Pointwise stabilization of strings with non‐linear feedback

We consider an initial and boundary value problem for a homogenous string subject to an internal pointwise control. The solution resulting from a non‐linear feedback is studied. We give various explicit decay estimates depending on the control position and the feedback non‐linearity. Copyright © 2004 John Wiley & Sons, Ltd.     

Electrochemical determination of traces lead ions using a new nanocomposite of polypyrrole/carbon nanofibers

Journal of Solid State Electrochemistry - In this paper, a new nanocomposite of polypyrrole (PPy) and carbon nanofibers (CNFs)-modified carbon paste electrode (CPE) has been reported for the...     

Facile Synthesis of New Spirothiadiazolopyridazines by 1,3‐Dipolar Cycloaddition

New derivatives of the spiro type of pyridazines have been synthesized by 1,3‐dipolar cycloaddition of N‐aryl‐C‐ethoxycarbonylnitrile imines with pyridazin‐3(2H)‐thiones. When the nitrile oxide was used, the corresponding pyridazin‐3(2H)‐one was obtained from the intermediate spirooxathiazole by elimination of isothiocyanate group. The peri‐ and regioselectivity of the reaction were ascertained by X‐ray analysis and ¹³C NMR spectroscopy of the cycloadducts 3–9.     

Comparative Study of Surface Functionalization of Hydroxyapatite by One‐pot Grafting of Organophosphonates Species

The ability to graft apatite surface by specific ligand fields creates powerful new technology applications. Thus, grafted organophosphonate can provide an effective route to modify the surface properties of apatite materials. The ability to decorate the apatite surface with the desired functionality requires covalent attachment to solid interface; most commonly achieved using organophosphonate self‐assembly. The current study shows that various phosphonates can react with calcium ions and control the formation of the porous apatite with high surface areas as well as the porosity. The structural and surface properties are given some importance in this review.     

Retention Time of Unretained Compound Calculation and Determination of Retention Indices of Some Monosubstituted Benzenes Using a Multiparametric Method in Binary, Ternary and Quaternary Solvent RP-LC Systems

In reversed phase liquid chromatography (RP-LC), the validity of a multiparametric (MP) non-linear least-squares regression iterative method has been evaluated for 14 different aqueous mobile phases modified with one, two or three organic solvents [acetonitrile (ACN), methanol (MeOH), or tetrahydrofuran (THF)] for calculating the retention time of unretained compound t _M and the regression parameter (slope b), based on the use of alkan-2-ones and alkyl aryl ketones homologous series. The determination of t _M and b has been studied for eight binary (ACN?CH₂O or MeOH?CH₂O), 3 ternary (ACN?CMeOH?CH₂O) and 3 quaternary (ACN?CMeOH?CTHF?CH₂O) mobile phase systems on an Omnispher C₁₈ column. The multiparametric calculated t _M and b values were compared with those obtained by Guardino??s, and Grobler??s methods. The MP retention indices (RI) of ten monosubstituted benzenes with different functionality (hydroxyl, carbonyl, nitro, etc.) based on the alkan-2-ones retention index standards have been determined and compared for the different mobile phase compositions studied. The influence of organic modifier type, the nature of mobile phase system and water content on the variation of retention parameter studied in this work were discussed.     

An adaptive finite volume box scheme for solving a class of nonlinear parabolic equations

In this work we are interested in a fully nonconforming (Crouzeix–Raviart) finite element scheme for addressing a nonlinear parabolic equation. In addition to showing the equivalence with a finite volume box scheme we derive a posteriori error indicators in time and space, uncoupled as much as possible.     

On the duality problem of positive Dunford-Pettis operators on Banach lattices

We give some sufficient and necessary conditions for that a positive Dunford-Pettis operator admits a dual operator which is also Dunford-Pettis, and conversely.      

Preparation and characterization of molybdenum diselenide thin films

MoSe₂ layers, synthesized by annealing a molybdenum foil under selenium pressure, have been investigated by scanning electron microscopy, X-ray analysis, electron spectroscopy (XPS) and electrical resistance measurements. It has been found that stoichiometric layers are obtained after appropriate processing. The films crystallize in the hexagonal structure. The crystallites develop preferentially along the c axis. The binding energies deduced from the XPS lines were found to be in good agreement with those of the reference powder. The electrical resistance is governed by hopping conduction in the low temperature range (80–250 K) and by grain boundary scattering mechanisms at higher temperatures.     

Compacité des opérateurs de Dunford–Pettis positifs sur les treillis de Banach

We establish some sufficient and necessary conditions which give the compactness of positive Dunford–Pettis operators on Banach lattices. To cite this article: B. Aqzzouz et al., C. R. Acad. Sci. Paris, Ser. I 340 (2005).