1,355,118 research outputs found
Rilassometria NMR applicata allo studio della statua lignea di San Nicola di Mira (XVI secolo) al museo Diocesano di Palermo
No full textIn un recente studio condotto mediante Rilassometria NMR del nucleo 1H su legni moderni stagionati è stato mostrato che è possibile separare la curva di rilassamento della componente longitudinale della magnetizzazione nucleare dei nuclei 1H meno mobili (componente “solida”), attribuibili alle macromolecole, da quella dei nuclei a maggior mobilità (componente “liquida”), attribuibili all’acqua. Oltre a permettere di verificare la proporzionalità diretta tra ampiezza della componente liquida del segnale e massa d’acqua, l’analisi delle curve di rilassamento mediante distribuzioni quasi-continue del tempo di rilassamento longitudinale T1 permette di classificare le essenze lignee esaminate, mettendo in evidenza variazioni regolari di tale tempo nel passare da latifoglie a conifere. Alcune regolarità osservate possono essere giustificate assumendo un modello di scambio a due siti, con un tempo di scambio solido-liquido di qualche decina di ms. La stessa analisi, condotta su campioni di legno della statua di San Nicola di Mira (XVI secolo) recentemente restaurata e collocata presso il Museo Diocesano di Palermo, mostra che anche per il legno antico, sebbene fortemente degradato, valgono le stesse regolarità, ma con valori per i tempi di rilassamento e per il tempo di scambio solido-liquido che sono circa la metà di quelli osservati per il legno moderno. Si avanza l’ipotesi che questa accelerazione nei processi di rilassamento e di scambio sia associabile all’aumento del contributo paramagnetico, legato alla presenza di radicali liberi nel legno degradato, messo in evidenza in uno studio parallelo mediante EPR. Per il legno antico trattato non valgono le regolarità osservate per il legno non trattato, sia esso moderno od antico. Le regolarità riscontrate suggeriscono che la Rilassometria NMR possa essere utilizzata in futuro per analisi non distruttive volte alla classificazione delle essenze ed alla diagnosi del degrado di legni di interesse storico-artistico-archeologico
Rilassometria 1H-NMR per la caratterizzazione di legni integri e degradati
No full textLa caratterizzazione del legno riveste un particolare ruolo negli studi volti alla conservazione di manufatti lignei di interesse storico-artistico-archeologico. Le proprietà meccaniche del legno dipendono dalla specie, dal contenuto d’acqua, dalla direzione delle fibre, dalla porosità, dalla distribuzione dei pori e, in generale, da un insieme di condizioni che non sempre sono facilmente misurabili e controllabili. Di particolare interesse sono i metodi di indagine non invasivi e non distruttivi; tra questi si sta affermando la Risonanza Magnetica Nucleare (NMR) [1,2].
In questo lavoro metodi di Rilassometria 1H-NMR, messi a punto per il tessuto osseo [3], sono stati applicati allo studio di diverse tipologie lignee. I FID (Free Induction Decay) ottenuti sono la somma di due componenti: una componente approssimativamente gaussiana o “di tipo solido”, ascrivibile alle macromolecole, e una componente esponenziale o “di tipo liquido”, ascrivibile all’acqua.
Le curve di distribuzione dei tempi di rilassamento della componente longitudinale della magnetizzazione nucleare dei nuclei 1H, ottenute separatamente per le due componenti in campioni di legno stagionato, mostrano inattese regolarità, che da un lato permettono di classificare i campioni in funzione della specie e dall’altro suggeriscono fenomeni di accoppiamento e/o di scambio tra i nuclei di idrogeno dell’acqua e quelli macromolecolari. Le variazioni dei tempi di rilassamento osservate in campioni degradati possono essere rilevanti nell’ottica della determinazione di parametri atti alla valutazione dello stato conservativo di macromolecole biologiche.
Conifera, Latifoglia, Tempi di rilassamento, Macromolecole biologiche
[1] A. Maccotta. P. Fantazzini, C. Garavaglia, I. Donato, P. Perzia, M. Brai, F. Morreale, Preliminary 1H NMR study on archaeological waterlogged wood, ANNALI DI CHIMICA 95: 117-124 (2005).
