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Background Since December, 2019, the emerge of a Novel Coronavirus Disease 2019 (COVID-19) have caused global concern, the majority viewpoints are that the deaths are related to advanced ages, however, the emergence of younger deaths needs immediate attention. Methods Clinical characteristics, laboratory results, chest CT scans and treatment measures were retrospectively reviewed for six deceased patients under 60 years old with confirmed COVID-19 who were admitted to Wuhan Pulmonary Hospital in Wuhan, Hubei Province, China, from 6th January to 4th March, 2020. Results The age range of the patients was 50.17 ± 3.25 years (45–55 years), none of them had underlying diseases. All of patients presented with the symptoms of fever, respiratory system and digestive system. The level of albumin and lymphocyte counts decreased early in the stages of the disease, and then gradually increased. The neutrophil to lymphocyte ratio (NLR) increased (higher than normal range) in early stage and gradually decreased when the disease progressed. All the six patients showed ground-glass opacity (GGO) and bilateral patchy shadowing in early stage under the computed tomography (CT). All the patients died of severe pneumonia and multiple organ failure. Conclusions The decreased level of serum albumin occurred in the early stages of the disease, and delays in the first admission to hospital probably aggravate the disease development. The increase of the NLR in early stage of disease may be a risk of death for COVID-19. These findings may provide useful information for optimizing supportive care for COVID-19 pneumonia.

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Considering the nonlinear mechanical-magnetic coupling effects, an accurate mathematical model was established for analyzing large stroke penta-stable mechanism possessing multistability transforming capability, with which the mechanism can be switched from pentastability to quadristability. The multistability with any number of stable states can be achieved by integrating spatially arranged magnets and large deformation beams as the fundamental energy storage elements to maintain stable states. By theoretically analyzing the influence of the large mechanical deformation on the magnetic field distribution and system energy, the nonlinear force–displacement characteristics of the multistable mechanism were obtained numerically, which were in good agreement with those obtained by experiments and finite element simulation. Then, an energy-based design criterion for magnetic-mechanical multistable mechanisms was proposed according to the stability theory and energy variation principle. In addition, the multistable transformability was theoretically analyzed, which can transform the proposed mechanism from penta-stability to quadristability by only changing the magnetization direction of moving magnets without varying the structure parameters.