Assess Medical Screening and Isolation Measures Based on Numerical Method for COVID-19 Epidemic Model in Japan

This study aims to improve control schemes for COVID-19 by a numerical model with estimation of parameters.We established a multi-level and multi-objective nonlinear SEIDR model to simulate the virus transmission.The early spread in Japan was adopted as a case study.The first 96 days since the infection were divided into five stages with parameters estimated.Then,we analyzed the trend of the parameter value,age structure ratio,and the defined PCR test index(standardization of the scale of PCR tests).It was discovered that the self-healing rate and confirmed rate were linear with the age structure ratio and the PCR test index using the stepwise regression method.The transmission rates were related to the age structure ratio,PCR test index,and isolation efficiency.Both isolation measures and PCR test medical screening can effectively reduce the number of infected cases based on the simulation results.However,the strategy of increasing PCR test medical screening would encountered a bottleneck effect on the virus control when the index reached 0.3.The effectiveness of the policy would decrease and the basic reproduction number reached the extreme value at 0.6.This study gave a feasible combination for isolation and PCR test by simulation.The isolation intensity could be adjusted to compensate the insufficiency of PCR test to control the pandemic.

A new insight into aggregation structure of organic solids and its relationship to room-temperature phosphorescence effect

In order to improve the performance of organic luminescent materials,lots of studies have been carried out at the molecular level.However,these materials are mostly applied as solids or aggregates in practical applications,in which the relationship between aggregation structure and luminescent property should be paid more attention.Here,we obtained five phenothiazine 5,5-dioxide(O-PTZ)derivatives with distinct molecular conformations by rational design of chemical structures,and systematically studied their room-temperature phosphorescence(RTP)effect in solid state.It was found that O-PTZ dimers with quasi-equatorial(eq)conformation tended to show strongerπ-πinteraction than quasi-axial(ax)conformers in crystal state,which was more conducive to the generation of RTP.Based on this result,a multi-level structural model of organic solids was proposed to draw the relationship between aggregation structure and RTP effect,just like the research for the structureproperty relationship of proteins.Using this structural model as the guide,boosted RTP efficiency from 1%to 20%was successfully achieved in the corresponding host-guest doping system,showing its wide applicability.