Journal of Mathematical and Fundamental Sciences

Mathematical Analysis of Two Strains Covid-19 Disease Using SEIR Model

Adetayo Samuel Eegunjobi, Oluwole Daniel Makinde — Wed, 28 Dec 2022 00:00:00 +0700

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 strains and investigated the sensitivity index of the parameters. In addition to this, we probed the global stability of the disease-free equilibrium. The disease-free equilibrium was revealed to be globally stable, provided and the model exhibited forward bifurcation. A numerical simulation was performed, and pertinent results are displayed graphically and discussed.

Oxygen Reduction Reaction Mechanism on the Square Paddle-Wheel Cage Site of TM-BTC (TM=Mn, Fe, Cu) Metal-Organic Framework

Wed, 28 Dec 2022 00:00:00 +0700

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 originates from the strength of OH adsorption on these systems. The Mn-BTC system exhibits higher ORR activity than the Fe-BTC system due to its weaker adsorption of OH groups. A very strong OH adsorption makes the final OH reduction step sluggish, hence hindering the ORR process.

Antibacterial Activity of Gyrinops versteegii Fruit Extracts against Staphylococcus aureus and Escherichia coli and GC-MS Analysis

Ernin Hidayati, Yuli Handayani, I Made Sudarma — Sat, 04 Mar 2023 00:00:00 +0700

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 activity against S. aureus at a concentration of 40%, with a zone of inhibition of 13.17 mm compared to E. coli, for which it was 7 mm. Furthermore, the bacterial species showed different responses to the extracts. Total and partial inhibition was shown by the G. versteegii fruit extracts against S. aureus and E. coli, respectively. Furthermore, GC-MS identified the following compounds in G. versteegii fruit extract: palmitic, oleic, and stearic acid, as well as bis-(2-ethylhexyl) phthalate, 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one, methyl octadec-9-enoate, squalene, and 2-monopalmitin derivates. The results showed antibacterial potency of G. versteegii fruit extract against pathogenic bacteria. Additionally, the antibacterial activity of the extract was stronger against S. aureus compared to E. coli.

Synthesis, Structure, Magnetic and Antibacterial Properties of polymeric [M(Quin)2(N(CN)2)2]∞ (M = Mn(II), Co(II); Quin = quinoline)

Sun, 19 Mar 2023 00:00:00 +0700

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 and diffusion techniques, respectively. Complexes 1 and 2 both showed antiferromagnetic properties and had a higher inhibitory effect on the growth of Staphylococcus aureus than Salmonella typhi.