Ecology of microorganisms in the conditions of permafrost

The results of research into the ecology of pathogens of infectious diseases in permafrost conditions are presented. The work was carried out in laboratory conditions and horse breeding farms of the Republic of Sakha (Yakutia), located in the permafrost zone. Isolation and identification of pathogenic and conditionally pathogenic microorganisms were carried out by generally accepted methods used in microbiological practice. The survival rate of microorganisms was studied by methods of veterinary sanitation. The studies conducted showed that the survival time of some microorganisms on the objects of the environment in permafrost conditions is 2-3 times longer than the survival time of similar microorganisms in the southern and European territories of Russia and abroad. When studying microbial contamination and the survival time of microorganisms, a significant content of aerobic spore-forming bacteria (more than 2 x 106 CFU/g) in permafrost soils of Central Yakutia was established. Isolation of viable bacteria of the genus Bacillus from representatives of mammoth fauna preserved in permafrost soils (age 30-40 thousand years) proves the role of permafrost in the preservation of bacteria of the Pleistocene period. Permafrost contributes to the long-term preservation of foci and transmission factors of pathogens of infectious diseases. Isolation of pathogens of yersiniosis from the surfaces of glaciers and from wild animals indicates the danger of contamination of food during storage and consumption. The establishment of the circulation of pathogens of viral diseases among reindeer suggests the role of migratory birds in the spread of infectious diseases. The study of the epizootology of anthrax remains relevant. Knowledge of the survival time of microorganisms on the objects of the environment in the extreme conditions of the Far North and the study of the microbiota of wild animals and migratory birds are necessary to optimize antiepizootic and epidemiological measures in the prevention or elimination of infectious diseases in humans and animals.

Implicit, Intrinsic, Extrinsic (or Environmental), and Host Factors Attributing the Covid-19 Pandemic. Part 2- Implicit Factor Pesticide Use: A Systematic Analysis

Advances in our understanding of complex COVID-19 pandemic would allow us to effectively eliminate and eradicate SARS-COV2 virus. Although tremendous amount of research devoted to the robustness across its biology, diagnostics, vaccines and treatment has exploded in the past two years. However, still science do not have robust answers for causes, for example (i) What are the reasons of non-uniform global distribution of COVID-19? (ii) Why the United States, India, and Brazil, are the first-three most affected nations?, (iii) How did Bhutan, a nation sharing a boundary with China manage nearly 0.34% infections and 3 deaths from COVID-19? Nonetheless, the biomass bistribution of biosphere report suggest more than 1550-fold larger microbial biomass involving bacteria, fungi, archaea, protists and viruses is exist in comparision to all global human population in the biosphere. The rich microbiota act a first line of defence to invade pathogens and affect us both through the environment and microbiome. Unfortunately, a role of pathogen-transmission factors viz. implicit factors (competitive microflora) is still under represented. This study is an attempt from a gold standard correlation methodology using a large pesticide use global data. The non-specific pesticides kill both pests as well as protective microbiota, resulting a loss in rich biodiversity and allow easy pathogen entry to human. Entire predictions were found consistent with the recently observed evidences. These insights enhanced scientific ability to interrogate viral epidemiology and recommended to limit pesticide use for future pandemic prevention.

Radiation attenuation properties of B2O3-ZnO-Al2O3-Bi2O3-Sm2O3 glasses

The goal of this study is to examine theoretically radiation absorption properties of zinc alumino bismuth borate (BZnAlBiSm) glasses with chemical formula 60B2O3-9ZnO-(30-x)Al2O3-xBi2O3-1Sm2O3 where x = 5, 10, 15 and 20 mol%. The linear and mass attenuation coefficents of BZnAlBiSm glasses turn out as this trend BZnAlBiSm-1<BZnAlBiSm-2<BZnAlBiSm-3<BZnAlBiSm-4. The BZnAlBiSm-4 with the smallest half value layers, tenth value layers and mean free paths in the examined energy ranges has the superior radiation shielding characteristics among the BZnAlBiSm glasses. The BZnAlBiSm-4 glass has the highest radiation protection efficiency among the BZnAlBiSm glasses. The transmission factors increase as photon energy range enhances from 0.015 to 15 MeV and thickness declines from 2.5 to 0.5 cm. The energy buildup factors and energy absorption buildup factors of BZnAlBiSm glasses reduce from 15 to 1 mfp. Variation of the effective atomic number and effective electron density as a function of photon energy for BZnAlBiSm glasses are similar. The projected ranges of electron, proton, alpha and carbon for the BZnAlBiSm glasses increase as photon energy enlarges. The fast neutron removal cross sections of the BZnAlBiSm glasses vary in order of BZnAlBiSm-4<BZnAlBiSm-3<BZnAlBiSm-2<BZnAlBiSm-1. Thus, it can be concluded that BZnAlBiSm-1 has the highest neutron absorption ability among the BZnAlBiSm glasses.

