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Tavagnacco L, Chiessi E, Severini L, Franco S, Buratti E, Capocefalo A, Brasili F, Mosca Conte A, Missori M, Angelini R, Sennato S, Mazzuca C, Zaccarelli E. Molecular origin of the two-step mechanism of gellan aggregation. Sci Adv 2023; 9:eadg4392. [PMID: 36897940 PMCID: PMC10005172 DOI: 10.1126/sciadv.adg4392] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 02/02/2023] [Indexed: 05/31/2023]
Abstract
Among hydrocolloids, gellan is one of the most studied polysaccharides due to its ability to form mechanically stable gels. Despite its long-standing use, the gellan aggregation mechanism is still not understood because of the lack of atomistic information. Here, we fill this gap by developing a new gellan force field. Our simulations offer the first microscopic overview of gellan aggregation, detecting the coil to single-helix transition at dilute conditions and the formation of higher-order aggregates at high concentration through a two-step process: first, the formation of double helices and then their assembly into superstructures. For both steps, we also assess the role of monovalent and divalent cations, complementing simulations with rheology and atomic force microscopy experiments and highlighting the leading role of divalent cations. These results pave the way for future use of gellan-based systems in a variety of applications, from food science to art restoration.
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Affiliation(s)
- Letizia Tavagnacco
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
| | - Ester Chiessi
- Department of Chemical Science and Technologies, University of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133 Rome, Italy
| | - Leonardo Severini
- Department of Chemical Science and Technologies, University of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133 Rome, Italy
| | - Silvia Franco
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
| | - Elena Buratti
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via L. Borsari 46, 44121 Ferrara, Italy
| | - Angela Capocefalo
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
| | - Francesco Brasili
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
| | - Adriano Mosca Conte
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
| | - Mauro Missori
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
| | - Roberta Angelini
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
| | - Simona Sennato
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
| | - Claudia Mazzuca
- Department of Chemical Science and Technologies, University of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133 Rome, Italy
| | - Emanuela Zaccarelli
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy
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Scatigno C, Prieto-Taboada N, Preite Martinez M, Conte AM, Madariaga JM. A non-invasive spectroscopic study to evaluate both technological features and conservation state of two types of ancient Roman coloured bricks. Spectrochim Acta A Mol Biomol Spectrosc 2018; 204:55-63. [PMID: 29902771 DOI: 10.1016/j.saa.2018.06.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 05/28/2018] [Accepted: 06/07/2018] [Indexed: 06/08/2023]
Abstract
The study of both original and decaying compounds is relevant in understanding the chemistry behind the deterioration processes, above all in open museum contexts where environmental stressors affect the artefacts. In this sense, a combination of non-invasive spectroscopy techniques (Raman spectroscopy, μ-X-ray fluorescence and X-ray diffraction) was applied on an ancient Roman building (130 CE), the "Casa di Diana" Mithraeum at Ostia Antica archaeological site. The aim is to study the raw materials, manufacturing and decaying products of the two observed types of Roman fired bricks (red and yellow) that compose the building. The present study estimates an illite raw material of carbonate-bearing marine clay likely referring to the common deposits of central/southern Italy, which contain calcite as accessory phase and a-plastic fraction constituted by quartz, feldspar and opaques. This clay material was added with volcanic temper characterised by abundant clinopyroxene and analcime (from analcimization of leucite) that are typical of the Roman Province volcanism. The firing would be probably the result of oxidizing conditions, as proved by the hematite presence. Thanks to the existence of specific neoformed mineral phases during firing it was possible to assess different temperatures ranges. In detail, the red/orange bricks, for the existence of gehlenite (formed from calcite and its reaction with silicates), were fired at 800-900 °C range; whereas, the yellow ones are characterised by the lack of gehlenite and the disappearance of illite/muscovite, which indicates firing temperature at over 900 °C. Regarding the decaying products, the gypsum covers most of the surface of most bricks, both red and the yellow ones, but these latter are more susceptible to environmental stressors (sulphates and carbonates). Therefore, this work points out how by integrated non-invasive approaches it is possible trace back to original firing temperature, technology of manufacture, interpreting ceramic data.
