1
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Kaciulis S, Bolli E, Varone A, Richetta M, Narducci R, Di Vona M, Ciotta E, Pizzoferrato R. Adsorption of heavy metals by layered double hydroxides grown in situ on Al foam. SURF INTERFACE ANAL 2020. [DOI: 10.1002/sia.6856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- S. Kaciulis
- Institute for the Study of Nanostructured Materials, ISMN‐CNR Rome Italy
| | - E. Bolli
- Institute for the Study of Nanostructured Materials, ISMN‐CNR Rome Italy
- Department of Industrial Engineering University of Rome Tor Vergata Rome Italy
| | - A. Varone
- Department of Industrial Engineering University of Rome Tor Vergata Rome Italy
| | - M. Richetta
- Department of Industrial Engineering University of Rome Tor Vergata Rome Italy
| | - R. Narducci
- Department of Industrial Engineering University of Rome Tor Vergata Rome Italy
| | - M.L. Di Vona
- Department of Industrial Engineering University of Rome Tor Vergata Rome Italy
| | - E. Ciotta
- Department of Industrial Engineering University of Rome Tor Vergata Rome Italy
| | - R. Pizzoferrato
- Department of Industrial Engineering University of Rome Tor Vergata Rome Italy
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2
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Liccardi G, Calzetta L, Berra A, Caiazzo R, Califano F, Ciccarelli A, Cutajar M, D'Amato M, De Bartolomeis F, Dello Iacono I, Gargano D, Lo Schiavo M, Madonna F, Maniscalco M, Milanese M, Montera C, Narducci R, Papa G, Pedicini A, Sabatino G, Sacerdoti C, Savoia A, Stanziola A, Bilò MB, Rogliani P. Unmet needs and relationship between general practitioners (GPs) and allergists living in Campania region (southern Italy). Eur Ann Allergy Clin Immunol 2020; 52:230-234. [PMID: 32374559 DOI: 10.23822/eurannaci.1764-1489.127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- G Liccardi
- Department of Pulmonology, Haematology and Oncology. Division of Pulmonology. Unit of Allergology, High Speciality A.Cardarelli Hospital, Naples, Italy.,Postgraduate School of Respiratory Medicine, Department of Experimental Medicine, University of Rome Tor Vergata, Rome, Italy
| | - L Calzetta
- Postgraduate School of Respiratory Medicine, Department of Experimental Medicine, University of Rome Tor Vergata, Rome, Italy.,Department of Experimental Medicine, Unit of Respiratory Medicine University of Rome, Tor Vergata, Rome, Italy
| | - A Berra
- Respiratory Allergy Unit. G. Da Procida Hospital, Salerno, Italy
| | - R Caiazzo
- Allergy Unit, ASL (Sanitary District n°12), Caserta, Italy
| | - F Califano
- Allergy and Clinical Immunology, G. Fucito, Hospital and University Hospital, Salerno, Italy
| | - A Ciccarelli
- Allergy Unit, Presidio Sanitario Polispecialistico Loreto Crispi Naples, Italy
| | - M Cutajar
- Allergy Center, Division of Internal Medicine. Ospedali Riuniti Penisola Sorrentina, Sorrento, Naples, Italy
| | - M D'Amato
- Department of Respiratory Disease, Federico II University AO Dei Colli, Naples, Italy
| | - F De Bartolomeis
- Allergy Unit. High Speciality San Giuseppe Moscati Hospital, Avellino, Italy
| | - I Dello Iacono
- Unit of Allergology. Division of Internal Medicine, Fatebenefratelli Hospital, Benevento, Italy
| | - D Gargano
- Allergy Unit. High Speciality San Giuseppe Moscati Hospital, Avellino, Italy
| | - M Lo Schiavo
- Allergy and Clinical Immunology, G. Fucito, Hospital and University Hospital, Salerno, Italy
| | - F Madonna
- Allergy Unit. ASL (Sanitary District n°12), Caserta, Italy
| | - M Maniscalco
