Background: The outbreak of coronavirus disease 2019 (COVID-19) is now becoming an enormous threat to public health. The clinical spectrum of COVID-19 is extensive, of which critical cases are with rapid disease progression and high mortality. The aim of our study is to summarize the characteristics of different subtypes and explore risk factors of illness severity for early identification and prompt treatment. Methods: In this retrospective study, we collected data of patients confirmed COVID-19 in Zhejiang Province from 17 January to 12 February 2020. According to the definition of clinical classification, we divided confirmed cases into four types, and summarize epidemiological and clinical characteristics, laboratory and radiograph findings, treatments, and outcomes, respectively. Moreover, we used univariate and multivariate ordinal logistic regression models to explore risk factors for the severity of illness in patients with COVID-19. Results: A total of 788 patients were enrolled in our study, of whom 52 cases (6.6%) were mild type, 658 cases (83.5%) were common type, 61 cases (7.2%) were severe type, and 17 cases (2.2%) were critical type. Multivariate ordinal logistic regression demonstrated increasing odds of the severity of illness in patients with COVID-19 associated with male (odds ratio [OR] = 1.7, 95% confidence interval [

Template-activated strategy was developed to coat silica (SiO2) colloidal microspheres with silver in one step, based on one-pot hydrothermal treatment of silver nitrate, PVP (poly(vinyl pyrrolidone)), and SiO2 colloidal microspheres in ammonia solution. In our reaction system, the surface of SiO2 colloidal microspheres was continually activated with negative-charged SiO(-) groups in ammonia solution, which accumulated [Ag(NH3)2](+) or Ag(+) ions around the SiO2 colloidal microspheres through electrostatic attraction; thereafter these ions could be reduced into Ag nanoparticles in situ by the weak reducer PVP in the solution, and then acted as seeds for the subsequent complete silver coating with the reaction proceeding. Therefore, the traditional three steps for complete silver coating, including prior surface modification, seeding, and subsequent growing, were effectively integrated into one step. The experimental results exhibited that perfect SiO2/Ag core/shell composite microspheres were successfully synthesized through optimizing the reaction parameters like the solvent ingredient, reducer, and the reaction temperature. Additionally, these obtained uniform composite microspheres were further used as SERS substrate by using R6G and thiram as probe molecules, and showed excellent trace detection of these organic chemicals in solution.

Well-dispersed magnetic-based silver composite microspheres (Fe 3 O 4 @SiO 2 @Ag) with a nanosheetassembled shell structure were synthesized at room temperature, where sonicating and mechanical stirring techniques were both employed and played important roles during the silver shell growth process. The results show that the nanosheet-assembled silver shell could be obtained and controlled by adjusting the concentration of citrate ions as a morphology directing-reagent. The gaps in or between cross-linked nanosheets in the shell of the composite microspheres were proposed to provide sufficient "hot spots" when they were used as a SERS substrate. The SERS measurements exhibit clear enhancement signals by using R6G as a probe molecule, and even at concentrations as low as 10 À14 M, all enhancement peaks could be observed clearly. The film assembled from the composite microspheres exhibited good reproducibility across the entire area. Additionally, the magnetic Fe 3 O 4 @SiO 2 @Ag microspheres can be separated from solution rapidly, which shortened the detection time. Considering their excellent SERS performance, this kind of composite microsphere, which has both a SERS active shell and a magnetically separable core, would be very useful as an effective SERS substrate for detecting organic pollutants in solution.

Homogeneous Ag nanosheet-assembled film was successfully fabricated by using Cu plate through a simple modified solution method, where weak reductive Cu2O layer and complexing agent citrate ions were both introduced into the reaction system to control the reaction process. Meanwhile, citrate ions were used as morphology-controlled reagent to lead Ag units to grow in the form of nanosheet. The growth process exhibited that Ag nanosheet-assembled film formed slowly with reaction proceeding. Additionally, the pack density of nanosheets in the final product was found to be adjusted by the concentrations of Ag(+) ions in precursor solution. Using Rhodamine 6G (R6G) as probing molecules, the surface-enhanced Raman scattering (SERS) experiments showed that the Ag film assembled by nanosheets with high pack density exhibited excellent detecting performance, which could be used as effective SERS substrate for ultrasensitive detecting. Besides, a novel quintuplet SERS substrate could be synthesized in one batch by our method, which showed good reproducibility and a linear dependence between analyte concentrations and intensities, revealing the advantage of this method for easily scale-up production.

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