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Affiliation(s)
- C Scatigno
- NAST Centre, University of Rome "Tor Vergata", Via delle Ricerca Scientifica 1, 00133 Rome, Italy; Department of Chemical Science and Technologies, University of Rome "Tor Vergata", Via delle Ricerca Scientifica 1, 00133 Rome, Italy.
| | - N Prieto-Taboada
- Department of Analytical Chemistry, University the Basque Country, (UPV/EHU), Barrio Sarriena s/n, 48940 Leioa, Spain
| | - M Preite Martinez
- Department of Earth Science, University of Rome "La Sapienza", Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - A M Conte
- National Research Council (CNR) - Institute of Geosciences of Earth Resources (IGG), Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - J M Madariaga
- Department of Analytical Chemistry, University the Basque Country, (UPV/EHU), Barrio Sarriena s/n, 48940 Leioa, Spain
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Lorenzoni A, Mosca Conte A, Pecchia A, Mercuri F. Nanoscale morphology and electronic coupling at the interface between indium tin oxide and organic molecular materials. Nanoscale 2018; 10:9376-9385. [PMID: 29738001 DOI: 10.1039/c8nr02341g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The correlation between nanoscale morphology and charge injection rates at the interface between an organic semiconductor layer and a transparent metal oxide electrode was investigated by integrating molecular dynamics simulations with electronic structure calculations. The simulation approach proposed has been applied to the analysis of the hole injection mechanism at the interface between an amorphous layer of tris[(3-phenyl-1H-benzimidazol-1-yl-2(3H)-ylidene)-1,2-phenylene]Ir (DPBIC), a hole transport and emitter molecule, and the surface of indium tin oxide (ITO), a material commonly used as anode in OLEDs. The link between interface morphology and charge injection was investigated by implementing a two-step, top-down simulation approach. Namely, nanoscale molecular aggregation phenomena at the organic/electrode interface were first assessed by molecular dynamics simulations, mimicking different processing conditions, and followed by density functional theory calculations of the electronic coupling between molecular levels and the manifold of electrode states involved in the charge injection process. The correlation between structural parameters and electronic coupling suggests a significant role of specific molecule/electrode configurations on charge transport processes at the interface, resulting in a broad distribution of charge injection rates, and highlights the link between molecular structure, nanoscale aggregation and processing in the realization of heterointerfaces for efficient charge injection in organic electronic devices.
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Affiliation(s)
- Andrea Lorenzoni
- Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), Consiglio Nazionale delle Ricerche (CNR), Via P. Gobetti 101, 40129 Bologna, Italy.
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Mosca Conte A, Pulci O, Bechstedt F. Electronic and optical properties of topological semimetal Cd 3As 2. Sci Rep 2017; 7:45500. [PMID: 28383018 PMCID: PMC5382546 DOI: 10.1038/srep45500] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 02/27/2017] [Indexed: 11/09/2022] Open
Abstract
Using ab initio density functional theory the band structure and the dielectric function of a bct Cd3As2 crystal are calculated. We find a Dirac semimetal with two Dirac nodes k± near the Γ point on the tetragonal axis. The bands near the Fermi level exhibit a linear behavior. The resulting Dirac cones are anisotropic and the electron-hole symmetry is destroyed along the tetragonal axis. Along this axis the symmetry-protected band linearity only exists in a small energy interval. The Dirac cones seemingly found by ARPES in a wider energy range are interpreted in terms of pseudo-linear bands. The behavior as 3D graphene-like material is traced back to As p orbital pointing to Cd vacancies, in directions which vary throughout the unit cell. Because of the Dirac nodes the dielectric functions (imaginary part) show a plateau for vanishing frequencies whose finite value is proportional to the Sommerfeld fine structure constant but varies with the light polarization. The consequences of the anisotropy of the Dirac cones are highlighted for the polarization dependence of the infrared optical conductivity.
