RESUMO
When encountering the outbreak and early spreading of COVID-19, the Government of Japan imposed gradually upgraded restriction policies and declared the state of emergency in April 2020 for the first time. To evaluate the efficacy of the countering strategies in different periods, we constructed a SEIADR (susceptible-exposed-infected-asymptomatic-documented-recovered) model to simulate the cases and determined corresponding spreading coefficients. The effective reproduction number R t was obtained to evaluate the measures controlling the COVID-19 conducted by the Government of Japan during different stages. It was found that the strict containing strategies during the state of emergency period drastically inhibit the COVID-19 trend. R t was decreased to 1.1123 and 0.8911 in stages 4 and 5 (a state of emergency in April and May 2020) from 3.5736, 2.0126, 3.0672 in the previous three stages when the containing strategies were weak. The state of emergency was declared again in view of the second wave of massive infections in January 2021. We estimated the cumulative infected cases and additional days to contain the COVID-19 transmission for the second state of emergency using this model. R t was 1.028 which illustrated that the strategies were less effective than the previous state of emergency. Finally, the overall infected population was predicted using combined isolation and testing intensity; the effectiveness and the expected peak time were evaluated. If using the optimized control strategies in the current stage, the spread of COVID-19 in Japan could be controlled within 30 days. The total confirmed cases should reduce to less than 4.2 × 105 by April 2021. This model study suggested stricter isolating measures may be required to shorten the period of the state of emergency.
Assuntos
COVID-19/epidemiologia , COVID-19/transmissão , Emergências , Modelos Biológicos , Pandemias , SARS-CoV-2 , Algoritmos , COVID-19/prevenção & controle , Teste para COVID-19/métodos , Teste para COVID-19/estatística & dados numéricos , Controle de Doenças Transmissíveis/legislação & jurisprudência , Controle de Doenças Transmissíveis/métodos , Controle de Doenças Transmissíveis/estatística & dados numéricos , Biologia Computacional , Simulação por Computador , Humanos , Japão/epidemiologia , Análise dos Mínimos Quadrados , Conceitos Matemáticos , Modelos Estatísticos , Programas Nacionais de Saúde/legislação & jurisprudência , Dinâmica não Linear , Pandemias/prevenção & controle , Pandemias/estatística & dados numéricosRESUMO
OBJECTIVE: To study the best technology of the extraction of triterpenoids from the stems of Hyptis suaveolens with microwave. METHODS: Orthogonal experiment was carried out to investigate 4 influential factors as follows: the time (A), the temperature (B), the solid fluid compared to (C), the NaOH density (D). RESULTS: The optimal conditions for microwave extraction were A1 B2 C3 D2. CONCLUSION: The microwave extraction can extract more triterpenoids from the stems of Hyptis suaveolens in shorter time with less energy. It also shows a promising prospect for leaching the effective constituents from Chinese herbal medicine by using microwave extraction.