ITERATED QUASI-REVERSIBILITY METHOD APPLIED TO ELLIPTIC AND PARABOLIC DATA COMPLETION PROBLEMS

International audienceWe study the iterated quasi-reversibility method to regularize ill-posed elliptic and parabolic problems: data completion problems for Poisson's and heat equations. We define an abstract setting to treat both equations at once. We demonstrate the convergence of the regularized solution to the exact one, and propose a strategy to deal with noise on the data. We present numerical experiments for both problems: a two-dimensional corrosion detection problem and the one-dimensional heat equation with lateral data. In both cases, the method prove to be efficient even with highly corrupted data

Theoretical and experimental investigation on ligands-CdS clusters interactions: Influence of solvent

International audienc

Electrical, optical and morphological properties of a new chromogenic calix[4]arene derivative

International audienceWe have studied electrical properties of ITO/azo-calix[4]arene/Al diodes by means of current voltage measurement and impedance spectroscopy in a wide frequency range. The devices with an ITO/azo-calix[4]arene/Al structure could be modeled as a simple combination of resistors and capacitors. The impedance spectra can be discussed in terms of an equivalent circuit model designed as a parallel resistor R-p and capacitor C-p network in series with resistor R-s. We extract numerical values of these parameters by fitting experimental data. Relaxation processes have been identified too from the impedance spectroscopy. Their values deduced from fitting experimental data to the model have given a dielectric relaxation time in the ms range and an exponential trap distribution

Studies on the antioxidant activity of the essential oil and extract of Tunisian Tetraclinis articulata (Vahl) Mast. (Cupressaceae)

This study analyses the chemical composition and in vitro antioxidant activity of both the essential oil and the 80% aqueous acetone extract of Tetraclinis articulata leaves. The GC-MS analysis of the essential oil identified 66 components that comprise 93.5% of the oil. The major constituents of the oil are: bornyl acetate (31.4%), α-pinène (24.5%) and camphor (20.3%). Antioxidant activities of the samples were determined using four different test systems, namely DPPH, β-carotene/linoleic acid, reducing power and metal chelating activity assay. Test results from the DPPH system showed the strongest radical scavenging activity was exhibited by the 80% aqueous acetone extract (IC(50) = 5.5 µg mL(-1)), which was two times higher than the positive control (BHT). The amount of the total phenolics, flavonoids and condensed tannins was very high in the 80% aqueous acetone extracts. The correlation between the antioxidant activity potential and total phenolic level of the extract was noted

Optical and electrical study of chromogenic calix[4]arene derivatives. Materials Science & Engineering

New chromogenic calix[4]arene derivatives proved many applications in optical and electrical fields. Organic diodes formed by sandwiching azo-calix[4]arene layers between indium-thin oxide (ITO) and (Al) contacts have been elaborated and measured. In this paper, studies of devices by current–voltage characteristics I(V) and electrical impedance spectroscopy measurements in a wide frequency range have been reported. The electrical characteristics follow a space charge limited conduction behaviour (SCLC). Therefore, the Cole–Cole plots were modelled by an equivalent circuit. Relaxation processes have been identified too from the impedance spectroscopy. The optical excitation of the organic structure revealed enhancement in electrical properties