Novel hybrid systems based on poly(propylene-g-maleic anhydride) and Ti-POSS by direct reactive blending

Novel hybrid systems based on maleic anhydride-grafted polypropylene (PPgMA) and home-made Ti-containing amino polyhedral oligomeric silsesquioxanes (Ti-POSS-NH₂) have been prepared by one-step reactive blending, and their properties have been compared with those of systems based on a non-reactive POSS (POSS). The occurrence of a reaction between PPgMA and the reactive POSS molecules has been assessed by Fourier Transform Infrared Resonance (FTIR) measurements, whereas dispersion of POSS into the polymer was evaluated by Scanning Electron Microscopy (SEM), showing a nanometric dispersion only for the reactive POSS. Thermo-oxidative behaviour was studied by Thermogravimetric Analysis (TGA), showing a delayed volatilization of the PPgMA/Ti-POSS-NH₂ with respect to both PPgMA/POSS and pristine PPgMA, which is attributed to the chemical activity of Ti in Ti-POSS-NH₂. To highlight the mechanism of the hybrid system decomposition, samples which underwent a thermal treatment at 250 °C, i.e. the onset temperature for polymer matrix decomposition in thermo-oxidative conditions, have been studied by FTIR and X-Ray Photoelectron Spectroscopy (XPS) measurements.     

Formation of aluminium, aluminium nitride and nitrogen clusters via laser ablation of nano aluminium nitride. Laser Desorption Ionisation and Matrix-Assisted Laser Desorption Ionisation Time-of-Flight Mass Spectrometry

Laser Desorption Ionisation (LDI) and Matrix-Assisted Laser Desorption Ionisation (MALDI) Time-of-Flight Mass Spectrometry (TOFMS) were used to study the pulsed laser ablation of aluminium nitride (AlN) nano powder. The formation of Al(m)(+) (m=1-3), N(n)(+) (n=4, 5), AlN(n)(+) (n=1-5, 19, 21), Al(m)N(+) (m=2-3), Al(3)N(2)(+), Al(9)N(n)(+) (n=5, 7, 9, 11 and 15), Al(11)N(n)(+) (n=4, 6, 10, 12, 19, 21, 23, and 25), and Al(13)N(n)(+) (n=25, 31, 32, 33, 34, 35, and 36) clusters was detected in positive ion mode. Similarly, Al(m)(-) (m=1-3), AlN(n)(-) (n=1-3, 5), Al(m)N(-) (n=2, 3), Al(2)N(n)(-) (n=2-4, 28, 30), N(n)(-) (n=2, 3), Al(4)N(7)(-) Al(8)N(n)(-) (n=1-6), and Al(13)N(n)(-) (n=9, 18, 20, 22, 24, 26, 28, 33, 35, 37, 39, 41 and 43) clusters were observed in negative ion mode. The formation of the stoichiometric Al(10) N(10) cluster was shown to be of low abundance. On the contrary, the laser ablation of nano-AlN led mainly to the formation of nitrogen-rich Al(m)N(n) clusters in both negative and positive ion mode. The stoichiometry of the Al(m)N(n) clusters was determined via isotopic envelope analysis and computer modelling.     

Continuous EEG-fMRI in patients with partial epilepsy and focal interictal slow-wave discharges on EEG

Purpose

To verify whether in patients with partial epilepsy and routine electroenecephalogram (EEG) showing focal interictal slow-wave discharges without spikes combined EEG–functional magnetic resonance imaging (fMRI) would localize the corresponding epileptogenic focus, thus providing reliable information on the epileptic source.

Methods

Eight patients with partial epileptic seizures whose routine scalp EEG recordings on presentation showed focal interictal slow-wave activity underwent EEG–fMRI. EEG data were continuously recorded for 24 min (four concatenated sessions) from 18 scalp electrodes, while fMRI scans were simultaneously acquired with a 1.5-Tesla magnetic resonance imaging (MRI) scanner. After recording sessions and MRI artefact removal, EEG data were analyzed offline. We compared blood oxygen level-dependent (BOLD) signal changes on fMRI with EEG recordings obtained at rest and during activation (with and without focal interictal slow-wave discharges).

Results

In all patients, when the EEG tracing showed the onset of focal slow-wave discharges on a few lateralized electrodes, BOLD-fMRI activation in the corresponding brain area significantly increased. We detected significant concordance between focal EEG interictal slow-wave discharges and focal BOLD activation on fMRI. In patients with lesional epilepsy, the epileptogenic area corresponded to the sites of increased focal BOLD signal.

Conclusions

Even in patients with partial epilepsy whose standard EEGs show focal interictal slow-wave discharges without spikes, EEG–fMRI can visualize related focal BOLD activation thus providing useful information for pre-surgical planning.     

Photoluminescent decoration of iron oxide magnetic nanoparticles for dual-imaging applications

A selective functionalization of dopamine amino group with the photoluminescent 7-nitroben-zofurazan was achieved through a one-pot protection-functionalization-deprotection sequence. The resulting fluorescent catecholic ligand was used as a capping agent for iron oxide nanoparticles thus obtaining photoluminescent magnetic nanoparticles (PL-MNPs). The PL-MNPs were then embedded into PLGA-b-PEG polymeric nanocarriers which quenched the emission of the capping agent. Full recovery of fluorescence was observed after disassembling the polymeric layer of the nanoparticle, thus supporting the use of PL-MNPs as a multifunctional system for targeted drug delivery.     

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 $G$.     

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.     

Ferrous to Ferric Transition in Fe-Phthalocyanine Driven by NO2 Exposure

Due to its unique magnetic properties offered by the open-shell electronic structure of the central metal ion, and for being an effective catalyst in a wide variety of reactions, iron phthalocyanine has drawn significant interest from the scientific community. Nevertheless, upon surface deposition, the magnetic properties of the molecular layer can be significantly affected by the coupling occurring at the interface, and the more reactive the surface, the stronger is the impact on the spin state. Here, we show that on Cu(100), indeed, the strong hybridization between the Fe d-states of FePc and the sp-band of the copper substrate modifies the charge distribution in the molecule, significantly influencing the magnetic properties of the iron ion. The Fe^II ion is stabilized in the low singlet spin state (S=0), leading to the complete quenching of the molecule magnetic moment. By exploiting the FePc/Cu(100) interface, we demonstrate that NO₂ dissociation can be used to gradually change the magnetic properties of the iron ion, by trimming the gas dosage. For lower doses, the FePc film is decoupled from the copper substrate, restoring the gas phase triplet spin state (S=1). A higher dose induces the transition from ferrous to ferric phthalocyanine, in its intermediate spin state, with enhanced magnetic moment due to the interaction with the atomic ligands. Remarkably, in this way, three different spin configurations have been observed within the same metalorganic/metal interface by exposing it to different doses of NO₂ at room temperature.     

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.