An experimental investigation was performed on an LM25 aluminium alloy reinforced with silicon carbide (SiC), graphite (Gr) and moringa oleifera ash (MOA) particles. The composites with different proportions such as 5 w/% of SiC, 5 w/% of SiC + 1 w/% of Gr, 5 w/% of SiC + 3 w/% of Gr, 5 w/% SiC + 1 w/% MOA, and 5 w/% of SiC + 3 w/% of MOA were produced with the stir-casting method. The effects of the reinforcement particles on density, micro-hardness, grain size, porosity, particle distribution and microstructure were studied. A characterization study was made using optical microscopy (OP) and scanning electron microscopy (SEM). Based on the hardness and density results, the MOA-reinforced composites had better hardness and decreased porosity when compared to the Gr-reinforced composites. The MOA particles exhibited a homogeneous distribution in the matrix whereas the Gr particles had a few cluster formations.
Objective:
To determine the outcomes following various surgical and medical treatments of Coronavirus disease 2019 (COVID-19) induced acute limb ischaemia.
Methods:
A retrospective study of patients presenting with COVID induced arterial ischaemia in three hospitals from Southern India during the months of May 2020 to August 2021 was undertaken. These patients were managed by either thrombectomy, primary bypass, thrombolysis, anticoagulation or primary amputation based on the stage of ischaemia and the severity of COVID.
Results:
A total of 67 limbs in 59 patients were analysed. The average time to intervention was 15 days. Upper limb involvement was seen in 16 and lower limb in 51 limbs. Of the 67 limbs, 39 (58.2%) were treated by open surgical revascularisation, 5 (7.4%) by catheter directed lysis, 17 (25.3%) were managed conservatively and 6 (8.9%) underwent primary amputation. Successful revascularisation could be carried out in 88.6% of patients. A limb salvage rate of 80.6% was achieved in these patients with a re-intervention rate of 13.6%. Major amputation rate was 14.92% and mortality was 13.56%.
Conclusion:
Limb ischaemia after COVID can be safely managed by open thrombectomy or bypass. Similar rates of limb salvage as in non-COVID acute limb ischaemia can be obtained.
In recent years, conventional materials are rapidly replaced by advanced aluminium composites due to its lighter in weight and high-performance characteristics. These materials find vast applications in automotive components because of its excellent combination of properties such as high specific strength, high specific stiffness, better dimensional stability and enhanced wear characteristics. The present work is focused on hybrid composites manufactured by stir casting route where the A356 alloy is the matrix and SiC + Moringa Oleifera Ash (MOA) particles as reinforcements. The influence of Moringa Oleifera Ash (MOA) particles (self-lubricant) on the wear behaviour of the composites is studied. Fabricated composites are tested on a pin-on-disc test rig at dry sliding wear conditions to study the influencing input parameters such as load, sliding distance and composites. A356 Aluminium alloy is reinforced with 5% SiC as primary reinforcement, varying MOA particles with 1% and 3% as secondary reinforcement. The design of experiments (DOE) approach using Taguchi method was adopted to perform the experiments according to L9 orthogonal array and analyse the results. From Taguchi analysis, combination of best suited values is identified and reported. Inquest of influential wear test parameters and its effect on wear and friction is determined using the signal-to-noise ratio and analysis of variance (ANOVA).
This case report highlights our experience in managing two cases of acute lower limb ischemia with simultaneous acute coronary events. One patient was detected with acute ST-elevation myocardial infarction while being evaluated for acute lower limb ischemia and another patient had NSTEMI with acute left ventricular failure and delayed presentation of acute lower limb ischemia. Both had good outcomes.
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