Para-infectious brain injury in COVID-19 persists at follow-up despite attenuated cytokine and autoantibody responses

To understand neurological complications of COVID-19 better both acutely and for recovery, we measured markers of brain injury, inflammatory mediators, and autoantibodies in 203 hospitalised participants; 111 with acute sera (1–11 days post-admission) and 92 convalescent sera (56 with COVID-19-associated neurological diagnoses). Here we show that compared to 60 uninfected controls, tTau, GFAP, NfL, and UCH-L1 are increased with COVID-19 infection at acute timepoints and NfL and GFAP are significantly higher in participants with neurological complications. Inflammatory mediators (IL-6, IL-12p40, HGF, M-CSF, CCL2, and IL-1RA) are associated with both altered consciousness and markers of brain injury. Autoantibodies are more common in COVID-19 than controls and some (including against MYL7, UCH-L1, and GRIN3B) are more frequent with altered consciousness. Additionally, convalescent participants with neurological complications show elevated GFAP and NfL, unrelated to attenuated systemic inflammatory mediators and to autoantibody responses. Overall, neurological complications of COVID-19 are associated with evidence of neuroglial injury in both acute and late disease and these correlate with dysregulated innate and adaptive immune responses acutely

The evolution of grain boundary character during superplastic deformation of an Al-6 pct Cu-0.4 pct Zr alloy

The evolution of microstructure, texture, and microtexture in an Al-6 pct Cu-0.4 pct Zr alloy was studied during mechanical testing at 480 °C and a strain rate of 5·10−4 s−1. The as-processed material had an elongated, banded microstructure and a deformation texture with orientation distribution along the β-orientation fiber. The true strain vs true stress curve exhibited three stages: I, II, and III. Work hardening occurred in stages I and III, whereas nearly steady-state behavior was observed in stage II. A bimodal distribution of boundary disorientation angles was evident in as-processed material and persisted into stage I, with peaks at 5–15 deg in the low-angle boundary (LAB) regime and at 45–60 deg in the high-angle boundary (HAB) regime. An increase in strain rate sensitivity coefficient, m, in stage I was accompanied by fragmentation of the initial microstructure, leading to the formation of new grains. During stage II the strain rate sensitivity coefficient, m, attained a value of 0.5, which is consistent with the onset of grain boundary sliding. In stage III, the texture and the grain boundary disorientation distribution became randomized while the m value decreased. Grain elongation and cavity formation at second-phase particles and along grain boundaries were seen in samples deformed to failure. The as-processed microstructure is described in terms of deformation banding, and a model for the evolution of such a structure during superplastic deformation is proposed.Peer reviewe