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The coronavirus disease 2019 (COVID-19) is spreading rapidly all over the world. The transmission dynamics of the COVID-19 pandemic is still unclear, but developing strategies for mitigating the severity of the pandemic is yet a top priority for global public health. In this study, we developed a novel compartmental model, SEIR-CV(susceptible-exposed-infectious-removed with control variables), which not only considers the key characteristics of asymptomatic infection and the effects of seasonal variations, but also incorporates different control measures for multiple transmission routes, so as to accurately predict and effectively control the spread of COVID-19. Based on SEIR-CV, we predicted the COVID-19 epidemic situation in China out of Hubei province and proposed corresponding control strategies. The results showed that the prediction results are highly consistent with the outbreak surveillance data, which proved that the proposed control strategies have achieved sound consequent in the actual epidemic control. Subsequently, we have conducted a rolling prediction for the United States, Brazil, India, five European countries (the United Kingdom, Italy, Spain, Germany, and France), southern hemisphere, northern hemisphere, and the world out of China. The results indicate that control measures and seasonal variations have a great impact on the progress of the COVID-19 pandemic. Our prediction results show that the COVID-19 pandemic is developing more rapidly due to the impact of the cold season in the southern hemisphere countries such as Brazil. While the development of the pandemic should have gradually weakened in the northern hemisphere countries with the arrival of the warm season, instead of still developing rapidly due to the relative loose control measures such as the United States and India. Furthermore, the prediction results illustrate that if keeping the current control measures in the main COVID-19 epidemic countries, the pandemic will not be contained and the situation may eventually turn to group immunization, which would lead to the extremely severe disaster of about 5 billion infections and 300 million deaths globally. However, if Chinas super stringent control measures were implemented from 15 July, 15 August or 15 September 2020, the total infections would be contained about 15 million, 32 million or 370 million respectively, which indicates that the stringent and timely control measures is critical, and the best window period is before September for eventually overcoming COVID-19. SignificanceCOVID-19 is now posing a huge threat to global public health. The key features such as asymptomatic infection and droplet or airborne transmission make COVID-19 more easily spread and more widely distributed around the world. It is an urgent need to explore the optimal intervention strategies and measures to contain the pandemic. Our novel SEIR-CV compartmental model considers the new features of COVID-19, exhibits the impact of the intervention strategies and seasonal variations, and thus can accurately predicts its trajectory in China and the rest of the world. Our research results suggest that control measures and seasonal variations have a great impact on the development of the COVID-19 pandemic, which can only be contained by stringent strategies during the best window period before September 2020 for eventually overcoming COVID-19, otherwise it would cause a severer global catastrophe.
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Objective To establish a quick electrochemical biosensor for the detection of nucleic acid of Ebola virus . Methods The DNA tetrahedral nanostructure was self-assembled on gold surface by strong Au-S chemical bonds , leaving the target probe at the top .A biotinylated-ssDNA was introduced as the detection probe by specific binding of the captured target sequence , before avidin-horseradish peroxidase ( HRP) was used as a signal amplifier to transduce amperometric sig-nal through interactions with TMB substrate .Results The results indicated that the nucleotide sequence of Ebola virus could be recognized and detected by the sensor .The linear range for the detection of target DNA was from 1.0 ×10 -9 to 5.0 ×10 -6 mol/L,and the detection limit was 5.2 ×10 -10 mol/L.Conclusion The fabricated sensor is demonstrated to be sensitive and specific for the detection of Ebola virus nucleotide .
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Rapid detection of infection pathogens is of great importance to the prevention and control of infectious diseases.Compared with traditional approaches,point-of-care testing (POCT) technologies promise great advantages in simple, rapid and portable detection of pathogens.In this review, the technologies, categories, developments and applications of POCT in detection of infectious pathogens are elaborated.Furthermore, the future developments of POCT detection of infectious pathogen are also discussed.This review focuses on loop-mediated isothermal amplification ( LAMP) technology, microfluidic chip and biosensor technology in the POCT detection of infectious pathogens while elaborating on the application of these new technologies associated with POCT detection.
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Objective To develop a portbable incubator for on-site cultivation of microorganisms in foods and drinking water.Methods Cultivation temperature was set as required by the temperature for various microorganisms and PID was controlled via the single chip microcomputer and configuration screen .Then, the framework of the incubator was designed and assembled.Finally, the cultivation effect was tested .Results The incubator was compact and portable .The deviation of the temperature was in the range of 1℃.The hold time of self-contained power could exceed 8 h.In addition, the cultivation effect of our fabricated incubator was not significantly different from that of the commercial electro-heating standing-temperature cultivator used in laboratories .Conclusion The incubator is suitable for on-site detection of microorganisms in foods and drinking water , which is significant for spotting and removing the hidden dangers from microorganism contaminations in foods and drinking water in order to protect the health of soldiers .
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Rapid detection of pathogenic microorganisms is important to the prevention and control of diseases.Com-pared with traditional approaches, electrochemical DNA biosensors present great advantages in promising rapid, portable, sensitive and cost-saving detection of pathogens.In this review, the working principle of electrochemical DNA biosensors and the progress in detection of pathogens is introduced, the latest developments of DNA tetrahedron structure and new nano materials in electrochemical DNA biosensors are reviewed, and the challenges to and prospects of development in this field are also discussed.