[2] A. Maccotta, M. Brai, P. Fantazzini, G. Veronesi, Classificabilità di essenze lignee mediante rilassometria e imaging NMR, XCI Congresso Nazionale SIF, Catania, 26 Sett. – 1 Ott. 2005, p.192.
[3] P. Fantazzini, V. Bortolotti, R.J.S. Brown, M. Camaiti, C. Garavaglia, R. Viola, G. Giavaresi, Two 1H-NMR Methods to Measure Internal Porosity of Bone Trabeculae: by Solid-Liquid Signal Separation and by Longitudinal Relaxation, J. Appl. Phys., 95: 339-343 (2004)
Studio della cinetica di assorbimento di fluidi in mezzi porosi tramite Imaging a Risonanza Magnetica Nucleare
No full textIn questo lavoro, la tecnica di Imaging a Risonanza magnetica Nucleare (MRI) è stata impiegata per studiare in modo quantitativo, non invasivo, non distruttivo, la cinetica di assorbimento capillare di acqua in campioni di Pietra di Lecce, una biocalcarenite omogenea nella quale il fronte di bagnamento avanza pressoché piatto. MRI permette di misurare in funzione del tempo l’altezza raggiunta dal fronte in qualunque sezione interna del campione. Al fine di studiare l’anisotropia del fenomeno dovuta ad eventuali strati sedimentari, alcuni esperimenti sono stati effettuati variando l’asse principale di assorbimento (ortogonale al piano dove avviene l’assorbimento) attraverso la semplice rotazione del campione cubico. Le differenze osservate nella cinetica di assorbimento a seguito di trattamenti con prodotti idrorepellenti permettono di studiare l’efficacia dei trattamenti stessi. Le misure sono state ripetute dopo il trattamento con una resina acrilica (Paraloid B72) comunemente usata per tali trattamenti. I dati ottenuti sono stati interpretati mediante il modello di Washburn per la risalita capillare. Nell’intervallo di tempo esaminato è stata osservata la prevista dipendenza lineare dell’altezza di risalita dalla radice quadrata del tempo, sia per assorbimento dalla faccia trattata, sia per assorbimento da quella non trattata. I valori del coefficiente angolare (sorptivity, S) ottenuti nelle diverse condizioni permettono di trarre conclusioni circa l’efficacia del trattamento. Quando il litotipo è molto eterogeneo, come nel caso di una biocalcarenite proveniente da una cava nei pressi dell’area archeologica di Agrigento, MRI evidenzia un avanzamento stocastico del fluido, come confermato da immagini ottenute mediante tomografia computerizzata
Radiation quality discrimination by continuous and pulse ESR techniques
No full textThe biological damages produced by ionizing radiations in tissues and cells depend on the radiation quality, besides on the dose. The discrimination of the radiation quality, which is related to the linear energy transfer (LET), interests various fields such as radiobiology, astronautic space research, radiotherapy research and accidental dosimetry.
In this work we have applied continuous wave ESR (cw-ESR) and pulse ESR techniques to ammonium tartrate samples with the aim of developing procedures able to discriminate radiation quality whose knowledge is fundamental for rabiobiological considerations. We have chosen the ammonium tartrate because it is a promising compound for the measurement of the absorbed ionizing radiation dose [1, 2, 3]. The compound is particularly competitive to standard alanine in the detection of ionizing radiation other than high energy gamma photons, such as low energy X photons, electrons, protons, thermal neutrons.
At the same time cw-ESR and the Electron Spin Echo (ESE) decay techniques and Double Electron-Electron Resonance (DEER) can be used to obtain from average to local distributions of spins. CW-ESR is particular suited for the determination of total spin (macroscopic) concentration, whereas ESE is suited for the determination of local concentration. A new insight into the knowledge of the complex distribution of free radicals inside the dosimeters can be obtained by DEER. This technique is very useful for our purpose because it is able to measure distance between radicals in solids in the range of approximately 1.5-8 nm by analyzing the dipolar coupling between two electron spins.
