Potential Use of Tea Tree Oil as a Disinfectant Agent against Coronaviruses: A Combined Experimental and Simulation Study

The COVID-19 pandemic has highlighted the relevance of proper disinfection procedures and renewed interest in developing novel disinfectant materials as a preventive strategy to limit SARS-CoV-2 contamination. Given its widely known antibacterial, antifungal, and antiviral properties, Melaleuca alternifolia essential oil, also named Tea tree oil (TTO), is recognized as a potential effective and safe natural disinfectant agent. In particular, the proposed antiviral activity of TTO involves the inhibition of viral entry and fusion, interfering with the structural dynamics of the membrane and with the protein envelope components. In this study, for the first time, we demonstrated the virucidal effects of TTO against the feline coronavirus (FCoVII) and the human coronavirus OC43 (HCoV-OC43), both used as surrogate models for SARS-CoV-2. Then, to atomistically uncover the possible effects exerted by TTO compounds on the outer surface of the SARS-CoV-2 virion, we performed Gaussian accelerated Molecular Dynamics simulations of a SARS-CoV-2 envelope portion, including a complete model of the Spike glycoprotein in the absence or presence of the three main TTO compounds (terpinen-4-ol, γ-terpinene, and 1,8-cineole). The obtained results allowed us to hypothesize the mechanism of action of TTO and its possible use as an anti-coronavirus disinfectant agent.     

On Integral Graphs which Belong to the Class $\overline {\alpha K_{a,a,a}\cup \beta K_{b,b,b}}$

Let $G$ be a simple graph and let $\overline G$ denote its complement. We say that $G$ is integral if its spectrum consists entirely of integers. In this work we establish a characterization of integral graphs which belong to the class $\overline {\alpha K_{a,a,a} \cup\beta K_{b,b,b}}$, where $mG$ denotes the $m$-fold union of the graph $G$.     

Further Improvements in High Gain Observer Design for Systems with Structured Nonlinearities

Due to their simple implementation based on a constant gain matrix, high gain observers are very common in practical applications. We consider systems whose dynamics can be decomposed into a linear and a nonlinear part, where the nonlinear part meets some Lipschitz condition. In many cases there exists a finite bound on the maximum feasible Lipschitz constant for which the error dynamics can be stabilized. Necessary and in some sense sufficient conditions for this maximum Lipschitz constant are given in [1]. These results has been improved in [2,3] by taking the structure of the linear part into account. Having a system with one single nonlinearity, the results given in [2,3] are strict. If multiple nonlinearities occur, even this approach tends to be to conservative. In this case, one could additionally take the internal structure of the nonlinearities into account which leads to a larger set of systems for which convergence of the observer error can be guaranteed. Our new approach is based on an approximation of the structured singular value [4] which yields existence conditions in terms of linear matrix inequalities (LMIs). These LMIs may as well be used for the numerical computation of the observer gain. We demonstrate the advantage of our method on an example. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

CFD modelling of a spray deposition process of paint

The paint deposition process by spraying has been studied by means of Computational Fluid Dynamics in order to predict the final thickness of the coating and to determine theoretically the overspraying phenomenon. The VOF model has been used to describe the impact phenomena onto the wall and the Euler-Lagrange approach to simulate droplet trajectories on their way to the surface. Particular attention has been devoted to the prediction of the maximum diameter reached by an impinging droplet at the end of the spreading phase. This diameter is very important in the study of the paint processes because the high viscosity and the small surface tension of paints reduce the impingement practically only to the spreading phase. Two different configurations of atomizers have been considered. The air flux provides a finer atomisation of the liquid, gives to the droplets the necessary velocity to reach the wall, but is also the main cause of overspray since the small droplets tend to follow its deviation near the wall.     

Novel initiators for oxazoline polymerization: generation of polydiacetylene-polyoxazoline networks

A series of bolaform polyoxazolines (POZO) with 1,3-diacetylene cores ((POZO)_m-(CH₂)_n-C≡C-C≡C-(CH₂)_n-(POZO)_m) were synthesized by the living polymerization of 2-methyl-1,3-oxazolines initiated by triflate esters derived from bis(ω-hydroxyalkyl)-1,3-diacetylenes. The chain length of the alkylspacers within the diacetylene core as well as the length of the attached polyoxazoline chains was varied between n = 1 and 4; m = 5, 10 and 15. The thermally induced 1,4-addition process yielding polydiacetylenes (PDA) was studied leading to highly conjugated POZO-PDA hybrid materials.     

Nanocomposite‐based stretchable optics

Stretchable and conformable optical devices open up very exciting perspectives for the fabrication of systems incorporating diffracting and optical power in a single element. Supersonic cluster beam implantation of silver nanoparticles in an elastomeric substrate grooved by molding allows effective fabrication of cheap and simple stretchable optical elements able to withstand thousands of deformations and stretching cycles without any degradation of their optical properties. The nanocomposite‐based reflective optical devices were characterized both morphologically and optically showing excellent performances and stability compared to similar devices fabricated with standard techniques. The nanocomposite‐based devices can therefore be applied to arbitrary curved nonoptical grade surfaces in order to achieve optical power and to minimize aberrations like astigmatism. The high resilience of the nanocomposite material on which the devices are based allows them to be peeled and reused multiple times.