COVID-19 has become a global pandemic and requires the whole world to respond together. There is no specific antiviral treatment recommended at present for COVID-19. The patients must receive the supportive care to help relieve the symptoms and ensure appropriate infection control. Whether or not to use corticosteroids clinically caused controversy. This article has summarized previous researches about the using of corticosteroids in other viral pneumonia, related clinical data in COVID-19, and recommendations in Chinese guideline.
Influenza pandemics with different extent occur every year in the world. It can cause high morbidity and mortality, arouse fear panic in public, and attract extensive attention worldwide. This paper reviews the research progress in epidemiological characteristics, detection methods, pathogenesis, treatment and prophylactic measures of influenza in China. It will be helpful for us to understand the current situation of influenza.
Since China adopted the reform and open-up policy in the late 1970s, cultural semiotics from the former Soviet Union has been introduced into China, and has exerted substantial influence on Chinese academia. This essay starts from the perspective of research discourse to review the influence of Soviet literary theories among Chinese scholars over the past half century, and to demonstrate the positive role played by Soviet cultural semiotics in the evolution process of the Chinese literary community from revolution through aesthetic discourse to dialogue and polyphony. The essay then proceeds to the discussion of the revolutionary shift in the critical mindset caused by the changes in research discourses, namely the shift from the scientific way of thinking, featuring scientific induction, to the artistic way of thinking, featuring pluralism and the co-existence of various elements. The last part of the essay provides an in-depth discussion of the Chinese adaptation of Soviet cultural semiotics, i.e. the rediscovery of the nature of cultural semiotics by Chinese semioticians.
Co-injection molding (CIM) is an advanced technology which was developed to meet quality requirements and to reduce the material cost. Theoretical investigations concerning it are very limited, especially for simultaneous CIM. The interactions of air, skin and core polymer melt in the process are very complex, which makes it more challenging to simulate free surface flows in the mold. Thus, this article presents a mathematical model for it. The extended Pom-Pom (XPP) model is selected to predict the viscoelastic behavior of polymer melt. The free surface is captured by the level set method. The article vividly shows the simultaneous CIM process by means of a visual numerical simulation technique. Both two-dimensional (2D) and 3D examples are presented to validate the model and illustrate its capabilities. The 3D flow behaviors of simultaneous CIM process are hard to predict numerically. To our knowledge, this is the first attempt at simulating melt flow behaviors in 3D simultaneous CIM based on the XPP constitutive equation and visual technique. The numerical results are in good agreement with the available experiment results, which establish the capability of the multiphase flow model presented in this article to simulate the flow behaviors of polymer melt in simultaneous CIM process.