In this work we analyze the spatial distributions of the free radicals produced after exposure of ammonium tartrate dosimeters to various radiation beams (21 MeV protons, 60Co γ-photons, thermal neutrons).
By measuring the differences between the local radical concentrations and the macroscopic one, and the distributions of radical-radical distances obtained with DEER, this study has given details on the differences between the distributions of radicals created by the radiation-matter energy transfer for the different ionizing radiations.
Differences and analogies are discussed in terms of differences and analogies in the LET and type of particles involved.
References
[1] S. K. Olsson, S. Bagherian, E. Lund, G. A. Carlsson, A. Lund, Appl. Radiat. Isot. 1999, 50, 95565.
[2] M. Brustolon, A. Zoleo and A. Lund, J. Magn. Reson., 1999, 137, 389-396.
[3] A. Bartolotta, M. C. D'Oca, M. Brai, V. Caputo, V. De Caro, L. I. Giannola, Phys. Med. Biol., 2001, 46, 461-471
An EPR method for discriminating radiation beams in ammonium tartrate and tooth enamel
No full textThe radiation linear energy transfer (LET), which is the energy released by ionizing radiation per path unit, arouses great scientific interest because the biological damage produced by ionizing radiation in tissues is strictly related to LET. Radiation beams with different LETs will cause different spatial energy distribution and therefore different effects inside matter.
In the last twenty years the EPR spectroscopy has become a valuable dosimetric tool. This technique allows absorbed dose measurements through the detection of free radicals produced by ionizing radiation in organic and/or inorganic compounds.
In this work we have analyzed the possibility of using the acquisition of two components (first harmonic in-phase, FH-0, and second harmonic out-of-phase, SH-90, components with respect to the modulation field) of EPR signal to discriminate the radiation quality. Studies have shown that the second harmonic absorption signal detection out-of-phase of the tooth samples could be promising for the enhancement of the tooth EPR signal [1]. In fact, the tooth EPR signal due to irradiation has large relaxation times and the SH-90 detection is very sensitive to this kind of signals. In particular, in this work we have performed a study of the dependence of the two components of the EPR signal on microwave power in order to achieve information on quality beam and on the effective radiation LET. Actually, for different LET beams the different spatial distributions of the free radicals brings about differences in the relaxation times T1 and T2 (longitudinal and transversal, respectively). These differences involve differences in the relative intensities of the two components analyzed. The analyses were carried out on samples of ammonium tartrate which is a promising compound for the measurement of the absorbed ionizing radiation dose, as it shows suitable features, such as high efficiency of radiation-matter energy transfer, and a linear relation between radiation dose [2, 3] and on tooth samples. In particular, ammonium tartrate samples were exposed to 21 MeV protons, 60Co γ-photons and thermal neutrons as radiation beams with different LET. On the other hand, the tooth samples were irradiated to UV and gamma radiation.
References
[1] V. E. Galtsev, E.V. Galtseva,Ya. S. Lebedev 1996 47, 1311-1315
[2] S. K. Olsson, S. Bagherian, E. Lund, G. A. Carlsson, A. Lund, Appl. Radiat. Isot. 1999, 50, 95565.
[3] M. Marrale, M. Brai, A. Triolo, A. Bartolotta, M. C. DOca, 2006. Radiat. Res. 166, 802809
A mathematical approach to model diffusion properties of sedimentary rocks relevant to Sicily cultural heritage.
No full textCultural heritage vestiges represent complex physical systems, able to interact with the environment through continuous exchanges of heat and fluids (water, air). In this wide context, particular relevance is assumed by transport phenomena and diffusion of pollutant, vehiculated inside the considered structure by water itself. Interaction mechanisms can be considered at various observation scales, depending on the material provenance and on its geometry and location. Involved materials are commonly constituted by porous rocks - more or less altered - belonging to geological sedimentary formations, as limestone, calcarenite and travertine. Their appreciable porosity affects significantly liquid movements; on the other hand, relevant vacuole size and geometry are likely influenced by the interactions themselves. As a matter of fact, interconnected pores increase the proper vulnerability of the materials, causing a progressive deterioration of the cultural heritage due to the close liquid-rock relations through capillarity absorption as well as gravity movements. This contributes to enlarge the whole cultural heritage risk, imposing quick and skill interventions in order to mitigate the endangerment for progressive intrusions of water-pollutant complexes. In fact, the principal aim is the protection of vestiges by means of protective products, the efficiency of which can be tested by the integration of innovative techniques and methods.
