Analysis of a stochastic distributed delay epidemic model with relapse and Gamma distribution kernel

In this work, we investigate a stochastic epidemic model with relapse and distributed delay. First, we prove that our model possesses and unique global positive solution. Next, by means of the Lyapunov method, we determine some sufficient criteria for the extinction of the disease and its persistence. In addition, we establish the existence of a unique stationary distribution to our model. Finally, we provide some numerical simulations for the stochastic model to assist and show the applicability and efficiency of our results.Ministerio de Ciencia, Innovación y Universidades (MICINN). EspañaEuropean Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER

Dynamics of a stochastic coronavirus (COVID-19) epidemic model with Markovian switching

In this paper, we analyze a stochastic coronavirus (COVID-19) epidemic model which is perturbed by both white noise and telegraph noise incorporating general incidence rate. Firstly, we investigate the existence and uniqueness of a global positive solution. Then, we establish the stochastic threshold for the extinction and the persistence of the disease. The data from Indian states, are used to confirm the results established along this paper

Analysis of a stochastic coronavirus (COVID-19) L´evy jump model with protective measures

This paper studied a stochastic epidemic model of the spread of the novel coronavirus (COVID19). Severe factors impacting the disease transmission are presented by white noise and compensated poisson noise with possibly infinite characteristic measure. Large time estimates are established based on Kunita’s inequality rather than Burkholder-Davis-Gundy inequality for countinuous diffusions. The effect of stochasticity is taken into account in the formulation of sufficient conditions for the extinction of COVID-19 and its persistence. Our results prove that environmental fluctuations can be privileged in controlling the pandemic behaviour. Based on real parameter values, numerical results are presented to illustrate obtained results concerning the extinction and the persistence in mean of the disease

Electronic and optical properties of CeO 2 from first principles calculations

International audienceFirst-principles calculations of the electronic structure of CeO2 nanoparticles (NPs) were performed to investigate published experimental data obtained by different spectroscopies. The main features of the valence and conduction bands have been analyzed from the total and partial density of states. Several functionals were applied to interpret and quantify the optical properties, including the dielectric function, extinction coefficient and refractive index. It is found that the on-site hybrid functional B3PW91 modelled most suitably the band gap region of CeO2 NPs and consequently gave a more accurate band gap value. It also agreed very well with the experimental values especially in the visible-ultraviolet optical range

Theoretical study of the interaction between carbon nanotubes and carboplatin anticancer molecules

International audienceFull DFT calculations were carried out to study the interactions between single-wall functionalized carbon-based metallic nanotubes (CNTs) and carboplatin anticancer drugs. The geometry of the CNT-carboplatin was optimized considering different molecular configurations on inner and outer surfaces of the nanotubes. Simulation results show that the most stable physisorption state for molecules is to be located inside the nanotubes in a parallel configuration. Furthermore{,} we demonstrated that the molecular physisorption was reinforced as soon as the number of encapsulated carboplatin molecules increased{,} leading to a favored state where the nanovector is filled by the drug. Moreover{,} all theoretical results show that the therapeutic agent is not affected when it is attached onto CNT

Theoretical Demonstration of the Potentiality of Boron Nitride Nanotubes to Encapsulate Anticancer Molecule

International audienceAnticancer drug transport is now becoming an important scientific challenge since it would allow localizing the drug release near the tumor cell, avoiding secondary medical effects. We present theoretical results, based on density functional theory and molecular dynamics simulations, which demonstrate the stability of functionalized single (10,10) boron nitride nanotubes (BNNTs) filled with anticancer molecule such as carboplatin (CPT). For this functionalized system we determine the dependence of the adsorption energy on the molecule displacement near the inner BNNTs surface, together with their local morphological and electrical changes and compare the values to the adsorption energy obtained on the outer surface. Quantum simulations show that the most stable physisorption state is located inside the nanotube, with no net charge transfer. This demonstrates that chemotherapeutic encapsulation is the most favorable way to transport drug molecules. The solvent effect and dispersion repulsion contributions are then taken into account using molecular dynamics simulations. Our results confirm that carboplatin therapeutic agents are not affected when they are adsorbed inside BNNTs by the surrounding water molecules