Synthesis and Characterization of Glomerate GaN Nanowires

Glomerate GaN nanowires were synthesized on Si(111) substrates by annealing sputtered Ga2O3/Co films under flowing ammonia at temperature of 950 °C. X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy and Fourier transformed infrared spectra were used to characterize the morphology, crystallinity and microstructure of the as-synthesized samples. Our results show that the samples are of hexagonal wurtzite structure. For the majority of GaN nanowires, the length is up to tens of microns and the diameter is in the range of 50–200 nm. The growth process of the GaN nanowires is dominated by Co–Ga–N alloy mechanism

Late Cretaceous chronostratigraphy (Turonian–Maastrichtian): SK1 core Songliao Basin, China

Non-marine ostracodes, charophytes and palynomorphs are abundant in most Cretaceous lacustrine basins of East Asia. However, their ranges are not directly integrated with marine biota that defines the Cretaceous stages. Non-biotic events such as magnetochrons and radiometric ages in these terrestrial deposits enable their correlation with marine strata. The SK1 north and south composited cores in the Songliao Basin present a continuous section of Upper Cretaceous non-marine fossil and magnetochron successions in superposed order. These chronostratigraphic events are integrated with marine events by an X/Y graphic plot between the core data and a global database of Global Section and Stratotype Points (GSSP) and key reference sections. This plot projects stage boundaries in marine sections into the SK1 section and interpolates numerical ages to the first and last occurrences of biota and to lithostratigraphic boundaries. This stratigraphic experiment tests and refines age calibrations based on both manual interpolation of depths to numerical ages and cyclostratigraphy. Ages derived by interpolation are similar and ages by cyclostratigraphy are older because stage boundaries are calibrated to a different age scale

The onset of widespread marine red beds and the evolution of ferruginous oceans

The evolution of oceanic redox state in the past is poorly known. Here, the authors present a temporal record of banded iron formations and marine red beds, which indicate deep-ocean oxygenation occurred in the middle Ediacaran, coinciding with the onset of widespread marine red beds