1,722,083 research outputs found
Natalizumab safety in paediatric-onset multiple sclerosis at the time of SARS-Cov-2 pandemic
No full textMode coupling behavior and fragile to strong transition of trehalose in a binary mixture with water upon supercooling
No full textWe perform molecular dynamics simulations of a binary mixture of water and trehalose with the TIP4P/Ice water model. We analyze the slow dynamics of trehalose molecules in the mildly supercooled region for concentrations of 3.66 and 18.57 wt. %. We previously studied the dynamics of water in the same mixtures. Supercooled TIP4P/Ice water solvating trehalose molecules was found to follow the Mode Coupling Theory (MCT) and to undergo a transition from a fragile to a strong behavior for both concentrations. Here, we show that also the dynamics of trehalose molecules follows the MCT and displays a fragile to strong crossover (FSC). The results show that trehalose in binary mixtures with water shares with it the dynamical behavior typical of glass forming liquids. Moreover, the FSC for trehalose structural relaxation times is found to occur at temperatures close to those previously obtained for water in the same solutions, showing that the dynamics of the solute is strongly coupled to that of the solvent. We also perform a MCT test showing that the trehalose dynamics obeys the MCT time-temperature superposition principle and that the exponents derived from the theory and the ones obtained from fitting procedure of the relaxation times are comparable, confirming that trehalose molecules in supercooled water solutions follow the MCT of glassy dynamics. Moreover, as predicted by the theory, trehalose particles have MCT parameters comparable to those of water in the same mixtures. This is an important result, given that MCT was originally formulated for monoatomic particles
Thermodynamics, phase diagram, structure and anomalies of supercooled aqueous solutions of trehalose: A molecular dynamics study
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The role of repeat endoscopic third ventriculostomy after failure of the initial procedure.
No full text[no abstract available
Structural properties and liquid spinodal of water confined in a hydrophobic environment
No full textWe present the results of a computer simulation study of thermodynamical properties of TIP4P water confined in a hydrophobic disordered matrix of soft spheres upon supercooling. The hydrogen-bond network of water appears preserved in this hydrophobic confinement. Nonetheless a reduction in the average number of hydrogen bonds due to the geometrical constraints is observed. The liquid branch of the spinodal line is calculated from 350 K down to 210 K. The same thermodynamic scenario of the bulk is found: the spinodal curve is monotonically decreasing. The line of maximum density bends avoiding a crossing of the spinodal. There is, however, a shift both of the line of maximum density and of the spinodal toward higher pressures and lower temperatures with respect to bulk
Phase Diagram of Aqueous Solutions of LiCl: a Study of Concentration Effects on the Anomalies of Water
No full textWe perform molecular dynamics simulationsin order tostudy thermodynamicsand the structure of supercooled aqueous solutions of lithium chloride(LiCl) at concentrations c = 0.678 and 2.034 mol/kg.We model the solvent using the TIP4P/2005 potential and the ions usingthe Madrid-2019 force field, a force field particularly suited forstudying this solution. We find that, for c = 0.678mol/kg, the behavior of the equation of state, studied in the P-T plane, indicates the presenceof a liquid-liquid phase transition, similar to what was previouslyfound for bulk water. We estimate the position of the liquid-liquidcritical point to be at T (c) approximate to 174K, P (c) approximate to 1775 bar, and rho(c) approximate to 1.065 g/cm(3). When the concentration istripled to c = 2.034 mol/kg, no critical point isobserved, indicating its possible disappearance at this concentration.We also study the water-water and water-ions structurein the two solutions, and we find that at the concentrations examinedthe effect of ions on the water-water structure is not strong,and all the features found in bulk water are preserved. We also calculatethe hydration number of the Li and Cl ions, and in line with experiments,we find the value of 4 for Li+ and between 5.5 and 6 forCl(-), confirming the good performances of the Madrid-2019force field
Il paradigma Progetto e Norma: ricerca di qualità nel progetto di architettura. The Project and Regulation paradigm: the search for quality in architectural design
No full textOver the last few decades, the complexity aggravated by transformations taking place in the social, economic, technological and environmental context has undoubtedly produced inevitable effects on the Project and Regulation binomial, with a consequent increase in compulsory and voluntary regulatory apparatuses to support design action in the building process involving a multiplicity of actors and specialised knowledge. It is a composite regulatory landscape relating to the regulation of quality in architecture, the result of interweaving and interaction between multiple sources of Euro-Community origin, progressively transposed at national level.In view of these considerations, it is essential to rethink a renewed balance between prescription and consensus, direction and control, in order to guide the project towards quality works at different scales in the awareness that the regulation alone does not have the requisites to ensure that the construction can cope with the discomfort we feel towards the environment we live in. This does not mean that design activities should be freed from regulatory (i.e. operational) references, but only that they must be understood within the cultural awareness of constructing.La complessità, aggravata dalle trasformazioni del contesto sociale, economico, tecnologico e ambientale ha indubbiamente prodotto nel corso degli ultimi decenni, effetti inevitabili sul binomio Progetto e Norma, con un conseguente aumento di apparati regolamentari cogenti e volontari a supporto dell’azione progettuale nel processo edilizio facenti capo a una molteplicità di attori e saperi specialistici. Un panorama normativo composito, relativo alla regolamentazione della qualità in architettura, frutto dell’intreccio e dell’interazione tra una molteplicità di fonti di matrice euro-comunitaria, progressivamente recepite a livello nazionale. A fronte di tali considerazioni è indispensabile ripensare a un rinnovato equilibrio tra prescrizione e consenso, indirizzo e controllo, per orientare il progetto alla qualità degli interventi alle diverse scale nella consapevolezza che da sola la norma non possiede i requisiti per assicurare un costruito che faccia fronte al disagio che si prova nei confronti dell’ambiente che abitiamo. Questo non significa liberare l’attività progettuale dai riferimenti normativi (cioé operativi) ma solo che questi devono essere colti all’interno della consapevolezza culturale del costruire
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