Search

Genetic hemochromatosis and alpha1-antitrypsin (AAT) deficiency are frequent in white populations. Conflicting data on the association of the two conditions and on the severity of the disease in those in whom these disorders coexist have emerged from analyses of small numbers of patients. To determine if the frequency of AAT deficiency is increased in genetic hemochromatosis, we characterized this protein by isoelectric focusing and DNA analysis in 115 Italian patients with the disease and 290 controls. The frequency of AAT deficiency in patients with genetic hemochromatosis was similar to that in controls (10% and 9%, respectively). The prevalence of cirrhosis in patients with genetic hemochromatosis with MM phenotype was 53%, compared with 58% in those with non-MM phenotype; that of hepatocellular carcinoma, occurring only in cirrhotic patients, was 22% and 28%, respectively. In conclusion, the frequency of AAT deficiency was not increased in our large series of Italian patients with genetic hemochromatosis. Patients in whom the two defects coexisted did not appear to have a more severe disease, but the limited number of subjects with non-MM phenotype does not allow a conclusive evaluation of clinical differences between them and patients with genetic hemochromatosis with MM phenotype.

Solution-free and catalyst-free vertically aligned ZnO nanorods have been synthesized by thermal CVD reactor at relatively low temperature (

International audience; We investigate the high-temperature magnetic and transport properties of LaMn7O12, which displays a similar perovskitelike structure and the same single-valent Mn3+ properties of LaMnO3 but a much simpler Jahn-Teller JT distortion at TJT=650 K. We find that the magnetic response of LaMn7O12 is similar to that of LaMnO3 below TJT, but strikingly different in the undistorted phase above TJT, where the Curie-Weiss susceptibility is strongly suppressed. Electrical resistivity and thermopower measurements unveil a concomitant crossover from nonadiabatic to adiabatic small polaron regime. This suggests that the above suppression is due to low-spin electron-hole dimers formed by the eg charge transfer between Mn sites and stabilized by the slow JT dynamics above TJT.

We report the synthesis and the characterization of PrMn7O12, a new manganite with multiple (quadruple) perovskite structure of general chemical formula: AA13B4O12. This family of manganites is extremely interesting and is attracting a great attention; thanks to its structural peculiarity (and complexity), it might help the comprehension of the ordering phenomena (charge, orbital, spin), which is one of the most challenging issues in the strongly electron correlated rare-earth oxides. Like the majority of the materials having similar structure, PrMn7O12 is a metastable compound, requiring high pressure synthesis. Contrary to other reported isostructural compounds, PrMn7O12 crystallizes in two different forms with rhombohedral (R-3) and monoclinic (I2/m) symmetry, the latter characterized by a distortion of the perovskite structure lattice that depends on the synthesis conditions. The approximate stability fields of the two PrMn7O12 phases have been defined in the P/T space, allowing the synthesis of almost single phase samples functional to physical characterization. For the monoclinic phase we succeeded in the growth of crystals sufficiently large to perform structural refinement by single crystal x-ray diffraction data; the rhombohedral structure was instead refined by Rietveld method applied to powder x-ray diffraction data. Although the two phases differ slightly from the crystallographic point of view, physical characterizations reveal surprisingly different properties, in particular for what concerns the magnetic behavior. The differences of the two structures might be explained with a different electronic configuration of Mn, implying the partial occupation of Mn3+ in low spin state on the B site of the rhombohedral polymorph.

In this work, we report on the structural analyses of undoped CdTe samples grown by the vapor phase and the Bridgman methods. Different techniques were used for determining the structural defects: wet etching, high resolution X-ray diffraction, double crystal X-ray topography and monochromatic SEM-cathodoluminescence mapping. The density and the nature of the structural defects were found to be correlated to the stoichiometry of the samples, as determined by a detailed analysis of the temperature dependence of the partial pressure of the vapors in equilibrium with the solid.