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177 results on '"Ciuchi, F."'

1. Enhanced X-ray-phase-contrast-tomography brings new clarity to the 2000-year-old 'voice' of Epicurean philosopher Philodemus

Author

Bukreeva, I., Mittone, A., Bravin, A., Festa, G., Alessandrelli, M., Coan, P., Formoso, V., Agostino, R. G., Giocondo, M., Ciuchi, F., Fratini, M., Massimi, L., Lamarra, A., Andreani, C., Bartolino, R., Gigli, G., Ranocchia, G., and Cedola, A.

Subjects
Physics - Physics and Society
Abstract

A collection of more than 1800 carbonized Greek and Latin papyri, discovered in the Roman Villa dei Papiri at Herculaneum in the middle of 18th century, is the unique classical library survived from antiquity. These ancient-Herculaneum-papyri were charred during 79 A.D. Vesuvius eruption, a circumstance which providentially preserved them until now. This magnificent collection contains valuable work by Greek philosophers, such as Epicurus, Chrysippus and Philodemus, in particular an impressive amount of extensive treatises by Philodemus of Gadara, an Epicurean philosopher of the 1st century BC. The aim of the present study is to read extended and hitherto unknown portions of text hidden inside carbonized-Herculaneum-papyri using enhanced X-ray-phase-contrast-tomography (XPCT) non-destructive technique and a new set of numerical algorithms for virtual-unrolling. This paper documents our success in revealing the largest portion of Greek text ever detected so far inside unopened scrolls, with unprecedented spatial resolution and contrast, all without damaging these precious historical manuscripts. Parts of texts have been decoded and the 'voice' of Epicurean philosopher Philodemus is brought back again after 2000 years from rolled-up carbonized Herculaneum-papyri.

Published
2016

2. Modelling dielectric behaviour and anomalous relaxation in chromonic liquid crystals.

Author

Ciuchi, F., de Santo, M. P., Tone, C. M., Evangelista, L. R., Lenzi, E. K., Ribeiro de Almeida, R. R., Rosseto, M. P., and Zola, R. S.

Subjects
*NEMATIC liquid crystals, *BOUNDARY value problems, *LIQUID crystals, *DEBYE length, *LIQUID dielectrics
Abstract

We discuss the feasibility of applying a frequency-dependent diffusive model to study the dielectric response of complex fluids. The model considers the effect of free and bound particles by solving a non-exponential relaxation behaviour and anomalous diffusion phenomena into a coupled system of differential equations and boundary conditions. To illustrate the potentialities of the model in the data interpretation, we used the experimental results that provide the frequency spectra of a system formed by an aqueous solution of sunset yellow, a chromonic liquid crystal. Our model yields a considerably better adjustment of the experimental data compared to the simple Havriliak-Negami model and provides the relaxation frequency due to the director mode associated with the stack fluctuations about their short axis. Furthermore, we obtained parameters associated with the ion motion nature of the sample, including diffusion coefficient, Debye length and the ionic diffusive regime, which present a similar subdiffusive behaviour found in nematic thermotropic liquid crystals. [ABSTRACT FROM AUTHOR]

Published
2024
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11. Virtual unrolling and deciphering of Herculaneum papyri by X-ray phase-contrast tomography

Author

Bukreeva, I, Mittone, A, Bravin, A, Festa, G, Alessandrelli, M, Coan, P, Formoso, V, Agostino, R, Giocondo, M, Ciuchi, F, Fratini, M, Massimi, L, Lamarra, A, Andreani, C, Bartolino, R, Gigli, G, Ranocchia, G, Cedola, A, Bukreeva I, Mittone A, Bravin A, Festa G, Alessandrelli M, Coan P, Formoso V, Agostino R G, Giocondo M, Ciuchi F, Fratini M, Massimi L, Lamarra A, Andreani C, Bartolino R, Gigli G, Ranocchia G, Cedola A, Bukreeva, I, Mittone, A, Bravin, A, Festa, G, Alessandrelli, M, Coan, P, Formoso, V, Agostino, R, Giocondo, M, Ciuchi, F, Fratini, M, Massimi, L, Lamarra, A, Andreani, C, Bartolino, R, Gigli, G, Ranocchia, G, Cedola, A, Bukreeva I, Mittone A, Bravin A, Festa G, Alessandrelli M, Coan P, Formoso V, Agostino R G, Giocondo M, Ciuchi F, Fratini M, Massimi L, Lamarra A, Andreani C, Bartolino R, Gigli G, Ranocchia G, and Cedola A