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Affiliation(s)
- Adriano Mosca Conte
- ISMN, Consiglio Nazionale delle Ricerche, Via Salaria Km 29,300 00015 Monterotondo Stazione (Roma) - Italy.,Dipartimento di Fisica, Università di Roma 'Tor Vergata', Via della Ricerca Scientifica 1, I-00133, Rome, Italy
| | - Olivia Pulci
- Dipartimento di Fisica, Università di Roma 'Tor Vergata', Via della Ricerca Scientifica 1, I-00133, Rome, Italy.,I.N.F.N, - Sezione di Roma 'Tor Vergata', and CNR-ISM, Roma, Italy
| | - Friedhelm Bechstedt
- IFTO, Friedrich-Schiller-Universität and ETSF, Max-Wien-Platz 1, 07743 Jena, Germany
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Varsano D, Coccia E, Pulci O, Conte AM, Guidoni L. Ground state structures and electronic excitations of biological chromophores at Quantum Monte Carlo/Many Body Green’s Function Theory level. COMPUT THEOR CHEM 2014. [DOI: 10.1016/j.comptc.2014.03.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Conte AM, Guidoni L, Del Sole R, Pulci O. Many-body study of the photoisomerization of the minimal model of the retinal protonated Schiff base. Chem Phys Lett 2011. [DOI: 10.1016/j.cplett.2011.09.041] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Conte AM, Ippoliti E, Del Sole R, Carloni P, Pulci O. Many-Body Perturbation Theory Extended to the Quantum Mechanics/Molecular Mechanics Approach: Application to Indole in Water Solution. J Chem Theory Comput 2009; 5:1822-8. [DOI: 10.1021/ct800528e] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Adriano Mosca Conte
- NAST, ETSF, CNR INFM-SMC, Department of Physics, Universita’ di Roma Tor Vergata, Via della Ricerca Scientifica 1, Roma, Italy, Democritos, SISSA—Scuola Internazionale Superiore di Studi Avanzati, via Beirut 2-4, I-34014 Trieste, Italy, and Italian Institute of Technology, SISSA Unit, Via Beirut 2−4, Trieste, Italy
| | - Emiliano Ippoliti
- NAST, ETSF, CNR INFM-SMC, Department of Physics, Universita’ di Roma Tor Vergata, Via della Ricerca Scientifica 1, Roma, Italy, Democritos, SISSA—Scuola Internazionale Superiore di Studi Avanzati, via Beirut 2-4, I-34014 Trieste, Italy, and Italian Institute of Technology, SISSA Unit, Via Beirut 2−4, Trieste, Italy
| | - Rodolfo Del Sole
- NAST, ETSF, CNR INFM-SMC, Department of Physics, Universita’ di Roma Tor Vergata, Via della Ricerca Scientifica 1, Roma, Italy, Democritos, SISSA—Scuola Internazionale Superiore di Studi Avanzati, via Beirut 2-4, I-34014 Trieste, Italy, and Italian Institute of Technology, SISSA Unit, Via Beirut 2−4, Trieste, Italy
| | - Paolo Carloni
- NAST, ETSF, CNR INFM-SMC, Department of Physics, Universita’ di Roma Tor Vergata, Via della Ricerca Scientifica 1, Roma, Italy, Democritos, SISSA—Scuola Internazionale Superiore di Studi Avanzati, via Beirut 2-4, I-34014 Trieste, Italy, and Italian Institute of Technology, SISSA Unit, Via Beirut 2−4, Trieste, Italy
| | - Olivia Pulci
- NAST, ETSF, CNR INFM-SMC, Department of Physics, Universita’ di Roma Tor Vergata, Via della Ricerca Scientifica 1, Roma, Italy, Democritos, SISSA—Scuola Internazionale Superiore di Studi Avanzati, via Beirut 2-4, I-34014 Trieste, Italy, and Italian Institute of Technology, SISSA Unit, Via Beirut 2−4, Trieste, Italy
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Vitali L, Fabris S, Conte AM, Brink S, Ruben M, Baroni S, Kern K. Electronic structure of surface-supported bis(phthalocyaninato) terbium(III) single molecular magnets. Nano Lett 2008; 8:3364-8. [PMID: 18800852 DOI: 10.1021/nl801869b] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The electronic structure of isolated bis(phthalocyaninato) terbium(III) molecules, a novel single-molecular-magnet (SMM), supported on the Cu(111) surface has been characterized by density functional theory and scanning tunneling spectroscopy. These studies reveal that the interaction with the metal surface preserves both the molecular structure and the large spin magnetic moment of the metal center. The 4f electron states are not perturbed by the adsorption while a strong molecular/metal interaction can induce the suppression of the minor spin contribution delocalized over the molecular ligands. The calculations show that the inherent spin magnetic moment of the molecule is only weakly affected by the interaction with the surface and suggest that the SMM character might be preserved.
