Background: The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) results in a cluster of coronavirus disease 2019 (COVID-19). We reported the clinical characteristics of COVID-19 patients with acute respiratory distress syndrome (ARDS), and further investigated the treatment and progression of ARDS in COVID-19. Methods: This study enrolled 109 patients with COVID-19 admitted to the Central Hospital of Wuhan, a designated hospital in Wuhan, China, from January 2 to February 1, 2020. Patients were followed up to February 12, 2020. The clinical data were collected from the electronic medical records. The differences in the treatment and progression with the time and the severity of ARDS were determined. Findings: Among 109 patients, mean age was 55 years, and 59 patients were male. With a median 15 days (range, 4 to 30 days) follow-up period, 31 patients (28.4%) died, while 78 (71.6%) survived and discharged. Of all patients, 53 (48.6%) developed ARDS. Compared to non-ARDS patients, ARDS patients were elder (mean age, 61 years vs. 49 years), and more likely to have the coexistent conditions, including diabetes (20.8% vs. 1.8%), cerebrovascular disease (11.3% vs. 0%), and chronic kidney disease (15.1% vs. 3.6%). Compared to mild ARDS patients, those with moderate and severe ARDS had higher mortality rates. No significant effect of antivirus, glucocorticoid, or immunoglobulin treatment on survival was observed in patients with ARDS. Interpretation: The mortality rate increased with the severity of ARDS in COVID-19, and the effects of current therapies on the survival for these patients were not satisfactory, which needs more attention from clinicians. Funding: Health and Family Planning Commission of Wuhan Municipality.

To understand the unexpected and puzzling long-term stability of nanoscale gas bubbles, it is crucial to probe their nature and intrinsic properties. We report herein synchrotron-based scanning transmission X-ray microscopy (STXM) evidence of highly condensed oxygen gas molecules trapped as surface nanobubbles. Remarkably, the analysis of absorption spectra of a single nanobubble revealed that the oxygen density inside was 1–2 orders of magnitude higher than that in atmospheric pressure, and these bubbles were found in a highly saturated liquid environment with the estimated oxygen concentration to be hundreds of times higher than the known oxygen solubility in equilibrium. Molecular dynamics simulations were performed to investigate the stability of surface nanobubbles on a heterogeneous substrate in gas-oversaturated water. These results indicated that gas molecules within confinement such as the nanobubbles could maintain a dense state instead of the ideal gas state, as long as their surrounding liquid is supersaturated. Our findings should help explain the surprisingly long lifetime of the nanobubbles and shed light on nanoscale gas aggregation behaviors.