Abstract

A collection of more than 1800 carbonized papyri, discovered in the Roman 'Villa dei Papiri' at Herculaneum is the unique classical library survived from antiquity. These papyri were charred during 79 A.D. Vesuvius eruption, a circumstance which providentially preserved them until now. This magnificent collection contains an impressive amount of treatises by Greek philosophers and, especially, Philodemus of Gadara, an Epicurean thinker of 1st century BC. We read many portions of text hidden inside carbonized Herculaneum papyri using enhanced X-ray phase-contrast tomography non-destructive technique and a new set of numerical algorithms for 'virtual-unrolling'. Our success lies in revealing the largest portion of Greek text ever detected so far inside unopened scrolls, with unprecedented spatial resolution and contrast, all without damaging these precious historical manuscripts. Parts of text have been decoded and the 'voice' of the Epicurean philosopher Philodemus is brought back again after 2000 years from Herculaneum papyri.

Published
2016

13. Surface treatment and bulk density of ions in nematic liquid crystals.

Author

Alexe-Ionescu, A. L., Barbero, G., Ciuchi, F., Mazzulla, A., and Scaramuzza, N.

Subjects
LIQUID crystals, ANIONS, CATIONS, LINEAR systems, ELECTRODES, POISSON'S equation
Abstract

The frequency dependence of the electrical impedance of a planar nematic sample in the shape of a slab is investigated. The measurements are performed by means of an external voltage of small amplitude (a few tens of millivolts) in such a manner that the liquid crystal behaves as a linear system from the electrical point of view. In this framework, the nematic orientation induced by the external field is absent because the applied voltage is smaller than the critical one for the transition of Freedericksz for the considered geometry. Our measurements indicate that the real part of the impedance presents a large plateau, finishing at the frequency of Debye. Whereas the imaginary part diverges in the low frequency region, indicating that the electrodes of the cell behave as blocking electrodes. From the value of the plateau of the resistance of the cell and from the frequency of Debye, we can conclude that the surface treatment to orient the nematic liquid crystal has a strong influence on the bulk density of ions. The experimental data relevant to the real and imaginary part of the impedance of the cell have been analyzed with a model based on the equations of continuity for the positive and negative ions and on the equation of Poisson for the actual electrical potential across the sample. By assuming that there is only a type of positive and negative ions and that the electrodes are perfectly blocking, except adsorb ions, we show that the agreement between theoretical predictions and experimental data is good. [ABSTRACT FROM AUTHOR]

Published
2009
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14. CO selective oxidation using catalytic zeolite membranes

Author

Medrano, J.A., Garofalo, A., Donato, L., Basile, F., De Santo, M.P., Gallucci, F., Cofone, F., Ciuchi, F., Algieri, C., Medrano, J.A., Garofalo, A., Donato, L., Basile, F., De Santo, M.P., Gallucci, F., Cofone, F., Ciuchi, F., and Algieri, C.

Abstract

Traces of CO in hydrogen rich gas streams poison the anode of proton exchange membrane fuel cells reducing their power output and decreasing the cell life. This paper investigates the CO selective oxidation in simulated reformate gas by using catalytic zeolite membranes. In particular, the CO removal efficiency was explored using catalytic membranes characterized by different permeation properties (prepared using different protocols) and loaded with the catalyst by means of cationic exchange and reduction process. The most promising experimental results are obtained with membranes prepared with small crystals and low concentration of zeolite suspension (during the seeding step) and with a hydrothermal treatment of 90 °C for 24 h. These membranes are characterized by lower permeance and showed interesting catalytic performance in terms of CO reduction and selectivity.

