Electromagnetic Attenuation Characteristics of Microbial Materials in the Infrared Band

Abstract

In this study, seven microbial materials (entomogenous fungi Bb3088 mycelia, entomogenous fungi Bb3088 spores, entomogenous fungi Ma2677 mycelia, entomogenous fungi Ma2677 spores, Bacillus subtilis 8204, Staphylococcus aureus 6725, and Saccharomyces cerevisiae 1025) were used to measure electromagnetic (EM) signal extinction. They were subjected to light absorption and reflection measurements in the range of 4000-400 cm(-1) (2.5-25 µm) using Fourier transform infrared spectroscopy. The specular reflection spectrum method was used to calculate the real (n) and imaginary (k) parts of the complex refractive index. The complex refractive index with real part n and imaginary part k in the infrared band satisfies the following conditions n ≥ 1 and k ≥ 0. The mass extinction coefficient was calculated based on Mie theory. Entomogenous fungi Ma2677 spores and entomogenous fungi Bb3088 spores were selected as EM signal extinction materials in the smoke box test. The transmittances of entomogenous fungi Bb3088 spores and entomogenous fungi Ma2677 spores were 11.63% and 5.42%, and the mass extinction coefficients were 1.8337 m(2)/g and 1.227 m(2)/g. These results showed that entomogenous fungi Bb3088 spores and entomogenous fungi Ma2677 spores have higher extinction characteristics than other microbial materials.

Significant broadband extinction abilities of bioaerosols

“…They were isolated by the laboratory and stored at −80°C in sterilized cryovials containing 10% glycerol (in 0.02% Tween-80 solution). We optimized the fermentation conditions to improve the collection efficiency for the biomaterials production [27][28][29]: bacterial species activation→shake flask culture→large-scale tank fer-mentation→centrifugation→pure water cleaning→vacuum freeze-drying→crushing using a ultra-fine Chinese medicine crusher (See the supplementary information, text section for specific steps). And then the biomaterials were stored in desiccators containing silica gel absorbent ( Fig.…”

“…Based on the measured reflection spectra, the complex refractive index values of the bioaerosols in the 240 nm-14 μm wavelength range were calculated using the Kramers-Kronig (K-K) relation [30][31][32][33]. Our group have previously used this method for calculating the complex refractive index of biomaterials [27,[34][35][36][37][38][39][40][41][42][43][44]. According to this relation, the reflective phase shift Θ(λ) can be expressed as [45] ( )…”

Optimized shape and structure of artificial bioparticles to enhance the optical extinction properties

“…The fermentation conditions have been optimized to improve the collection efficiency for bioaerosol materials production. 6,38,39 Through the process of strain activation, shaking flask culture, large tank fermentation, centrifugation, pure water cleaning, vacuum freezing and drying, and grinding with a superfine Chinese medicine grinder, 40 the samples were prepared. The samples were stored in a dry dish with silica gel at room temperature.…”

“…Therefore, considerable attention has been paid to microbial materials recently. 6,7 The multilayer structure of microbial cells leads to multiple reflection, refraction, and absorption attenuation of electromagnetic waves, which makes biological particles have a strong ability to extinguish light. Different types, numbers, and morphologies of nuclei, cell walls, cell membranes, and organelles lead to differences in the extinction ability of bioparticles.…”

Infrared Extinction Performance of Randomly Oriented Microbial-Clustered Agglomerate Materials

“…However, there are certain restrictions on the use of inorganic materials, such as high production cost, long growth cycle, and environmental harmfulness. Recently, considerable attention has been paid to microbial materials 1,2 that have the potential to solve the problems noted above. Microbial materials have some unique advantages, such as short growth cycle, stable property, and free from contamination.…”