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Affiliation(s)
- Lucia Vitali
- Max-Planck-Institut fur Festkorperforschung, D-70569 Stuttgart, Germany.
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Simone F, Pappalardo G, Maiani G, Guadalaxara A, Bugianesi R, Conte AM, Azzini E, Mobarhan S. Accumulation and interactions of beta-carotene and alpha-tocopherol in patients with adenomatous polyps. Eur J Clin Nutr 2002; 56:546-50. [PMID: 12032655 DOI: 10.1038/sj.ejcn.1601354] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2001] [Revised: 09/27/2001] [Accepted: 09/27/2001] [Indexed: 11/09/2022]
Abstract
OBJECTIVE The aims of the present study were: (1) to determine whether short-term supplementation of beta-carotene (BC) or vitamin E (VE; alpha-tocopherol) would result in their respective accumulation in normal colonic mucosa and in adenomatous polyps; (2) to determine whether the intake of BC would interfere with the concentration of VE in these target tissues. DESIGN Blood and colonic biopsy samples were taken before and after supplementation. SUBJECTS Eighteen volunteers with colonic adenomatous polyps were enrolled into this study. INTERVENTIONS The supplementation lasted for 43 days and patients were examined over the whole period. Subjects were randomised into four groups according to the four different supplementations: placebo, natural BC (25 000 IU/day), natural VE (400 IU/day), combination BC/VE. RESULTS Initially we were aiming for recruitment of 20 patients in each group, however after 2 y of study (1997-1999), we terminated the study because of slow recruitment and analysed the data. In placebo subjects after supplementation, the plasma concentrations of BC and VE remained unchanged, however only two patients were recruited in this group and therefore we did not include this group in our final analysis. In BC group, the plasma BC concentrations increased significantly (P<0.001), while VE concentrations were unchanged. In VE group, VE concentrations increased (P<0.01) and BC did not change, and in BC/VE group both BC (P<0.001) and VE levels (P<0.01) increased significantly. After supplementation, the tissue concentration of BC in normal colonic mucosa in BC group increased significantly (P<0.01) while the VE concentration did not change. In VE group, the concentration of VE in normal colonic mucosa increased slightly but did not reach statistical significance. However, VE concentration increased significantly (P<0.05) in the polyps of this group. In BC/VE group, in which patients received the combination treatment, the BC concentration of normal colonic mucosa increased (P<0.05) but, surprisingly, the VE concentration decreased significantly (P<0.01). Interestingly in the polyps, although the BC concentration increased (P<0.01), the concentration of VE was reduced moderately but did not reach statistical significance. CONCLUSIONS Supplementation of BC in doses used in this study may have significantly interfered with the VE concentration in the examined tissue and probably with its metabolic pathway.
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Affiliation(s)
- F Simone
- Human Nutrition Unit, National Research Institute for Food and Nutrition, Rome, Italy
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Pappalardo G, Conte AM, Casciani E, Gualdi GF. [Conventional colonoscopy and colonography with magnetic resonance in the diagnosis of endoluminal lesions of the colon]. Recenti Prog Med 2001; 92:385-7. [PMID: 11433715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
The diagnostic ability of Magnetic Resonance Colonography (MRC) in detecting colonic endoluminal masses was compared with that of conventional colonoscopy (CC) and related to the findings from histologic examination. In seventy consecutive patients MRC achieved a diagnostic accuracy similar to CC. Therefore MRC could be useful in screening patients at high risk for colonic cancer. However every patient with MRC-detected endoluminal lesion must undergo CC for histologic diagnosis.
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Affiliation(s)
- G Pappalardo
- Dipartimento di Chirurgia Generale, Specialità Chirurgiche e Trapianti d'Organo Paride Stefanini, Università La Sapienza, Roma
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