A facile method for the preparation of bifunctional Mn:ZnS/ZnS/Fe3O4 magnetic and fluorescent nanocrystals

Bifunctional magnetic and fluorescent core/shell/shell Mn:ZnS/ZnS/Fe3O4 nanocrystals were synthesized in a basic aqueous solution using 3-mercaptopropionic acid (MPA) as a capping ligand. The structural and optical properties of the heterostructures were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscopy (TEM), UV–vis spectroscopy and photoluminescence (PL) spectroscopy. The PL spectra of Mn:ZnS/ZnS/Fe3O4 quantum dots (QDs) showed marked visible emission around 584 nm related to the 4T1 → 6A1 Mn2+ transition. The PL quantum yield (QY) and the remnant magnetization can be regulated by varying the thickness of the magnetic shell. The results showed that an increase in the thickness of the Fe3O4 magnetite layer around the Mn:ZnS/ZnS core reduced the PL QY but improved the magnetic properties of the composites. Nevertheless, a good compromise was achieved in order to maintain the dual modality of the nanocrystals, which may be promising candidates for various biological applications

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

Structure of Na2Ca(HPO4)2 determined ab initio from conventional powder diffraction data

ABSTRACT. — The structure of Na 2Ca(HPO 4) 2 is monoclinic (space group P2 1, Z = 2) with cell parameters a = 9.0652(3) Å, b = 7.1468(2) Å, c = 5.4700(2) Å and β = 98.782(1)°. The initial structural model was obtained from direct methods applied to 650 integrated intensities. The Rietveld refinement converged to final Bragg and profiles indicators R B = 4.1 % and R P = 8.6 %. The tridimensional structure is built up from interconnected [CaO 7] pentagonal bipyramids, [NaO 5] distorted trigonal bipyramids and [HPO 4] tetrahedra sharing corners or edges. Sodium atoms occupy tunnels extending along the c axis with non-regular octogonal aperture

Etude des arcs électriques à l'ouverture et de la résistance de contact pour des contacts AgNi dans leurs appareillages.

National audienc

First report of eumycetoma of the hand in Tunisia

International audienceEumycetoma is a chronic, necrotizing infection of fungal origin that usually occurs on a lower extremity, especially the foot. We describe the first case in Tunisia of eumycetoma of the hand due to Pseudallescheria boydii. Case report. - A 48-year-old agricultural worker presented with a swelling and painless cutaneous nodules of the right hand and wrist that drained spontaneously. No trauma of the hand was noted. Examination of the hand revealed multiple crusted sinus tracts in the palm and on the back of the hand. The right hand appeared swollen and deformed. There was no adenopathy or fever. Radiographic examination showed bone involvement with destruction of the wrist bones. The diagnosis of eumycetoma was confirmed by histological evidence (stained sections) that showed granules containing fungal hyphae and positive culture for P boydii. Initially, treatment with ketoconazole (400 mg daily for 14 months) failed. The patient subsequently received itraconazole (400 mg daily for 18 months) and a marked improvement was obtained. Six years after treatment was stopped, there had been no recurrence, but bone involvement resulted in permanent deformity with wrist ankylosis. (C) 2010 Elsevier Masson SAS. All rights reserved