Coronavirus Disinfection Physical Methods

Since 2019, the spread of the Coronavirus pandemic becomes the global health crisis. To fight the pandemic, several measures were adopted such as: Hygiene measure, massive test, social distancing, quarantine and distancing. Disinfection is an important operation in the fight against the spread of Corona virus pandemic. The disinfection methods are of chemical and physical type. In this work, we focused our interest to the physical methods. These methods are classified in three principal categories: irradiation techniques, heat treatment and mechanical techniques. All the different aspect of techniques are exposed in this chapter. The efficiency of the used techniques is also discussed

Propagation Analysis of the Coronavirus Pandemic on the Light of the Percolation Theory

Efforts to combat the Covid-19 pandemic have not been limited to the processes of vaccine production, but they first began to analyze the dynamics of the epidemic’s spread so that they could adopt barrier measures to bypass the spread. To do this, the works of modeling, predicting and analyzing the spread of the virus continue to increase day after day. In this context, the aim of this chapter is to analyze the propagation of the Coronavirus pandemic by using the percolation theory. In fact, an analogy was established between the electrical conductivity of reverse micelles under temperature variation and the spread of the Coronavirus pandemic. So, the percolation theory was used to describe the cumulate infected people versus time by using a modified Sigmoid Boltzman equation (MSBE) and several quantities are introduced such as: the pandemic percolation time, the maximum infected people, the time constant and the characteristic contamination frequency deduced from Arrhenius equation. Scaling laws and critical exponents are introduced to describe the spread nature near the percolation time. The speed of propagation is also proposed and expressed. The novel approach based on the percolation theory was used to study the Coronavirus (Covid-19) spread in five countries: France, Italy, Germany, China and Tunisia, during 6 months of the pandemic spread (the first wave). So, an explicit expression connecting the number of people infected versus time is proposed to analyze the pandemic percolation. The reported MSBE fit results for the studied countries showed high accuracy

A structural study of a polymer-surfactant system in dilute and entangled regime: Effect of high concentrations of surfactant and polymer molecular weight

International audienceIn the polymer-surfactant system, increasing the concentration of surfactant leads to structural changes in surfactant micelles. This is expected to influence the polymer conformation in the dilute regime where polymer chains are singles and in the entangled regime where the polymer system is described by the blob concept. In this report, the effect of large Sodium bis(2-ethylhexyl) sulfosuccinate (AOT), surfactant concentrations on the conformation of two polyvinylpyrrolidone (PVP) molecular weight (M w ¼ 55000 g/ mol and M w ¼ 360000 g/mol) was discussed. In the first part, in the dilute regime, C PVP 3C*where polymer chains are considered isolated, the determination of PVP (M w ¼ 55000 g/mol and M w ¼ 360000 g/mol) intrinsic viscosity ½h showed a coil to globule transition with the increase of temperature. Electrical conductivity measurements have shown the morphological transition (sphere-cylinder) of surfactant micelles with the increase of surfactant concentrations. The addition of AOT wormlike micelles revealed the expansion of PVP chains for the two molecular weight. In the second part, in PVP entangled regime,C PVP x16C* where overlapped polymer chains form molecular blobs, the addition of AOT wormlike micelles to PVP solutions doesn't affect the Newtonian behavior of PVP (M w ¼ 55000) and the pseudo-plastic behavior of PVP (M w ¼ 360000 g/mol). However, AOT surfactant reinforces significantly the dynamic viscosity of PVP,h for the two molecular weight. By fitting the PVP viscosity-temperature dependence with Fulcher-Tammann-Vogel law, the results showed that the more the surfactant is added, the stronger the PVP solution becomes, which proves that AOT cylindrical (wormlike) micelles presence enhances the solid character of PVP solutions