23,869 research outputs found

    Crystallographic properties and elemental migration in two-stage prepared CuIn1−xAlxSe2 thin films for photovoltaic applications

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    Two-stage fabrication of CuIn1−xAlxSe2 thin films for photovoltaic absorbers using sputtered Cu–In–Al metallic precursors has been investigated. Precursors containing different relative amounts of Al were selenised and their structural and chemical properties characterised. X-ray diffraction (XRD) analyses revealed that the Al was only incorporated into the chalcopyrite structure for precursor composition ratios x = [Al]/([Al] + [In]) ⩾ 0.38, while chemical analysis of the cross-section indicated partial segregation of Al near the back of the film. Precursor films in the range of compositions that yielded no Al incorporation were then selenised at four different temperatures. Glow discharge optical emission spectroscopy, plasma profiling time-of-flight mass spectrometry and XRD analyses provided an insight into the diffusion processes and reactions taking place during the selenisation stage. The effect of post-selenisation annealing without additional Se was also investigated, and led to partial incorporation of the Al into the CuInSe2 lattice but no rediffusion

    Structural and biochemical insights of CypA and AIF interaction

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    The Cyclophilin A (CypA)/Apoptosis Inducing Factor (AIF) complex is implicated in the DNA degradation in response to various cellular stress conditions, such as oxidative stress, cerebral hypoxia-ischemia and traumatic brain injury. The pro-apoptotic form of AIF (AIF(Δ1-121)) mainly interacts with CypA through the amino acid region 370-394. The AIF(370-394) synthetic peptide inhibits complex formation in vitro by binding to CypA and exerts neuroprotection in a model of glutamate-mediated oxidative stress. Here, the binding site of AIF(Δ1-121) and AIF(370-394) on CypA has been mapped by NMR spectroscopy and biochemical studies, and a molecular model of the complex has been proposed. We show that AIF(370-394) interacts with CypA on the same surface recognized by AIF(Δ1-121) protein and that the region is very close to the CypA catalytic pocket. Such region partially overlaps with the binding site of cyclosporin A (CsA), the strongest catalytic inhibitor of CypA. Our data point toward distinct CypA structural determinants governing the inhibitor selectivity and the differential biological effects of AIF and CsA, and provide new structural insights for designing CypA/AIF selective inhibitors with therapeutic relevance in neurodegenerative diseases
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