Effects of Reducing PbO Content on the Elastic and Radiation Attenuation Properties of Germanate Glasses: A New Non-toxic Candidate for Shielding Applications

This work presents a detailed study on the effects of reducing PbO content on the elastic and radiation shielding properties of germanate glasses described by the chemical formula 50GeO2-(50-x)PbO-xZnO, where x between 0 and 50 mol % with step of 10. A theoretical analysis based on Makishima-Mackenzie's theory (MM-theory) was employed to obtain the elastic moduli of the studied glass specimens. Moreover, the Monte Carlo simulations were applied via Geant4 platform to assess the radiation shielding ability of the GeO2-PbO-ZnO glass system by evaluating several fundamental properties such as gamma and neutron transmission factors, total cross sections, effective atomic numbers, 1/e penetration depths, and exposure buildup factors. We found that the bulk elastic modulus increased from 50.751 GPa to 85.389 GPa as the PbO content increased from 50 mol % to 0. The results of the linear attenuation coefficient show that the cross sections of (σ)PE, (σ)CE, and (σ)pp dominates the photon attenuation at 0.15 ≤ E ≤ 0.08; 0.8 < E < 8, and 8 < E < 15 MeV respectively. Moreover, the present glasses have superior photon absorbing capacity compared to ordinary and barite concrete; RS-253-G18 and RS-360 commercial glass shields. This suggests that the GeO2-PbO-ZnO glass system can be used as a non-toxic shielding material in the nuclear facilities.

Mechanistic transmission modeling of COVID-19 on the Diamond Princess cruise ship demonstrates the importance of aerosol transmission

Several lines of existing evidence support the possibility of airborne transmission of coronavirus disease 2019 (COVID-19). However, quantitative information on the relative importance of transmission pathways of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains limited. To evaluate the relative importance of multiple transmission routes for SARS-CoV-2, we developed a modeling framework and leveraged detailed information available from the Diamond Princess cruise ship outbreak that occurred in early 2020. We modeled 21,600 scenarios to generate a matrix of solutions across a full range of assumptions for eight unknown or uncertain epidemic and mechanistic transmission factors. A total of 132 model iterations met acceptability criteria (R2 > 0.95 for modeled vs. reported cumulative daily cases and R2 > 0 for daily cases). Analyzing only these successful model iterations quantifies the likely contributions of each defined mode of transmission. Mean estimates of the contributions of short-range, long-range, and fomite transmission modes to infected cases across the entire simulation period were 35%, 35%, and 30%, respectively. Mean estimates of the contributions of larger respiratory droplets and smaller respiratory aerosols were 41% and 59%, respectively. Our results demonstrate that aerosol inhalation was likely the dominant contributor to COVID-19 transmission among the passengers, even considering a conservative assumption of high ventilation rates and no air recirculation conditions for the cruise ship. Moreover, close-range and long-range transmission likely contributed similarly to disease progression aboard the ship, with fomite transmission playing a smaller role. The passenger quarantine also affected the importance of each mode, demonstrating the impacts of the interventions.

Co-circulation of SARS-CoV-2 and Influenza under vaccination scenarios

The interaction and possibly interference between viruses infecting a common host population is the problem addressed in this work. We model two viral diseases both of the SIRS type that have similar mechanism of transmission and for which a vaccine exists. The vaccine is characterized by its coverage, induced temporal immunity and efficacy. The population dynamics of both diseases considers infected individuals of each disease and hosts that are susceptible to one but have recovered from the other. We do not incorporate coinfection. We postulate two main transmission factors affecting the effective contact rates: i) that the virus with higher reproduction number can superinfect the one with lower reproduction number and ii) that there is some protection induced by vaccination against the weaker virus that reduces the probability of infection by the stronger virus. Our results indicate that coexistence of the viruses is possible in the long term. The time-dependent effective contact rate may induce either alternating outbreaks of each disease or synchronous outbreaks. We also found the existence of bi-stability triggered by a backward bifurcation, conducive to scenarios where, at the population level, vaccine application may promote persistence of both diseases provided the effective coverage and vaccine efficacy are low.