Mathematical Modeling and Analysis of the Dynamics of RNA Viruses in Presence of Immunity and Treatment: A Case Study of SARS-CoV-2.

The emergence of novel RNA viruses like SARS-CoV-2 poses a greater threat to human health. Thus, the main objective of this article is to develop a new mathematical model with a view to better understand the evolutionary behavior of such viruses inside the human body and to determine control strategies to deal with this type of threat. The developed model takes into account two modes of transmission and both classes of infected cells that are latently infected cells and actively infected cells that produce virus particles. The cure of infected cells in latent period as well as the lytic and non-lytic immune response are considered into the model. We first show that the developed model is well-posed from the biological point of view by proving the non-negativity and boundedness of model's solutions. Our analytical results show that the dynamical behavior of the model is fully determined by two threshold parameters one for viral infection and the other for humoral immunity. The effect of antiviral treatment is also investigated. Furthermore, numerical simulations are presented in order to illustrate our analytical results.

Spirulina platensis extract improves the production and defenses of the common bean grown in a heavy metals-contaminated saline soil.

Plants have to cope with several abiotic stresses, including salinity and heavy metals (HMs). Under these stresses, several extracts have been used as effective natural biostimulants, however, the use of Spirulina platensis (SP) extract (SPE) remains elusive. The effects of SPE were evaluated as soil addition (SA) and/or foliar spraying (FS) on antioxidant defenses and HMs content of common bean grown in saline soil contaminated with HMs. Individual (40 or 80 mg SPE/hill added as SA or 20 or 40 mg SPE/plant added as FS) or integrative (SA+FS) applications of SPE showed significant improvements in the following order: SA-80+FS-40 > SA-80+FS-20 > SA-40+FS-40 > SA-40+FS-20 > SA-80 > SA-40 > FS-40 > FS-20 > control. Therefore, the integrative SA+FS with 40 mg SP/plant was the most effective treatment in increasing plant growth and production, overcoming stress effects and minimizing contamination of the edible part. It significantly increased plant growth (74%-185%) and yield (107%-227%) by enhancing net photosynthetic rate (78.5%), stomatal conductance (104%), transpiration rate (124%), and contents of carotenoids (60.0%), chlorophylls (49%-51%), and NPK (271%-366%). These results were concurrent with the marked reductions in malondialdehyde (61.6%), hydrogen peroxide (42.2%), nickel (91%-94%), lead (80%-9%), and cadmium (74%-91%) contents due to the improved contents of glutathione (87.1%), ascorbate (37.0%), and α-tocopherol (77.2%), and the activities of catalase (18.1%), ascorbate peroxidase (18.3%), superoxide dismutase (192%), and glutathione reductase (52.2%) as reinforcing mechanisms. Therefore, this most effective treatment is recommended to mitigate the stress effects of salinity and HMs on common bean production while minimizing HMs in the edible part.

Refractory plasmonics enabling 20% efficient lead-free perovskite solar cells.

Core-shell refractory plasmonic nanoparticles are used as excellent nanoantennas to improve the efficiency of lead-free perovskite solar cells (PSCs). SiO2 is used as the shell coating due to its high refractive index and low extinction coefficient, enabling the control over the sunlight directivity. An optoelectronic model is developed using 3D finite element method (FEM) as implemented in COMSOL Multiphysics to calculate the optical and electrical parameters of plain and ZrN/SiO2-modified PSCs. For a fair comparison, ZrN-decorated PSCs are also simulated. While the decoration with ZrN nanoparticles boosts the power conversion efficiency (PCE) of the PSC from 12.9% to 17%, the use of ZrN/SiO2 core/shell nanoparticles shows an unprecedented enhancement in the PCE to reach 20%. The enhancement in the PCE is discussed in details.

Technique and outcome of autotransplanting thyroid tissue after total thyroidectomy for simple multinodular goiters.

BACKGROUND/OBJECTIVE: Limited animal and human studies have shown function, albeit inadequate, of implanted thyroid tissue in muscles. This work aimed to ascertain results in a larger number of patients, finding practical method for implantation, studying the effect of changing weight of implant and effect of passage of time on its function. METHODS: Forty patients had total thyroidectomy for simple multinodular goiters. A piece of the excised gland was finely minced, mixed with saline as emulsion, and injected in thigh muscles. Twelve patients had 5-g implants, while 28 patients had 10-g implants. Four parameters were studied at 2 months, 6 months, and 12 months: technetium isotope uptake by the implant; thyroid stimulating hormone (TSH); free T3 (FT3); and free T4 (FT4). RESULTS: All autotransplanted thyroid tissue survived and functioned. After 12 months, mean values (± standard deviation) of isotope uptake, TSH, FT3, and FT4 of the 5-g implants were 0.44 ± 0.16%, 27.74 ± 30.4 UI/mL, 3.07 ± 1.10 pg/mL, and 1.01 ± 0.3 ng/dL, repectively. Those for the 10 g implants were 0.71 ± 0.20%, 22.78 ± 19.7 UI/mL, 3.92 ± 1.2 pg/mL, and 1.05 ± 0.3 ng/dL, repectively. Ten-gram implants showed significantly higher isotope uptake than 5-g. TSH, FT3, and FT4 significantly improved over the period of 1 year. CONCLUSION: Injection of thyroid tissue suspension is a simple method for thyroid autotransplantation. TSH was elevated in the majority to maintain normal or near normal thyroid hormones. Ten-gram implants showed higher isotope uptake than 5-g, although this difference was not reflected by thyroid hormone profile. The implant seemed to function better with the passage of time from 2 months to 12 months.