An SIR epidemic model for COVID-19 spread with fuzzy parameter: the case of Indonesia.

The aim of this research is to construct an SIR model for COVID-19 with fuzzy parameters. The SIR model is constructed by considering the factors of vaccination, treatment, obedience in implementing health protocols, and the corona virus-load. Parameters of the infection rate, recovery rate, and death rate due to COVID-19 are constructed as a fuzzy number, and their membership functions are used in the model as fuzzy parameters. The model analysis uses the generation matrix method to obtain the basic reproduction number and the stability of the model's equilibrium points. Simulation results show that differences in corona virus-loads will also cause differences in the transmission of COVID-19. Likewise, the factors of vaccination and obedience in implementing health protocols have the same effect in slowing or stopping the transmission of COVID-19 in Indonesia.

New naphthoquinone derivatives from Fusarium napiforme of a mangrove plant.

Two new naphthoquinone derivatives, 6-hydroxy-astropaquinone B (1) and astropaquinone D (2) as well as the known compound 3-O-methyl-9-O-methylfusarubin (3) were isolated from Fusarium napiforme, an endophytic fungus isolated from the mangrove plant, Rhizophora mucronata. The structures of 1 and 2 were determined by 1D and 2D NMR spectroscopic analyses. Compounds 1, 2 and 3 exhibited moderate antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa. Furthermore, 1, 2 and 3 were phytotoxic action in lettuce seeding at a concentration of 30 µg · mL-1.

Stability analysis and numerical simulation of SEIR model for pandemic COVID-19 spread in Indonesia.

The Aim of this research is construct the SEIR model for COVID-19, Stability Analysis and numerical simulation of the SEIR model on the spread of COVID-19. The method used to construct the model is the SEIR model by considering vaccination and isolation factors as model parameters, the analysis of the model uses the generation matrix method to obtain the basic reproduction numbers and the global stability of the COVID-19 distribution model. Numerical simulation models use secondary data on the number of COVID-19 cases in Indonesia. The results obtained are the SEIR model for COVID-19; model analysis yields global stability from the spread of COVID-19; The results of the analysis also provide information if no vaccine, Indonesia is endemic COVID-19. Then the simulation results provide a prediction picture of the number of COVID-19 in Indonesia in the following days, the simulation results also show that the vaccine can accelerate COVID-19 healing and maximum isolation can slow the spread of COVID-19. The results obtained can be used as a reference for early prevention of the spread of COVID-19 in Indonesia.