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Abstract Pulsed electron beam deposition (PED) was used to grow indium oxide thin films on c-cut sapphire single crystalline substrates between room temperature and 500 °C under oxygen gas. A slight difference in oxygen pressure during the PED growth (from 2 × 10−2 to 1.3 × 10−2 mbar) has strong effects on the electrical and optical film properties. The indium oxide thin films grown in these conditions changed from a non-degenerate semiconducting behaviour (at 2 × 10−2 mbar) to a degenerate semiconductor one (at 1.3 × 10−2 mbar), with a metal-insulator transition at 149 K. This crossover from strong to weak localization, evidenced in the temperature dependent resistivity curves, may be due to the effects of a structural disorder in such films. The direct optical band gap was estimated from transmission spectra taking into account non-degenerate/degenerate behaviour. [ABSTRACT FROM AUTHOR]

Abstract: In this work, the pulsed electron beam deposition method (PED) is evaluated by studying the properties of ZnO thin films grown on c-cut sapphire substrates. The film composition, structure and surface morphology were investigated by means of Rutherford backscattering spectrometry, X-ray diffraction and atomic force microscopy. Optical absorption, resistivity and Hall effect measurements were performed in order to obtain the optical and electronic properties of the ZnO films. By a fine tuning of the deposition conditions, smooth, dense, stoichiometric and textured hexagonal ZnO films were epitaxially grown on (0001) sapphire at 700°C with a 30° rotation of the ZnO basal plane with respect to the sapphire substrate. The average transmittance of the films reaches 90% in the visible range with an optical band gap of 3.28eV. Electrical characterization reveals a high density of charge carrier of 3.4×1019 cm−3 along with a mobility of 11.53cm²/Vs. The electrical and optical properties are discussed and compared to ZnO thin films prepared by the similar and most well-known pulsed laser deposition method. [Copyright &y& Elsevier]

Abstract: Aged individuals with Down syndrome (DS) develop Alzheimer''s disease (AD) neuropathology by the age of 40 years. The purpose of the current study was to measure age-associated changes in APP processing in 36 individuals with DS (5 months–69 years) and in 26 controls (5 months–100 years). Alpha-secretase significantly decreased with age in DS, particularly in cases over the age of 40 years and was stable in controls. The levels of C-terminal fragments of APP reflecting alpha-secretase processing (CTF-alpha) decreased with age in both groups. In both groups, there was significant increase in beta-secretase activity with age. CTF-beta remained constant with age in controls suggesting compensatory increases in turnover/clearance mechanisms. In DS, young individuals had the lowest CTF-beta levels that may reflect rapid conversion of beta-amyloid (Aβ) to soluble pools or efficient CTF-beta clearance mechanisms. Treatments to slow or prevent AD in the general population targeting secretase activity may be more efficacious in adults with DS if combined with approaches that enhance Aβ degradation and clearance. [Copyright &y& Elsevier]

We report a wide range of electric and magneto-transport properties of epitaxial Nd-doped ZnO thin films grown on (100) MgO single crystal substrate by pulsed-laser deposition under 10−2 mbar high oxygen pressure as a function of the growth temperature T g. The classical (001) texture of the ZnO wurtzite phase is present in all films whatever the growth temperature, while for T g lower than 500 °C an additional epitaxial (100) texture is observed. These structural changes are accompanied by drastic modifications of the charge transport mechanisms. For T g = 300 °C, the films behave as a metal from 300 to 275 K, from which temperature a metal-insulator transition occurs. The electrical behaviour between 275 and 50 K is described by the quantum correction to conductivity theory in disordered systems and comforted by magneto-resistance data. For T g = 500 °C, a semiconducting behavior with partial metallic character is evidenced, while for T g = 700 °C, pure semiconductor characteristics are obtained with variable-range hopping conductivity at low temperatures. Magneto-resistance measurements indicate that Nd3+ ions act below 150 K as scattering centers for electrons only for films grown at 300 °C and 500 °C. These observations have to be related to the incorporation of Nd3+ into the ZnO films during growth. The evolution from a metallic film to a semiconducting one, while acting on the single growth temperature parameter, opens new perspective in the context of charge transport. [ABSTRACT FROM AUTHOR]

Scimitar syndrome is a variant of partial anomalous pulmonary venous return with an aberrant vein, the Scimitar vein, draining the right lung to the inferior vena cava instead of the left atrium, resulting in a left-to-right shunt. The classic frontal radiographic finding, designated as "the scimitar sign", is of a scimitar (a Turkish sword) shaped density along the right cardiac border. The diagnosis can be made by echocardiography, and cardiac catheterisation remains the gold standard to assess the left-to-right shunt. However, the place of multimodal cardiac imaging by computed tomography and magnetic resonance imaging is increasing. We report the case of a 26 year-old man presenting with chest pain during a brief panic attack, in whom scimitar syndrome was associated with a bicuspid aortic valve, a clinical association rarely reported in the literature. CT and MRI cardiac imaging was as accurate as echocardiography and hemodynamics, particularly for shunt quantification. [ABSTRACT FROM AUTHOR]