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Background: Cortical hand strokes affect the 'hand knob' of the motor cortex, resulting in isolated distal upper limb or hand weakness. They are rare and can be easily misdiagnosed for peripheral lesions.Case Reports: Case 1: A 59-year-old man presented to the Emergency Department (ED) after noticing left hand weakness while driving. There was no sensory deficit noted. A full neurological examination suggested an upper motor neurone rather than a peripheral nerve lesion. This was confirmed by a magnetic resonance imaging scan of his brain. Case 2: An 88-year-old man presented to the ED after developing sudden-onset left hand weakness while completing a newspaper puzzle. Power returned gradually over approximately 4 h, with no sensory symptoms being noted. A transient ischemic attack leading to cortical hand was diagnosed. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Cortical hand strokes are a rare, but important, differential for wrist drop. They are often first strokes and embolic in nature. Therefore, correct diagnosis is vital to enable initiation of secondary prevention. [ABSTRACT FROM AUTHOR]

Abstract Photovoltaics (PV) are increasingly important for electrification in rural Sub-Saharan Africa, but what is the best battery technology to use? To explore this question, a small-scale domestic PV system for South Africa (20-year lifetime) to deliver 1.42 kWh electricity from batteries overnight with 10-h discharge was costed with various Li-ion, Pb-acid and Aquion aqueous hybrid ion batteries (AHIBs). Environmental impact; compatibility with circular economy; potential for cost-reduction through lifetime extension; and valorisation of batteries at end-of-life is discussed. Batteries are 81–93% of system costs, and battery production required over the system lifetime would emit 743, 674 and 6060 kg CO2-eq (Pb-acid, Li-ion and AHIBs respectively). Hazardous materials in Li-ion and Pb-acid batteries pose risks at end-of-life. Li-ion and AHIBs face potential resource supply constraints due to use of Co, Li and graphite. Closed-loop recycling and refurbishment of Pb-acid batteries is well established in South Africa. Currently, no African facilities for Li-ion or AHIB recycling exist, with little opportunity to retain material value from these batteries within the region. Despite lower efficiencies and shorter lifetimes, Pb-acid batteries, which are readily available from domestic manufacturing at low cost, are the current best choice for sustainable small-scale domestic PV systems in South Africa. [ABSTRACT FROM AUTHOR]

We present a controlled, stepwise formation of methylammonium bismuth iodide (CH 3 NH 3 ) 3 Bi 2 I 9 perovskite films prepared via the vapour assisted solution process (VASP) by exposing BiI 3 films to CH 3 NH 3 I (MAI) vapours for different reaction times, (CH 3 NH 3 ) 3 Bi 2 I 9 semiconductor films with tunable optoelectronic properties are obtained. Solar cells prepared on mesoporous TiO 2 substrates yielded hysteresis-free efficiencies upto 3.17% with good reproducibility. The good performance is attributed mainly to the homogeneous surface coverage, improved stoichiometry, reduced metallic content in the bulk, and desired optoelectronic properties of the absorbing material. In addition, solar cells prepared using pure BiI 3 films without MAI exposure achieved a power conversion efficiency of 0.34%. The non-encapsulated (CH 3 NH 3 ) 3 Bi 2 I 9 devices were found to be stable for as long as 60 days with only 0.1% drop in efficiency. This controlled formation of (CH 3 NH 3 ) 3 Bi 2 I 9 perovskite films highlights the benefit of the VASP technique to optimize material stoichiometry, morphology, solar cell performance, and long-term durability. [ABSTRACT FROM AUTHOR]

In this study, we report the experimental and numerical investigation of the behaviour of a spontaneously oscillatory reaction in a fed-batch reactor (FBR). We use a cerium catalysed BZ model with a modified Oregonator mechanism. In fed-batch mode, we observe phase-locked, quasiperiodic and period-doubling responses, depending on the amplitude and period of the replacement cycle. A series of single pulse experiments is used to construct phase transition curves, from which limit point (Arnold tongues) and period-doubling bifurcation boundaries can be constructed. Experimental boundaries are compared with boundaries determined numerically using a path following analysis. The results are used to determine the variation, in terms of the mean rate of production of the oxidised catalyst, with the operating conditions of the FBR for a fixed residence time. [Copyright &y& Elsevier]