Traditional epoxy resin systems have long been used for vacuum impregnation of large electro-magnets. However, the mechanical strength of these systems is disappointingly low when operated at temperatures above about 7O0C where the failure mechanism is more often by adhesion at the copper interface than by cohesion within the resin. A range of resin systems based on cyanate ester are currently being developed by CTD Inc. which are suitable for vncuum impregnation and may offer advantages over the epoxy resin systems. In order to BSSESS the thermo-mechanical performance of these newly developed materials a programme of testing and evaluation of the basic cyanate ester resin (CTD 403) has been carried out and the results are presented here. I INTRODUCTIONThe first stage of the testing programme involved manufacturing and testing lap shear test specimens at various temperatures to compare the strength of glass-reinforced cyanate ester with that of glass-reinforced epoxy resin. These results proved very encouraging so a series of mechanical strength tests was carried out on pure cyanate ester (CE) and epoxy resin to determine and compare their mechanical properties including their fiacture toughness and glass transition temperatures. A series of large torsion and tension test samples formed fiom glass reinforced cyanate ester resin discs, were then tested at room temperature and 10D°C. These provided shear strength with and without compression and tensile strength data on test specimens which do not contain the high stress concentrations produced in the lap shear specimens. Finally a reduced series of tests was carried out on pure cyanate ester resin samples formed using different curing temperatures to investigate the effect of cure temperature on the mechanical properties. I1 DESIGN, MANUFACTURE AND TESTING OF LAPSHEAR TEST SPECIMENS The simple lap shear test specimen geometry was chosen as it has been previously used by many Laboratories and companies [1,2] for testing epoxy resin systems providing an extensive data base for comparisons, and is also relatively easy to manufacture and test. A cross section showing the specimen geometry is shown in fig. 1.The copper plates were machined from half hard silver bearing copper (DIN 17666), which is commonly used for the manufacture of large copper coils.The main stages in the preparation of the specimens was:i) Grit blast and clean surfaces to give a mechanical key ii) Coat with a CE primer and cure primer. iii) Lay 52 glass cIoth layers between the copper plates and assemble into an impregnation fixture. iv) Dry the assembly in a vacuum oven. v) Vacuum impregnate with CE resin at room temperature. vi) Gel and then cure the resin at 1 3 5 T for 4 hours, .o Fig. I . Lap Shear Test SpecimenA total of 15 lap shear test specimens were manufactured and were tested using the lnstron 1195 testing machine at the Culham Science Centre. The lap-shear test specimens were supported in a stainiess steel "U' shaped holder before being compressed between chromium plated steel platens....
The purpose of this work was to review and synthesise the evidence on the comparative effectiveness of neutralising monoclonal antibody (nMAB) therapies in individuals exposed to or infected with SARS-CoV-2 and at high risk of developing severe COVID-19. Outcomes of interest were mortality, healthcare utilisation, and safety. A rapid systematic review was undertaken to identify and synthesise relevant RCT evidence using a Bayesian Network Meta-Analysis. Relative treatment effects for individual nMABs (compared with placebo and one another) were estimated. Pooled effects for the nMAB class compared with placebo were estimated. Relative effects were combined with baseline natural history models to predict the expected risk reductions per 1000 patients treated. Eight articles investigating four nMABs (bamlanivimab, bamlanivimab/etesevimab, casirivimab/imdevimab, sotrovimab) were identified. All four therapies were associated with a statistically significant reduction in hospitalisation (70–80% reduction in relative risk; absolute reduction of 35–40 hospitalisations per 1000 patients). For mortality, ICU admission, and invasive ventilation, the risk was lower for all nMABs compared with placebo with moderate to high uncertainty due to small event numbers. Rates of serious AEs and infusion reactions were comparable between nMABs and placebo. Pairwise comparisons between nMABs were typically uncertain, with broadly comparable efficacy. In conclusion, nMABs are effective at reducing hospitalisation among infected individuals at high-risk of severe COVID-19, and are likely to reduce mortality, ICU admission, and invasive ventilation rates; the effect on these latter outcomes is more uncertain. Widespread vaccination and the emergence of nMAB-resistant variants make the generalisability of these results to current patient populations difficult.
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