Vol. 54 No. 2 (2022)

The biggest public health problem facing the whole world today is the COVID-19 pandemic. From the time COVID-19 came into the limelight, people have been losing their loved ones and relatives as a direct result of this disease. Here, we present a six-compartment epidemiological model that is deterministic in nature for the emergence and spread of two strains of the COVID-19 disease in a given community, with quarantine and recovery due to treatment. Employing the stability theory of differential equations, the model was qualitatively analyzed. We derived the basic reproduction number for both…

Our study examined the mechanism of oxygen reduction reactions (ORR) at the square paddle-wheel cage active site of TM-BTC metal-organic frameworks (MOFs), where TM is a transition metal, Mn, Fe, or Cu. We used a combination of density functional theory (DFT) and microkinetic calculations to investigate this mechanism. By using a small cluster for modeling the TM-BTC active site structure, we successfully reproduced the experimental trend of ORR activity in the TM-BTC systems: Mn-BTC > Fe-BTC > Cu-BTC. We also found that the unusual ORR activity trend in experiments for Mn and Fe systems…

Gyrinops versteegii is widely used in the perfume, incense, and cosmetic industries as a raw material. Other potential uses of the plant are being explored, including in food and medicine. Therefore, this study carried out antibacterial assay and gas chromatography-mass spectroscopy of G. versteegii fruit extracts in three solvents with different polarities, i.e., n-hexane, dichloromethane, and methanol. The agar well diffusion method was then used to test the extracts against Staphylococcus aureus and Escherichia coli. The dichloromethane extract showed the most effective antibacterial…

Two complexes of [Mn(Quin)2(N(CN)2)2]∞ (1) and [Co(Quin)2(N(CN)2)2]∞ (2) were synthesized and characterized. The as-synthesized complexes crystallized in a triclinic lattice with a space group of P-1. The unit cell parameter of 1 was a = 7.5207(14) Å, b = 7.7729(16) Å, c = 9.5968(15) Å, α = 96.388(6) o, β = 112.617(5) o, γ = 102.751(6) o, while for complex 2 it was a = 7.3942(10) Å, b = 7.7960(10) Å, c = 9.4907(13) Å, α = 96.631(4) o, β = 112.742(4) o, γ = 102.458(4) o. The magnetic properties and antimicrobial properties of both polymeric complexes were examined by magnetic susceptibility…

Population growth causes the demand for food to increase. One solution that can be applied is agriculture with hydroponic technology. To increase production efficiency, one must know the physical parameters that most influence the production process. This research used an IoT system to gather accurate and precise measurement data of physical parameters to be used as a dataset for machine learning. The dataset consisted of light intensity, humidity, air temperature, and total dissolved solids (TDS). Plant growth was measured by leaf area of the plant, number of leaves, and plant stem length…