Study of corrosion-erosion behaviour of stainless alloys in industrial phosphoric acid medium

The corrosion and corrosion-abrasion resistance of some stainless steels in industrial phosphoric acid 30% P₂O₅ has been studied using electrochemical techniques. The corrosion rate of materials increases with the increase of temperature. Alloys which contain chromium, molybdenum and nitrogen in sufficient quantities present the best behaviour.In the abrasion-corrosion conditions, the experimental device set up allowed to follow continually samples electrochemical behaviour. Under dynamic conditions and without solid particles, the increase of acid projection speed has no effect on the alloys corrosion behaviour. The adding of abrasive leads to a general increase of corrosion rate and to a decrease of material resistance. Under these conditions, materials attack is controlled by synergistic effect between the abrasion and the impurities. The cast 30% Cr shows good resistance according to his high chromium content.     

New Anti-Leukemic Effect of Carvacrol and Thymol Combination through Synergistic Induction of Different Cell Death Pathways

Acute myeloid leukemia (AML) is a cancer of the myeloid lineage of blood cells, and treatment for AML is lengthy and can be very expensive. Medicinal plants and their bioactive molecules are potential candidates for improving human health. In this work, we studied the effect of Ptychotis verticillata (PV) essential oil and its derivatives, carvacrol and thymol, in AML cell lines. We demonstrated that a combination of carvacrol and thymol induced tumor cell death with low toxicity on normal cells. Mechanistically, we highlighted that different molecular pathways, including apoptosis, oxidative, reticular stress, autophagy, and necrosis, are implicated in this potential synergistic effect. Using quantitative RT-PCR, Western blotting, and apoptosis inhibitors, we showed that cell death induced by the carvacrol and thymol combination is caspase-dependent in the HL60 cell line and caspase-independent in the other cell lines tested. Further investigations should focus on improving the manufacturing of these compounds and understanding their anti-tumoral mechanisms of action. These efforts will lead to an increase in the efficiency of the oncotherapy strategy regarding AML.     

Alternating Direction Method for Maximum Entropy Subject to Simple Constraint Sets

The problem of maximizing the entropy subject to simple constraint sets is reformulated as a structured variational inequality problem by introducing dual variables. A new iterative alternating direction method is then developed that generates alternatively the dual and primal iterates. For some existing maximum entropy problems in the literature, the new dual iterate can be derived from a simple projection and then the new primal iterate can be obtained via solving approximately n separate one-dimensional strong monotone equations. Therefore, the proposed method is very easy to carry out. Preliminary numerical results show that the method is applicable.     

Constrained stabilization: an enlargement technique of positively invariant sets

This paper presents a new technique of enlargement of positivelyinvariant sets for linear systems with input saturation. Thistechnique is based on the use of the convex hull of the unionof N preconstructed positively invariant sets. It is shown thatthe obtained region is a stability region where the controlis always admissible.     

Quantum Screening Operators and Canonical q-de Rham Cocycles

In this paper a close connection is established between certain cohomology spaces of representations of the quantum affine algebra , and a twisted $q$-de Rham (Jackson–Aomoto) cohomology of configuration spaces using the quantum screening operators. Received: 24 December 1997 / Accepted: 2 April 1998     

Extended LQP Method for Monotone Nonlinear Complementarity Problems

To solve nonlinear complementarity problems (NCP), the logarithmic-quadratic proximal (LQP) method solves a system of nonlinear equations at each iteration. In this paper, the iterates generated by the original LQP method are extended by explicit formulas and thus an extended LQP method is presented. It is proved theoretically that the lower bound of the progress obtained by the extended LQP method is greater than that by the original LQP method. Preliminary numerical results are provided to verify the theoretical assertions and the effectiveness of both the original and the extended LQP method.     

Hypersurfaces d'un fibré vectoriel Riemannien à courbure de Gauss prescriteHypersurfaces of a Riemannian vector bundle with prescribed Gaussian curvature

Let M be a compact Riemannian manifold, E a Riemannian vector bundle on M and Σ the sphere subbundle of E. We look for embeddings of Σ into E admitting prescribed Gaussian curvatures of various types. To cite this article: A. Hanani, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 927–930.     

Surface analysis for catalyst layer (PT/PTFE/C) and diffusion layer (PTFE/C) for proton exchange membrane fuel cells systems (PEMFCs)

X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) studies have been used to analyze the surface of diffusion layer (PTFE/C) and catalyst layer (Pt/C/PTFE) of electrode. Detail analysis of carbon C_1s peak showed that the carbon was of the form of C, C-O, CO, CF, CF₂ and CF₃ with CF₂ is more dominated on the surface compared to CF and CF₃. The oxygen O_1s photoelectron peak showed that the oxygen was of the form of CO and C-O. The platinum was of the form of Pt⁰ with some Pt oxidized to PtO. The scanning electron microscopy was used to observe the dispersion of Teflon in the diffusion layer, the distribution of platinum in the catalyst layer loaded with 0.38 mg Pt/cm² and also the cross section of the membrane electrode assembly. The prepared electrode delivers a superior performance compared with the commercial electrode (E-TEK). The difference in performance between the two electrodes is due to the good localization of the platinum particles.     

Sous-groupes canoniques et cycles évanescents <Emphasis Type="Italic">p</Emphasis>-adiques pour les variétés abéliennes

Sans résumé     

The Characterisation of the Regularity of the Jacobian Determinant in the Framework of Potential Spaces

We give necessary and sufficient conditions on the parameterss₁, s₂, ..., s_m, p₁, p₂, ..., p_m such that the Jacobian determinantextends to a bounded operator from into Z'. Here all spaces are defined on Rⁿ and 2mn. In almostall cases the regularity of the Jacobian determinant is calculatedexactly.