Published
2018

16. Un metodo per indurre l’allineamento dei cristalli liquidi nei dispositivi ottici a cristalli liquidi

Author

DE STEFANO L, GIOCONDO M, MAZZULLA A, CIUCHI F, REA I, RENDINA I., GIARDINA, PAOLA, ARMENANTE, ANNUNZIATA, DE STEFANO, L, Giocondo, M, Giardina, Paola, Armenante, Annunziata, Mazzulla, A, Ciuchi, F, Rea, I, and Rendina, I.

Abstract

La presente invenzione riguarda l’utilizzo di materiale organico nella fabbricazione di dispositivi optoelettronici a cristalli liquidi in grado di indurre l’allineamento desiderato delle molecole del mezzo liquido cristallino. Il materiale organico biologico, in particolare proteine purificate da micro-organismi, è depositato, quale substrato allineante, con tecniche adeguate su materiali di supporto di comune utilizzo nei dispositivi basati sui cristalli liquidi, quali vetro e materiali semiconduttori. L’invenzione descrive inoltre la realizzazione di alcuni dispositivi ottici che utilizzano gli strati molecolari considerati.

Published
2007

17. Erratum: Virtual unrolling and deciphering of Herculaneum papyri by X-ray phase-contrast tomography (Scientific Reports (2016) 6 (27227) DOI: 10.1038/srep27227)

Author

Bukreeva, I, Bukreeva, I, Mittone, A, Bravin, A, Festa, G, Alessandrelli, M, Coan, P, Formoso, V, Agostino, R, Giocondo, M, Ciuchi, F, Fratini, M, Massimi, L, Lamarra, A, Andreani, C, Bartolino, R, Gigli, G, Ranocchia, G, Cedola, A, Agostino, RG, Bukreeva, I, Bukreeva, I, Mittone, A, Bravin, A, Festa, G, Alessandrelli, M, Coan, P, Formoso, V, Agostino, R, Giocondo, M, Ciuchi, F, Fratini, M, Massimi, L, Lamarra, A, Andreani, C, Bartolino, R, Gigli, G, Ranocchia, G, Cedola, A, and Agostino, RG

Abstract

The Acknowledgements section in this Article is incomplete. The authors wish to thank Luigi Nicolais (CNR), Glenn Most (SNS, Pisa), Daniel Koger (Lindsey Wilson College, Kentucky, US), G. Neville Greaves (University of Cambridge, UK) for valuable discussions and revisions of the present study, the ESRF Directorate for having granted the beamtime, the Biblioteca Nazionale 'Vittorio Emanuele III' of Naples, for lending us the samples (in particular, the officers Sofia Maresca and Vincenzo Boni), Eugenio Amendola (CNR-IPCB), for valuable assistance in the preparation of the containers for the samples, Carlo Ionta for technical assistance in data-analysis, Luigi Verolino (University of Naples Federico II) and Gaetano Campi (CNR-IC), for preliminary discussions. should read: The authors wish to thank Luigi Nicolais (CNR), Glenn Most (SNS, Pisa), Daniel Koger (Lindsey Wilson College,Kentucky, US), G. Neville Greaves (University of Cambridge, UK) for valuable discussions and revisions of the present study, the ESRF Directorate for having granted the beamtime, the Biblioteca Nazionale 'Vittorio Emanuele III' of Naples, for lending us the samples (in particular, the officers Sofia Maresca and Vincenzo Boni), Eugenio Amendola (CNR-IPCB), for valuable assistance in the preparation of the containers for the samples, Carlo Ionta for technical assistance in data-analysis, Luigi Verolino (University of Naples Federico II) and Gaetano Campi (CNR-IC), for preliminary discussions. The European project VOXEL "Volumetric Medical X-Ray Imaging at extremely low dose" (HORIZON 2020-Fet Open; Project reference: 665207) is acknowledged for financial support. The COST action MP1203 "Advanced X-ray spatial and temporal metrology" is also acknowledged for supporting scientific missions.

