydrolysis leads to target acids 10 and 11 in a good yield.

La protection du groupement hydroxy du p-crésol 1 par o-silylation donne les dérivés 2 et 3 ce qui permet de bromer le substituant méthyle par le N-bromosuccinimide (NBS). La catalyse par transfert de phase (CTP) appliquée aux produits 4 et 5 est une bonne méthode pour introduire un groupement allylthio (composés 6 , 7 ). L'hydroboration des composés silylés 8 et 9 , suivie d'une méthanolyse et d'une hydrolyse permet d'accéder aux acides cibles 10 et 11 avec de bons rendements.     

Investigation of 7-((dioctylamino)methyl)quinoline-8-ol for uptake and removal of uranyl ions

A new 8-hydroxyquinoline derivative extractant was synthesized via the Mannich reaction from a secondary amine. Various analytical techniques (¹H, ¹³C NMR, FTIR, mass spectroscopy) were used to characterize our product. The use of this new extractant for the uptake and removal of uranyl ions in aqueous solution was investigated. Conditions for an effective sorption were optimized with respect to different experimental parameters in batch process. The results showed that the extraction rate increases for solutions with a pH in the range [0.65–1.13]. The total sorption capacity was 105 (mg g^?1) under optimum experimental conditions. The extraction of UO₂ ²⁺ was found to be quantitative (100 %) at initial uranyl concentration less than or equal to 41.59 mg/L. Thermodynamic parameters showed the adsorption of an endothermic process and a spontaneous nature, respectively.     

Screening, Gene Sequencing and Characterising of Lipase for Methanolysis of Crude Palm Oil

Staphylococcus sp. WL1 lipase (LipFWS) was investigated for methanolysis of crude palm oil (CPO) at moderate temperatures. Experiments were conducted in the following order: searching for the suitable bacterium for producing lipase from activated sludge, sequencing lipase gene, identifying lipase activity, then synthesising CPO biodiesel using the enzyme. From bacterial screening, one isolated specimen which consistently showed the highest extracellular lipase activity was identified as Staphylococcus sp. WL1 possessing lipFWS (lipase gene of 2,244 bp). The LipFWS deduced was a protein of 747 amino acid residues containing an α/β hydrolase core domain with predicted triad catalytic residues to be Ser474, His704 and Asp665. Optimal conditions for the LipFWS activity were found to be at 55 °C and pH 7.0 (in phosphate buffer but not in Tris buffer). The lipase had a K _M of 0.75 mM and a V _max of 0.33 mM?min^?1 on p-nitrophenyl palmitate substrate. The lyophilised crude LipFWS performed as good as the commonly used catalyst potassium hydroxide for methanolysis of CPO. ESI-IT-MS spectra indicated that the CPO was converted into biodiesel, suggesting that free LipFWS is a worthy alternative for CPO biodiesel synthesis.     

Solvability of a Mixed Nonlocal Problem for a Nonlinear Singular Viscoelastic Equation

The present paper deals with a nonlinear viscoelastic equation having a dissipation term. With the equation some classical and non classical boundary conditions are combined. Based on some a priori bounds, iteration processes and density arguments, we simultaneously solve the nonlinear and the associated linear problems.     

Efficient <Emphasis Type="Italic">Candida rugosa</Emphasis> lipase immobilization on Maghnite clay and application for the production of (<Emphasis Type="Italic">1R</Emphasis>)-(−)-Menthyl acetate

This work focused on the identification of natural, economical, and efficient supports for immobilization of Candida rugosa lipase (CRL) to catalyze the resolution of (±)-menthol. To this purpose, CRL has been immobilized on natural montmorillonite from Algeria (Maghnite-H), ion-exchange resins (Amberjet^®1200-H and Amberjet^®4200-Cl), and diatomaceous earth (Celite^®545). After a preliminary screening of supports, the immobilization of CRL led to a markedly improved enantioselectivity. Excellent enantioselectivity (E ≥ 134) was achieved by the four supported lipases (E = 68 for free enzyme). Compared to the three other supports tested, higher enantioselectivity was observed with Maghnite-H used as immobilization matrix. In this work, the effects of solvent, reaction time, and temperature, on the conversion as well as on enantioselectivity were investigated. The maximum of conversion (% C = 43%) with high enantiomeric excess of products (eep > 99) was obtained when the reaction is catalyzed by CRL immobilized on Maghnite-H at 30 °C for 24 h, and using toluene as selected solvent. Immobilized CRL on Maghnite-H exhibited good thermostability over a wide temperature range (30–90 °C) compared to the free one. These results suggest that CRL immobilized on Maghnite-H has good potential as biocatalyst for the production of (1R)-(?)-menthyl acetate.     

On the higher dimension Boussinesq equation with nonclassical condition

This paper deals with the solvability and uniqueness of a higher dimension mixed nonlocal problem for a Boussinesq equation. Galerkin's method was the main used tool for proving the solvability of the given nonlocal problem. Copyright © 2010 John Wiley & Sons, Ltd.