- Pulmonary Rehabilitation Unit ICS Maugeri Telese Terme, Benevento, Italy
| | - M Milanese
- Division of Pulmonology, S.Corona Hospital, Pietra Ligure, Savona, Italy
| | - C Montera
- Allergy and Clinical Immunology, G. Fucito, Hospital and University Hospital, Salerno, Italy
| | - R Narducci
- Unit of Allergology, San Michele Clinic, Maddaloni, Caserta, Italy
| | - G Papa
- ASL (Sanitary District), Avellino, Italy
| | - A Pedicini
- Unit of Allergology. Division of Internal Medicine, Fatebenefratelli Hospital, Benevento, Italy
| | | | | | - A Savoia
- Unit of Allergology. Division of Internal Medicine, Fatebenefratelli Hospital, Benevento, Italy
| | - A Stanziola
- Department of Respiratory Disease, Federico II University AO Dei Colli, Naples, Italy
| | - M B Bilò
- Allergy Unit, Department of Internal Medicine, University Hospital Ospedali Riuniti, Ancona, Department of Clinical and Molecular Sciences, Polytechnic University of Marche, Italy
| | - P Rogliani
- Postgraduate School of Respiratory Medicine, Department of Experimental Medicine, University of Rome Tor Vergata, Rome, Italy.,Department of Experimental Medicine, Unit of Respiratory Medicine University of Rome, Tor Vergata, Rome, Italy
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3
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Becerra-Arciniegas RA, Narducci R, Ercolani G, Antonaroli S, Sgreccia E, Pasquini L, Knauth P, Di Vona M. Alkaline stability of model anion exchange membranes based on poly(phenylene oxide) (PPO) with grafted quaternary ammonium groups: Influence of the functionalization route. POLYMER 2019. [DOI: 10.1016/j.polymer.2019.121931] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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4
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Masi A, Narducci R, Mannaioni G. Harnessing ionic mechanisms to achieve disease modification in neurodegenerative disorders. Pharmacol Res 2019; 147:104343. [PMID: 31279830 DOI: 10.1016/j.phrs.2019.104343] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 06/19/2019] [Accepted: 07/03/2019] [Indexed: 12/12/2022]
Abstract
Progressive neuronal death is the key pathogenic event leading to clinical symptoms in neurodegenerative disorders (NDDs). Neuroprotective treatments are virtually unavailable, partly because of the marked internal heterogeneity of the mechanisms underlying pathology. Targeted neuroprotection would require deep mechanistic knowledge across the entire aetiological spectrum of each NDD and the development of tailored treatments. Although ideal, this strategy appears challenging, as it would require a degree of characterization of both the disease and the patient that is currently unavailable. The alternate strategy is to search for commonalities across molecularly distinct NDD forms and exploit these for the development of drugs with broad-spectrum efficacy. In this view, mounting evidence points to ionic mechanisms (IMs) as targets with potential therapeutic efficacy across distinct NDD subtypes. The scope of this review is to present clinical and preclinical evidence supporting the link between disruption of IMs and neuronal death in specific NDDs and to critically revise past and ongoing attempts of harnessing IMs for the development of neuroprotective treatments.
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Affiliation(s)
- A Masi
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, Florence, Italy; School of Pharmacy, University of Camerino, Camerino, Italy.