Published
2016

18. Correction: Corrigendum: Virtual unrolling and deciphering of Herculaneum papyri by X-ray phase-contrast tomography

Author

Bukreeva, I., primary, Mittone, A., additional, Bravin, A., additional, Festa, G., additional, Alessandrelli, M., additional, Coan, P., additional, Formoso, V., additional, Agostino, R. G., additional, Giocondo, M., additional, Ciuchi, F., additional, Fratini, M., additional, Massimi, L., additional, Lamarra, A., additional, Andreani, C., additional, Bartolino, R., additional, Gigli, G., additional, Ranocchia, G., additional, and Cedola, A., additional

Published
2016
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19. Virtual unrolling and deciphering of Herculaneum papyri by X-ray phase-contrast tomography

Author

Bukreeva, I., primary, Mittone, A., additional, Bravin, A., additional, Festa, G., additional, Alessandrelli, M., additional, Coan, P., additional, Formoso, V., additional, Agostino, R. G., additional, Giocondo, M., additional, Ciuchi, F., additional, Fratini, M., additional, Massimi, L., additional, Lamarra, A., additional, Andreani, C., additional, Bartolino, R., additional, Gigli, G., additional, Ranocchia, G., additional, and Cedola, A., additional

Published
2016
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29. Metallomesogens as biaxial dopants in a calamitic nematic liquid crystal

Author

Ayeb H., Ciuchi F., Lombardo G., and Barberi R.

Subjects
ORDER, ELECTRIC-FIELD
Abstract

The electric field induced nematic order reconstruction is a way to achieve controlled transitions between uniaxial nematic textures with different topologies, hence allowing intrinsic textural bistability. The order reconstruction connects perpendicular nematic director orientations by exchanging two eigenvalues of the nematic order tensor Q, implying intermediate transient biaxial order. This phenomenon avoids the full nematic melting; in fact the nematic scalar order parameter does not vanish. The Biaxial Order Reconstruction in a calamitic Nematic (BORN) is mainly governed by the biaxial coherence length xi(b). Therefore, by varying xi(b), one can favour or inhibit the transient biaxial order. Recently, it has been demonstrated that xi(b) can be controlled by suitable dopants and in this work we study the BORN transition threshold for liquid crystal mixtures made of the commercial nematic liquid crystal E7 and three different metallomesogens with board-like shape.

Published
2008

30. Electrically controlled defects at a liquid crystal-polyimide interface

Author

Ciuchi, F, Giocondo, M, and Barberi, R

Subjects
DISPERSION, LATEX-PARTICLES, NEMATIC SOLUTION
Abstract

We report results on the effect of introducing a small quantity of oligomer particles inside a liquid crystal (LC) display. We observe a dramatic change in the properties of the LC-substrate interface. Upon applying an electric field, a pi-wall defect network appears that is stable in the absence of further electric perturbation but can be erased by a suitable pulse in a well-defined range of temperature and frequency. The appearance of the defects and their dimensions depend on the cell age, i.e. on the time required by the guest to deposit on the surface. Hypotheses on the phenomenon are reported.

Published
2008

31. Control of transient biaxial order in calamitic nematics

Author

Ciuchi F, Ayeb H, Lombardo G, Barberi R, and Durand GE

Subjects
MOLECULES, STATES, PHASE, FIELD, LIQUID-CRYSTALS
Abstract

The biaxial order reconstruction in nematics (BORN) is a dynamical effect which can change the topology of nematic textures. The BORN can be induced in a nematic material submitted to strong external constraints, as in the case of bulk textural distortions due to an electric field in a pi cell. In this work, we show how suitable dopants for a thermotropic calamitic nematic can influence its transient biaxial order and, hence, the electric BORN threshold. (c) 2007 American Institute of Physics.

Published
2007

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