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Africa is the only habitable continent that is not yet host to a light source - an important tool across disciplines. Scientists from the Executive Committee of the African Light Source Foundation discuss work towards building an advanced light source in Africa, and what remains to be done.
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The electrochemical performance of hydrothermal synthesized three dimensional (3D) orthorhombic vanadium pentoxide (V2O5) nanosheets and vanadium pentoxide/graphene foam (V2O5/GF) composites at different mass loading of GF were successfully studied. The optimized V2O5/GF-150â¯mg composite provided a high specific capacity of 73â¯mAâ¯hâ¯g-1, which was much higher than that the pristine V2O5 (60â¯mAâ¯hâ¯g-1) nanosheets at a specific current of 1â¯Aâ¯g-1. A hybrid capacitor was also fabricated by adopting a carbon-based negative electrode obtained from the pyrolysis of an iron-PANI polymer (C-Fe/PANI) mixture and the 3D V2O5/GF-150â¯mg composite as the positive electrode in 6â¯M KOH electrolyte. The hybrid device of V2O5/GF-150â¯mg//C-Fe/PANI demonstrated a high energy density of 39â¯Wâ¯hâ¯kg-1 with a corresponding high power density of 947â¯Wâ¯kg-1 at a specific current of 1 A g-1 in an operating voltage window of 0.0-1.6â¯V. The hybrid device also exhibited an excellent cycling stability with 74% capacity retention recorded for up to 10,000 constant charging-discharge cycles and an excellent ageing test at a specific current of 10â¯Aâ¯g-1.
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This work presents the results for identification of chemical phases obtained by several laboratories as a part of an international nuclear forensic round-robin exercise. In this work powder X-ray diffraction (p-XRD) is regarded as the reference technique. Neutron diffraction produced a superior high-angle diffraction pattern relative to p-XRD. Requiring only small amounts of sample, µ-Raman spectroscopy was used for the first time in this context as a potentially complementary technique to p-XRD. The chemical phases were identified as pure UO2 in two materials, and as a mixture of UO2, U3O8 and an intermediate species U3O7 in the third material.