RESUMO
The outbreak of COVID-19 has caused tremendous pressure on medical systems. Adequate isolation facilities are essential to control outbreaks, so this study aims to quickly estimate the demand and number of isolation beds. We established a discrete simulation model for epidemiology. By adjusting or fitting necessary epidemic parameters, the effects of the following indicators on the development of the epidemic and the occupation of medical resources were explained: (1) incubation period, (2) response speed and detection capacity of the hospital, (3) disease cure time, and (4) population mobility. Finally, a method for predicting the reasonable number of isolation beds was summarized through multiple linear regression. The prediction equation can be easily and quickly applied to estimate the demanded number of isolation beds in a COVID-19-affected city. A detailed explanation is given for the specific measurement of each parameter in the article.
RESUMO
OBJECTIVE：To provide reference for improving the quality sta ndard of Equisetum hyemale . METHODS ：Totally 10 batches of E. hyemale from different sites were collected as samples. TLC method was used to qualitatively identify kaempferol- 3-O-β-sophoroside. The contents of heavy metal ，aflatoxin，impurity，moisture，total ash ，acid-insoluble ash ，water-soluble extract and ethanol-soluble extract were determined according to supplementary provisions of Chinese Pharmacopoeia （2015 edition）. HPLC method was used to determine the content of kaempferol- 3-O-β-sophoroside in sample. HPLC fingerprint of water-soluble extract from E. hyemale was also established. RESULTS ：TLC identification showed that in the chromatogram of the test sample ， fluorescent spots with the same color were displayed on the corresponding positions of the chromatogram of substance control of kaempferol-3-O-β-sophoroside，and without interference from blank control. Among 10 batches of samples ，the contents of impurities were 0.19％-2.32％；the water contents were 10.12％-11.87％；the total ash contents were 6.67％-10.11％；the acid-insoluble ash contents were 1.34％-2.12％；the water-soluble extract contents were 9.17％-13.99％；the ethanol-soluble extract contents were 7.49％-13.68％，respectively. It is preliminarily proposed that the impurity content shall not exceed 3.00％；the total ash content shall not exceed 10.00％；the acid-insoluble ash content shall not exceed 2.50％；the water-soluble extract content shall not be less than 9.00％ ；the ethanol-soluble extract content shall not be less than 5.00％. Arsenic（0.064-0.225 mg/kg） 010815） was detected in 9 batches of samples ；cadmium（0.106-0.132 E-mail：cruise0303@163.com mg/kg）was detected in 6 batches of samples ；lead（0.221- 1.896 mg/kg）was detected in all samples ，but no mercury or rebecca aflatoxin was detected. The results of HPLC method met the relevant requirements of Chinese Pharmacopoeia . The content of kaempferol- 3-O-β-D-sophoroside in 10 batches of samples was 627.12-5 384.53 mg/kg，and the similarity of HPLC fingerprints of 10 batches of samples was more than 0.900. CONCLUSIONS ： A new qualitative and quantitative analysis method for kaempferol- 3-O-β-D-sophoroside was established ；the heavy metals ， aflatoxins，impurities and other items in E. hyemale were detected ；the limits of impurity ，ash and extract were determined. The established method is simple ，accurate and reproducible ，and can be used for quality control of E. hyemale .
