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We employed a microwave-assisted two-pot in-situ deposition technique to incorporate zinc oxide particulates in the structure of filter paper to produce antimicrobial paper. The process involved successive immersion of filter paper samples in ZnSO4 (precursor solution) and NaOH (precipitating agent) to form Zn(OH)2, which transformed into ZnO during microwave treatment. Successful deposition of ZnO particles on the filter paper was confirmed via X-ray diffraction and the corresponding morphologies were observed using field emission scanning electron microscopy. The ZnO-deposited papers were tested for antimicrobial activity and were found to be more effective against Staphylococcus aureus (gram-positive) than Escherichia coli (gram-negative). Bacterial populations were reduced by up to 92 ± 2% and 57 ± 4% for S. aureus and E. coli, respectively. Also, it was found that the samples prepared using higher concentrations of ZnSO4 and NaOH exhibited better antimicrobial properties.

Polyaniline-coated papers were fabricated using two-pot layer-by-layer technique. The process involved successive dipping in monomer-acid and oxidant solutions. The infrared spectra showed vibrational modes associated with the presence of polyaniline molecules and cellulose fibers. The polyaniline-coated papers were observed to have electrical and antimicrobial properties. SEM images showed an interconnected network where charges can flow. Measured AC conductivities varied with the amount and configuration of deposits. The values were higher for samples prepared using a larger acid-to-aniline molar ratio. The polyaniline-coated papers were more effective in reducing S. aureus (gram positive) than E. coli (gram negative) after 1 h of contact. The samples’ ability to reduce these bacterial populations decreased after deprotonation.

A zero-field ferromagnetic Ising model is utilized to simulate the propagation of infection in a population that assumes a square lattice structure. The rate of infection increases with temperature. The disease spreads faster among individuals with low J values. Such effect, however, diminishes at higher temperatures., {"references":["HW Hethcote, \"Three basic epidemiological models\", In: Levin, Hallan,\nGross (Eds.), Applied mathematical ecology. Biomathematics, vol. 18,\nNew York: Springer-Verlag, 1989, pp. 119ÔÇö144.","BA Cipra, \"An introduction to the Ising model\", The American\nMathematical Monthly, vol. 94, no. 10, pp. 937--959, 1987.","LF Lopez and E Massad, \"Time-dependent discrete, Ising-like model for\nSIS epidemic systems\", In Proceedings of European Conference on\nMathematical and Theoretical Biology, 2011."]}

Stable nonzero populations without random deaths caused by the Verhulst factor (Verhulst-free) are a rarity. Majority either grow without bounds or die of excessive harmful mutations. To delay the accumulation of bad genes or diseases, a new environmental parameter Γ is introduced in the simulation. Current results demonstrate that stability may be achieved by setting Γ = 0.1. These steady states approach a maximum size that scales inversely with reproduction age.

A large amount of population models use the concept of a carrying capacity. Simulated populations are bounded by invoking finite resources through a survival probability, commonly referred to as the Verhulst factor. The fact, however, that resources are not easily accounted for in actual biological systems makes the carrying capacity parameter ill-defined. Henceforth, we deem it essential to consider cases for which the parameter is unnecessary. This work demonstrates the possibility of Verhulst-free steady states using the Penna aging model, with one semelparous birth per adult. Stable populations are obtained by setting a mutation threshold that is higher than the reproduction age.