The number of serological assays for SARS-CoV-2 has skyrocketed in the past year. Concerns have been raised regarding their performance characteristics, depending on the disease severity and the time of the analysis post-symptom onset (PSO). Thus, independent validations using an unbiased sample selection are required for meaningful serology data interpretation. We aimed to assess the clinical performance of six commercially available assays, the seroconversion, and the dynamics of the humoral response to SARS-CoV-2 infection. The study included 528 serum samples from 156 patients with follow-up visits up to six months PSO and 161 serum samples from healthy people. The IgG/total antibodies positive percentage increased and remained above 95% after six months when chemiluminescent immunoassay (CLIA) IgG antiS1/S2 and electro-chemiluminescent assay (ECLIA) total antiNP were used. At early time points PSO, chemiluminescent microparticle immunoassay (CMIA) IgM antiS achieved the best sensitivity. IgM and IgG appear simultaneously in most circumstances, and when performed in parallel the sensitivity increases. The severe and the moderate clinical forms were significantly associated with higher seropositivity percentage and antibody levels. High specificity was found in all evaluated assays, but the sensitivity was variable depending on the time PSO, severity of disease, detection method and targeted antigen.
The applicability and effectiveness of three novel piezoelectric coiled bender actuators to deflect a plain trailing edge flap on a straight wing in the presence of incompressible flow airloads is investigated in this paper through analytical modeling. This work builds upon previous research in which the three actuator configurations, the linear spiral type, the helicoidal type, and the hybrid type, have been proposed and analytically modeled, and the first two configurations have been experimentally validated. A simple analytical model for the piezoelectrically actuated flap is developed and used for this investigation. Results show that the use of coiled piezoelectric actuators for flap deflection is an effective approach. The variation of flap deflection angles with applied actuation voltage and wing angle of attack is also shown, together with performance envelopes.
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