| | - R Narducci
- Italian Institute of Technology (IIT), Department of Neuroscience and Brain Technologies, Genova, Italy
| | - G Mannaioni
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, Florence, Italy; Toxicology Unit, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy
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5
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Onesto V, Villani M, Narducci R, Malara N, Imbrogno A, Allione M, Costa N, Coppedè N, Zappettini A, Cannistraci CV, Cancedda L, Amato F, Di Fabrizio E, Gentile F. Cortical-like mini-columns of neuronal cells on zinc oxide nanowire surfaces. Sci Rep 2019; 9:4021. [PMID: 30858456 PMCID: PMC6411964 DOI: 10.1038/s41598-019-40548-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [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: 10/26/2018] [Accepted: 02/18/2019] [Indexed: 11/25/2022] Open
Abstract
A long-standing goal of neuroscience is a theory that explains the formation of the minicolumns in the cerebral cortex. Minicolumns are the elementary computational units of the mature neocortex. Here, we use zinc oxide nanowires with controlled topography as substrates for neural-cell growth. We observe that neuronal cells form networks where the networks characteristics exhibit a high sensitivity to the topography of the nanowires. For certain values of nanowires density and fractal dimension, neuronal networks express small world attributes, with enhanced information flows. We observe that neurons in these networks congregate in superclusters of approximately 200 neurons. We demonstrate that this number is not coincidental: the maximum number of cells in a supercluster is limited by the competition between the binding energy between cells, adhesion to the substrate, and the kinetic energy of the system. Since cortical minicolumns have similar size, similar anatomical and topological characteristics of neuronal superclusters on nanowires surfaces, we conjecture that the formation of cortical minicolumns is likewise guided by the interplay between energy minimization, information optimization and topology. For the first time, we provide a clear account of the mechanisms of formation of the minicolumns in the brain.
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Affiliation(s)
- V Onesto
- Center for Advanced Biomaterials for HealthCare, Istituto Italiano di Tecnologia, 80125, Naples, Italy.,Department of Experimental and Clinical Medicine, University of Magna Graecia, 88100, Catanzaro, Italy
| | - M Villani
- IMEM-CNR Parco Area delle Scienze 37/A, 43124, Parma, Italy
| | - R Narducci
- Istituto Italiano di Tecnologia, Via Morego 30, 16163, Genova, Italy
| | - N Malara
- Department of Experimental and Clinical Medicine, University of Magna Graecia, 88100, Catanzaro, Italy
| | - A Imbrogno
- Tyndall National Institute, Cork, T12 R5CP, Ireland
| | - M Allione
- PSE division, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - N Costa
- Health Department, University of Magna Graecia, 88100, Catanzaro, Italy
| | - N Coppedè
- IMEM-CNR Parco Area delle Scienze 37/A, 43124, Parma, Italy
| | - A Zappettini
- IMEM-CNR Parco Area delle Scienze 37/A, 43124, Parma, Italy
| | - C V Cannistraci
- Biomedical Cybernetics Group, Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering (CMCB), Center for Systems Biology Dresden (CSBD), Department of Physics, Technische Universität Dresden, Tatzberg 47/49, 01307, Dresden, Germany.,Brain Bio-Inspired Computing (BBC) Lab, IRCCS Centro Neurolesi "Bonino Pulejo", Messina, 98124, Italy
| | - L Cancedda
- Istituto Italiano di Tecnologia, Via Morego 30, 16163, Genova, Italy.,Dulbecco Telethon Institute, Rome, Italy
| | - F Amato
- Department of Electrical Engineering and Information Technology, University Federico II, Naples, Italy
| | - Enzo Di Fabrizio
- PSE division, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - F Gentile
- Department of Electrical Engineering and Information Technology, University Federico II, Naples, Italy.
