Preparation and analysis by UV-Vis of zinc phthalocyanine complexes

We have prepared and isolated a series of zinc phthalocyanine complexes (ZnPc, ZnPcF8, biZnPc, F12biZnPc). These compounds have been analyzed by electronic spectrometry. The analysis of results demonstrates that the importance of intramolecular interactions in the binuclear species depends on the nature of the peripheral substituents.     

Determination of the phase transitions in BaTiO3 type crystals by using the theory of symmetry breaking: Etude des transitions de phase dans les cristaux du type BaTiO3 par la theorie des symetries brisees

Crystaks of the BaTiO₃ family showing the following sequence of phase transitions : tetragonal, orthorhombic, rhombohedral, are investigated. From the MASON-MATHIAS model based on a TiO₆ octahedron in which a Ti ion can be displaced along the different pseudo-cubic axes, these different polar structures are found by considering the possible lowering of the O_h symmetry associated with the non polar phase. By the appropriate orientation of the basis of the vector representation connected with the occurence of the polarisation $\text{P}$, the order-parameter of the phase transitions are determined for three cases (O_h → C_4v, C_2v, C_3v). The order of the transition is discussed. These parameters can be used for a thermodynamical investigation of the crystal based on an expansion of its free energy.     

Search for electron neutrino appearance at the Delta m2 approximately 1 eV2 scale

The MiniBooNE Collaboration reports first results of a search for nu e appearance in a nu mu beam. With two largely independent analyses, we observe no significant excess of events above the background for reconstructed neutrino energies above 475 MeV. The data are consistent with no oscillations within a two-neutrino appearance-only oscillation model.     

Lysosomes Are Sites of Fluoroquinolone Photosensitization in Human Skin Fibroblasts: A Microspectrofluorometric Approach*

The fluoroquinolone antibiotics are widely used despite their strong phototoxicity under solar UV irradiation. Although they are known as good photodynamic photosensitizers, other factors than production of activated oxygen species may play a role in the effectiveness of the phototoxic effect. Subcellular localization is one of the important parameters that may determine this strength. Using microspectrofluorometry, it is shown that norfloxacin, ofloxacin, lomefloxacin, ciproflaxin and BAYy3118 are readily incorporated into lysosomes of HS68 human skin fibroblasts although weak staining of the whole cytoplasm also occurs especially with norfloxacin. Consistent with their photoinstability in solutions, the fluoroquinolones under study are readily photobleached by UVA in the HS68 fibroblasts. The BAYy3118 derivative that has the fastest bleaching rate also shows the strongest phototoxicity toward HS68 fibroblasts. Photosensitization with these fluoroquinolones induces lysosomal membrane damage as shown by the increased rate of leakage of the lysosomal probe lucifer yellow as compared to that observed with untreated cells.     

Strong solutions for a 1D viscous bilayer shallow water model

In this paper, we consider a viscous bilayer shallow water model in one space dimension that represents two superposed immiscible fluids. For this model, we prove the existence of strong solutions in a periodic domain. The initial heights are required to be bounded above and below away from zero and we get the same bounds for every time. Our analysis is based on the construction of approximate systems which satisfy the BD entropy and on the method developed by A. Mellet and A. Vasseur to obtain the existence of global strong solutions for the one dimensional Navier–Stokes equations.     

Sensitive determination of diuron on zinc oxide nanoparticles modified carbon paste electrode in soil and water samples

An electrochemical sensor based on Zinc oxide nanoparticles (ZnONPs) modified carbon paste electrode was designed for the toxic diuron pesticide detection. The ZnONPs were synthesized through the hydrothermal route and their structural properties were investigated via scanning electron microscopy (SEM) and X-ray diffraction powder (XRD). The designed ZnONPs-modified carbon paste electrode (ZnONPs-CPE) was characterized using cyclic voltammetry and electrochemical impedance spectroscopy. The sensor showed significantly enhanced sensitivity on the diuron oxidation peak current, compared to the bare carbon paste electrode. Qualitative and quantitative analysis were performed using cyclic voltammetry (CV) and square wave voltammetry (SWV). Experimental parameters such as pH, amount of ZnONPs and frequency were evaluated and the optimized conditions were obtained with 0.1 M phosphate buffer solution at pH=8, a frequency of 50 Hz and a quantity of 5 mg of ZnONPs. Under these conditions, linear responses ranging from 1.3 to 7.7 μM and 8.6 to 30 μM of diuron were obtained, with correlation coefficients of R²=0.994 and 0.996 respectively. Detection and quantification limits of 0.22 μM and 0.84 μM (S/N=3) were respectively achieved based on the 3σ method. The interference of some ions on the oxidation peak of diuron on ZnONPs-CPE was also evaluated and no interference was observed, therefore demonstrating the selectivity of the sensor. The proposed sensor, designed with ecofriendly materials, is sensitive, selective and was effectively used for diuron determination in soils and water samples with recoveries ranging from 98 % to 101.5 %.