F. Mercuri
Instituto Politécnico Nacional
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Publication
Featured researches published by F. Mercuri.
Journal of Chemical Physics | 2016
S. Paoloni; F. Mercuri; U. Zammit
In this work we use a photopyroelectric calorimetric set up to analyze the transformations occurring in thin samples of liquid crystal-microemulsion system by combining the results of the simultaneously performed high temperature resolution polarization microscopy observations and the temperature dependence of the specific heat, and of the thermal conductivity. This enabled an accurate direct correlation of the observations concerning the different measured quantities for a most comprehensive interpretation of the obtained results. It is found that the I-N conversion progresses in the entire nematic range because of the micelles expelled from the nucleating nematic volumes remaining confined in the residual isotropic material. A hysteretic behavior is observed in the nematic range between cooling and heating run because of the different micelle content in the material during the cooling and heating runs. A moderate hysteresys also over the N-A transition indicated an additional material refinement from micelles during the transition. Finally in samples with different micelle concentration the same maximum micelle content is retained in the nematic and smectic phases.
Journal of Chemical Physics | 2013
F. Mercuri; S. Paoloni; M. Marinelli; R. Pizzoferrato; U. Zammit
The smecticA-hexaticB phase transition was studied in a homeotropic single domain sample and in a non-aligned sample of n-hexyl-4-n-pentyloxybiphenyl-4-carboxylate liquid crystal compound to probe the effect of different amount of defects on the phase transition. The specific heat, the thermal diffusivity and the enthalpy exchange were monitored over the transition and, at the same time, polarization microscopy observations could be carried out. The transition during the first cooling run was found to be accompanied by a considerably larger defect annealing in the non-aligned sample than in the homeotropic one, but the critical behaviour of the specific heat remained substantially the same.
Journal of Chemical Physics | 2015
S. Paoloni; F. Mercuri; M. Marinelli; R. Pizzoferrato; U. Zammit; T. Kosa; L. Sukhomlinova; B. Taheri
We have studied the specific heat and the thermal conductivity in a 4-(n-octyl)-4-cyanobiphenyl liquid crystal (LC)-photochromic molecules mixture, before, during, and after the photo-activation of the dispersed photochromic molecules, over both the smectic A-nematic and the nematic-isotropic phase transitions. The evaluation of the specific heat has enabled the determination of the changes of the phase transition characteristics induced by the photochromic molecules photoisomerization, while that of the thermal conductivity could be used to monitor the modifications induced in the average LC molecular orientation. The polarization microscopy imaging of the sample texture constituted a valuable support for the interpretation of the obtained thermal conductivity results.
Journal of Chemical Physics | 2018
S. Paoloni; F. Mercuri; U. Zammit
In the present work, by means of the photopyroelectric calorimetric investigations in liquid crystal/naphtopyran (NP) molecule mixtures, the effect of the photoisomerization of NP by UV light on the critical behavior of specific heat could be studied over the smectic-nematic phase transition. It is shown that the UV light irradiation of the sample can shift the critical exponent from a non-universal value typical of the non-irradiated mixture to one close to that of the 3D-XY universality class, predicted for such a transition. This witnesses the optically triggered reduction of the coupling between the smectic and nematic order parameters responsible for the deviation from the XY-like behavior. A tentative explanation is provided based on the weakening of the order parameter coupling caused by the NP molecules entering the smectic layers following the UV light illumination.
Journal of Archaeological Science: Reports | 2017
F. Mercuri; Noemi Orazi; U. Zammit; Augusto Giuffredi; Carlo Stefano Salerno; Cristina Cicero; S. Paoloni
Journal of Cultural Heritage | 2017
F. Mercuri; Paolo Buonora; Cristina Cicero; Philine Helas; Francesca Manzari; M. Marinelli; S. Paoloni; Alessandra Pasqualucci; Flavia Pinzari; Martina Romani; Alessandra Terrei; Orietta Verdi; Gianluca Verona Rinati; U. Zammit; Noemi Orazi
Infrared Physics & Technology | 2018
F. Mercuri; G. Caruso; Noemi Orazi; U. Zammit; Cristina Cicero; O. Colacicchi Alessandri; M. Ferretti; S. Paoloni
Proceedings of the 2018 International Conference on Quantitative InfraRed Thermography | 2018
G. Caruso; F. Mercuri; S. Paoloni; Noemi Orazi; U. Zammit; Cristina Cicero; M. Ferretti; O. Colacicchi Alessandri
International Journal of Thermophysics | 2018
U. Zammit; F. Mercuri; S. Paoloni; R. Pizzoferrato
International Journal of Thermophysics | 2018
Noemi Orazi; S. Paoloni; U. Zammit; Cristina Cicero; M. Ferretti; G. Caruso; O. Colacicchi Alessandri; R. Paris; F. Mercuri