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6
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Bruno RM, Stea F, Sicari R, Ghiadoni L, Taddei S, Ungar A, Bonuccelli U, Tognoni G, Cintoli S, Del Turco S, Sbrana S, Gargani L, D’Angelo G, Pratali L, Berardi N, Maffei L, Picano E, Andreassi M, Angelucci A, Baldacci F, Baroncelli L, Begenisic T, Bellinvia P, Biagi L, Bonaccorsi J, Bonanni E, Borghini A, Braschi C, Broccardi M, Caleo M, Carlesi C, Carnicelli L, Cartoni G, Cecchetti L, Cenni M, Ceravolo R, Chico L, Cioni G, Costa M, D’Ascanio P, De Nes M, Di Coscio E, Di Galante M, di Lascio N, Faita F, Falorni I, Faraguna U, Fenu A, Fortunato L, Franco R, Gargiulo R, Giorgi F, Iannarella R, Iofrida C, Kusmic C, Limongi F, Maestri M, Maffei M, Maggi S, Mainardi M, Mammana L, Marabotti A, Mariotti V, Melissari E, Mercuri A, Molinaro S, Narducci R, Navarra T, Noale M, Pagni C, Palumbo S, Pasquariello R, Pellegrini S, Pietrini P, Pizzorusso T, Poli A, Retico A, Ricciardi E, Rota G, Sale A, Scabia G, Scali M, Scelfo D, Siciliano G, Tonacci A, Tosetti M, Turchi S, Volpi L. Vascular Function Is Improved After an Environmental Enrichment Program. Hypertension 2018; 71:1218-1225. [DOI: 10.1161/hypertensionaha.117.10066] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 08/09/2017] [Accepted: 03/15/2018] [Indexed: 11/16/2022]
Abstract
Environmental enrichment may slow cognitive decay possibly acting through an improvement in vascular function. Aim of the study was to assess the effects of a 7-month cognitive, social, and physical training program on cognitive and vascular function in patients with mild cognitive impairment. In a single-center, randomized, parallel-group study, 113 patients (age, 65–89 years) were randomized to multidomain training (n=55) or usual care (n=58). All participants underwent neuropsychological tests and vascular evaluation, including brachial artery flow-mediated dilation, carotid–femoral pulse wave velocity, carotid distensibility, and assessment of circulating hematopoietic CD34+ and endothelial progenitor cells. At study entry, an age-matched control group (n=45) was also studied. Compared with controls, patients had at study entry a reduced flow-mediated dilation (2.97±2.14% versus 3.73±2.06%;
P
=0.03) and hyperemic stimulus (shear rate area under the curve, 19.1±15.7 versus 25.7±15.1×10
−3
;
P
=0.009); only the latter remained significant after adjustment for confounders (
P
=0.03). Training improved Alzheimer disease assessment scale cognitive (training, 14.0±4.8 to 13.1±5.5; nontraining, 12.1±3.9 to 13.2±4.8;
P
for interaction visit×training=0.02), flow-mediated dilation (2.82±2.19% to 3.40±1.81%, 3.05±2.08% to 2.24±1.59%;
P
=0.006;
P
=0.023 after adjustment for diameter and shear rate area under the curve), and circulating hematopoietic CD34
+
cells and prevented the decline in carotid distensibility (18.4±5.3 to 20.0±6.6, 23.9±11.0 to 19.5±7.1 Pa
−1
;
P
=0.005). The only clinical predictor of improvement of cognitive function after training was established hypertension. There was no correlation between changes in measures of cognitive and vascular function. In conclusion, a multidomain training program slows cognitive decline, especially in hypertensive individuals. This effect is accompanied by improved systemic endothelial function, mobilization of progenitor CD34
+
cells, and preserved carotid distensibility.
Clinical Trial Registration—
URL:
http://www.clinicaltrials.gov
. Unique identifier: NCT01725178.
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Affiliation(s)
- Rosa Maria Bruno
- From the Department of Clinical and Experimental Medicine, University of Pisa, Italy (R.M.B., F.S., L.G., S.T., U.B.)
- Institute of Clinical Physiology of the National Research Council (CNR), Pisa, Italy (R.M.B., F.S., R.S., S.D.T., S.S., L.G., G.D., L.P., E.P.)
| | - Francesco Stea
- From the Department of Clinical and Experimental Medicine, University of Pisa, Italy (R.M.B., F.S., L.G., S.T., U.B.)
