Electron transfer in quantum-dot-sensitized ZnO nanowires: ultrafast time-resolved absorption and terahertz study

Photoinduced electron injection dynamics from CdSe quantum dots to ZnO nanowires is studied by transient absorption and time-resolved terahertz spectroscopy measurements. Ultrafast electron transfer from the CdSe quantum dots to ZnO is proven to be efficient already on a picoseconds time scale (τ = 3-12 ps). The measured kinetics was found to have a two-component character, whose origin is discussed in detail. The obtained results suggest that electrons are injected into ZnO via an intermediate charge transfer state.     

Equivariant functions and integrals of elliptic functions

In this paper, we introduce the theory of equivariant functions by studying their analytic, geometric and algebraic properties. We also determine the necessary and sufficient conditions under which an equivariant form arises from modular forms. This study was motivated by observing examples of functions for which the Schwarzian derivative is a modular form on a discrete group. We also investigate the Fourier expansions of normalized equivariant functions, and a strong emphasis is made on the connections to elliptic functions and their integrals.     

Projection iterative method for solving general variational inequalities

In this paper, we suggest and analyze a new projection iterative method for solving general variational inequalities by using a new step size. We also prove the global convergence of the proposed method under some suitable conditions. Some preliminary numerical experiments are included to illustrate the advantage and efficiency of the proposed method.     

Antibacterial and antioxidant potency of floral honeys from different botanical and geographical origins

In order to assess their physicochemical and antioxidant properties as well as their antimicrobial potency, four varieties of honey from different botanical and geographical origins were used. The agar incorporation method was used to determine the antimicrobial potency of honeys. The total phenol content was determined by a modified Folin-Ciocalteu method and the free radical scavenging activity by the Fe³⁺ reducing power (FRAP) assay. Manuka honey was the most effective against Staphylococcus aureus Oxa R and S. aureus Oxa S with a Minimum Inhibitory Concentration (MIC) of 6% and 7%, respectively, whereas wild carrot honey was the most effective against Pseudomonas aeruginosa, with a MIC of 12%. Lavender honey was the least effective against all tested strains, even though was found to have the lowest pH and water content. Manuka honey had the highest content of polyphenols, with 899.09 ± 11.75 mg gallic acid/kg, whereas lavender honey had the lowest, with 111.42 ± 3.54 mg gallic acid/kg. A very significant correlation (r value was 0.9079 at P < 0.05) was observed between the total polyphenolic content and the Fe²⁺ content formed in the presence of the honey antioxidants. The differences between honey samples in terms of antibacterial and antioxidant activity could be attributed to the natural variations in floral sources of nectar and the different locations.     

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.     

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.     

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.     

Low thrombogenicity coating of nonwoven PET fiber structures for vascular grafts

Vascular PET grafts (Dacron) have shown good performance in large vessels (≥6 mm) applications. To address the urgent unmet need for small‐diameter (2–6 mm) vascular grafts, proprietary high‐compliance nonwoven PET fiber structures were modified with various PEG concentrations using PVA as a cross‐linking agent, to fabricate non‐thrombogenic mechanically compliant vascular grafts. The blood compatibility assays measured through platelet adhesion (SEM and mepacrine dye) and platelet activation (morphological changes, P‐selectin secretion, and TXB2 production) demonstrate that functionalization using a 10% PEG solution was sufficient to significantly reduce platelet adhesion/activation close to optimal literature‐reported levels observed on carbon‐coated ePTFE.

     

Resistivity and thermoelectric power of molten aluminium: experiment and theory

The electrical resistivity?ρ?of metallic liquid aluminium is measured as a function of temperature. The measurement needs an experimental design able to get the resistivity of a very reactive liquid metal. Liquid aluminium seems to be a simple metal. We first interpret the experimental results by using an ab initio calculation of the electrical resistivity ρ(E) as function of the electron energy, taking into account recent exchange and correlation contributions in the framework of the generalized gradient approximation (GGA). But surprisingly the classical theoretical interpretation leads to an apparent inconsistency. Thus we discuss the sensitivity of the calculation on the inputs and propose improvements of the theoretical approach. They allow a better physical understanding of pure liquid aluminium which is absolutely necessary before undertaking the study of liquid aluminium alloys.