- Institute of Clinical Physiology of the National Research Council (CNR), Pisa, Italy (R.M.B., F.S., R.S., S.D.T., S.S., L.G., G.D., L.P., E.P.)
| | - Rosa Sicari
- Institute of Clinical Physiology of the National Research Council (CNR), Pisa, Italy (R.M.B., F.S., R.S., S.D.T., S.S., L.G., G.D., L.P., E.P.)
| | - Lorenzo Ghiadoni
- From the Department of Clinical and Experimental Medicine, University of Pisa, Italy (R.M.B., F.S., L.G., S.T., U.B.)
| | - Stefano Taddei
- From the Department of Clinical and Experimental Medicine, University of Pisa, Italy (R.M.B., F.S., L.G., S.T., U.B.)
| | | | - Ubaldo Bonuccelli
- From the Department of Clinical and Experimental Medicine, University of Pisa, Italy (R.M.B., F.S., L.G., S.T., U.B.)
| | - Gloria Tognoni
- Azienda Ospedaliero Universitaria Careggi, University of Florence, Italy (A.U.); Azienda Ospedaliero Universitaria Pisana, Italy (G.T., S.C.)
| | - Simona Cintoli
- Azienda Ospedaliero Universitaria Careggi, University of Florence, Italy (A.U.); Azienda Ospedaliero Universitaria Pisana, Italy (G.T., S.C.)
| | - Serena Del Turco
- Institute of Clinical Physiology of the National Research Council (CNR), Pisa, Italy (R.M.B., F.S., R.S., S.D.T., S.S., L.G., G.D., L.P., E.P.)
| | - Silverio Sbrana
- Institute of Clinical Physiology of the National Research Council (CNR), Pisa, Italy (R.M.B., F.S., R.S., S.D.T., S.S., L.G., G.D., L.P., E.P.)
| | - Luna Gargani
- Institute of Clinical Physiology of the National Research Council (CNR), Pisa, Italy (R.M.B., F.S., R.S., S.D.T., S.S., L.G., G.D., L.P., E.P.)
| | - Gennaro D’Angelo
- Institute of Clinical Physiology of the National Research Council (CNR), Pisa, Italy (R.M.B., F.S., R.S., S.D.T., S.S., L.G., G.D., L.P., E.P.)
| | - Lorenza Pratali
- Institute of Clinical Physiology of the National Research Council (CNR), Pisa, Italy (R.M.B., F.S., R.S., S.D.T., S.S., L.G., G.D., L.P., E.P.)
| | | | | | - Eugenio Picano
- Institute of Clinical Physiology of the National Research Council (CNR), Pisa, Italy (R.M.B., F.S., R.S., S.D.T., S.S., L.G., G.D., L.P., E.P.)
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Abstract
We present a mathematical model that quantifies the amount of information exchanged in bi-dimensional networks of nerve cells as a function of network connectivity Q. Upon varying Q over a significant range, we found that, from a certain cell density onwards, 90% of the maximal information transferred I(Q) in a random neuronal network is already reached with just 40% of the total possible connections Q among the cells. As a consequence, the system would not benefit from additional connections in terms of the amount of I(Q), in agreement with the tendency of brains to minimize Q because of its energetic costs. The model may reveal the circuits responsible for neurodegenerative disorders in that neurodegeneration can be regarded as a connective failure affecting information.
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Affiliation(s)
- V Onesto
- Department of Experimental and Clinical Medicine, University of Magna Graecia, 88100 Catanzaro, Italy
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8
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Masi A, Narducci R, Landucci E, Moroni F, Mannaioni G. MPP(+) -dependent inhibition of Ih reduces spontaneous activity and enhances EPSP summation in nigral dopamine neurons. Br J Pharmacol 2014; 169:130-42. [PMID: 23323755 DOI: 10.1111/bph.12104] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 12/21/2012] [Accepted: 01/07/2013] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE 1-Methyl-4-phenylpyridinium (MPP(+) ), a potent parkinsonizing agent in primates and rodents, is a blocker of mitochondrial complex I, therefore MPP(+) -induced parkinsonism is believed to depend largely on mitochondrial impairment. However, it has recently been proposed that other mechanisms may participate in MPP(+) -induced toxicity. We tackled this issue by probing the effects of an acute application of MPP(+) on substantia nigra pars compacta (SNc) dopamine (DA) neurons. EXPERIMENTAL APPROACH The effects of MPP(+) on SNc DA neurons in acute midbrain slices were investigated with electrophysiology techniques. KEY RESULTS MPP(+) (50 μM) was able to (i) hyperpolarize SNc DA neurons by ∼6 mV; (ii) cause an abrupt and marked (over 50%) reduction of the spontaneous activity; and (iii) inhibit the hyperpolarization-activated inward current (Ih ). MPP(+) shifted Ih activation curve towards negative potentials by ∼11 mV both in Wistar rats and in C57/BL6 mice. Inhibition was voltage- and concentration-dependent (Imax = 47%, IC50 = 7.74 μM). MPP(+) slowed Ih activation kinetics at all potentials. These effects were not dependent on (i) block of mitochondrial complex I/fall of ATP levels; (ii) activation of type 2 DA receptor; and (iii) alteration of cAMP metabolism. Finally, MPP(+) -dependent inhibition of Ih facilitated temporal summation of evoked EPSPs in SNc DA, but not in CA1 hippocampal neurons. CONCLUSION AND IMPLICATIONS Reduced functionality of Ih in SNc DA neurons, via increased responsiveness towards synaptic excitation, might play a role in MPP(+) -induced parkinsonism and, possibly, in the pathogenesis of human Parkinson's.
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Affiliation(s)
- A Masi
- Department of Neurosciences, Psychology, Drug Research and Child Health - Section of Pharmacology and Toxicology, University of Florence, Florence, Italy.
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9
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Narducci R, Di Vona M, Knauth P. Cation-conducting ionomers made by ion exchange of sulfonated poly-ether-ether-ketone: Hydration, mechanical and thermal properties and ionic conductivity. J Memb Sci 2014. [DOI: 10.1016/j.memsci.2014.03.073] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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10
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Paciaroni A, Casciola M, Cornicchi E, Marconi M, Onori G, Pica M, Narducci R. Temperature-Dependent Dynamics of Water Confined in Nafion Membranes. J Phys Chem B 2006; 110:13769-76. [PMID: 16836322 DOI: 10.1021/jp0572176] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We performed a neutron scattering study to investigate the dynamical behavior of water absorbed in Nafion at low hydration level as a function of temperature in the range 200-300 K. To single out the spectral contribution of the confined water, the measurements were done on samples hydrated with both H(2)O and D(2)O. Due to the strong incoherent scattering cross section of hydrogen atoms with respect to deuterium, in the difference spectra, the contribution from the Nafion membrane is subtracted out and the signal originates essentially from protons in the liquid phase. The main quantities we extracted as a function of the momentum transfer are the elastic incoherent structure factor (EISF) and the line width of the quasielastic component. Their trend suggests that the motion of hydrogen atoms can be schematized as a random jumping inside a confining region, which can be related to the boundaries of the space where water molecules move in the cluster they form around the sulfonic acid site. Through the calculated EISF, we obtained information on the size of such a region, which increases up to 260 K and then attains a constant value. Above this temperature, the number of water protons that are dynamically activated in the accessible time window increases with a faster rate. The jump diffusion dynamics is characterized by a typical jumping time which is stable at 5.3 ps up to approximately 260 K and then gradually decreases. The ensemble of the findings indicates that, within the limits of the energy resolution of the present experiment, water absorbed in the Nafion membrane undergoes a dynamical transition at around 260 K. We discuss the possible relationship of this dynamical onset with the behavior of the electrical conductivity of the membrane as a function of the temperature.
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Affiliation(s)
- A Paciaroni
- Dipartimento di Fisica dell'Università di Perugia and INFM-CRS SOFT Unità di Perugia, Via A. Pascoli, I-06123 Perugia, Italy.
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11
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12
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