In the described circumstances, analyses of transport and diffusion seem to be fundamental for understanding the mechanism of deterioration processes and the remedial actions to prevent the decay of the cultural heritage. In this paper Authors summarize integrated experiences already performed on samples, building materials and archaeological sites of Sicily, pointing the attention to temples, tombs and other ancient remains belonging to Sicilian Aeneolithic, Greek and Baroc periods. In detail, the integrated physical techniques were X-Ray Diffractometry (XRD), X-Ray Fluorescence (XRF), Hg Porosimetry, SEM analyses, Magnetic Resonance Relaxometry (MRR), Magnetic Resonance Imaging (MRI) and X-Ray CT imaging. Applied in situ equipments were portable geophysical instruments for non-destructive prospecting. Absorption kinetics studies and internal micro-porosity surveys on samples, both through MRI and X-ray CT, were performed too, leading to preliminary interpretations of porosity and diffusion features. The entirety of measures have given a first picture of the liquid intrusion in porous rocks, well depicted by imaging elaboration procedures and sets of diagrams illustrating the physical phenomena.
A notable improvement toward the proper rock knowledge could be represented by considering the pollution source features as well as the different physical-chemical interactions of liquids/contaminants with the mean. Indeed, the phenomena are relatively complex, especially in quantifying the effects of diffusion processes. Moreover, a strong consequential inaccuracy must be considered due to insufficient geometrical considerations on the single components of the system (i.e., geological layers and/or granulometric anisotropy). Therefore, a reliable step has to be represented by analytic solutions of these mechanisms, taking into account non-stationary phenomena too, occurring in fractured rocks. Furthermore, the intrinsic properties of the considered system (sample, archaeological site, quarry) can lead to a more complicated representation of the processes, worsening the correct modeling of the liquid/pollutant flow. Thus, adopted solutions should be essentially of numerical kind, they being conditioned by the model calibration by statistical analysis between calculated and measured values. Discretization and modeling in meshes of pixels and voxels, referred to easily workable matricial numerical values, concur to the elaboration of thematic and summarized representations, with the aid of dedicated software’s, also performing a likely depiction of the cultural heritage
Sufism and Hybrid Spirituality:The Brai Performance in Cirebon-Indonesia
No full textThis article aims to discuss a Sufi-inspired traditional art and performance popular in Cirebon, the so-called “Brai”. The Brai is a traditional Islamic Sufism music popular among the Cirebonese. This traditional music combines sounds, lyrics, and dance that invite the practitioners and audiences to exercise the spiritual stages through music. The Brai performance follows the hierarchy of Sufi-state of minds and spiritual stages (suluk and raka’at). Thus, as this article argues, the Brai is a par excellence model for the entanglement between Islam and local culture. The Brai is indeed a way of the Cirebonese both to introduce Sufi-form of Islam and provides a performance where the profane arts and spiritual-Islamic Sufims are mutually entangle
Verema a l'Espartal, de ca Diego, Pinell de Brai 3/11
No full textLa família de ca Diego vermant manualment a la finca de l'Espartal, de Pinell de Brai, 31 d'agost del 2009
Interaction du bio-brai avec le coke : effet du bio-brai sur la formulation d'anode
No full textLes producteurs d'aluminium sont constamment confrontés à des défis concernant l'augmentation des coûts de production et notamment ceux liés au brai de goudron de houille. Le brai de goudron de houille est utilisé comme liant pour produire des anodes en carbone. Indépendamment des avantages techniques du brai de goudron de houille, il contient des hydrocarbures aromatiques polycycliques (HAP), connus pour être cancérigènes pour l'homme et nocifs pour l'environnement. De plus, l’augmentation phénoménale de la production d’aluminium des trente dernières années exerce une pression importante sur le marché du brai, causant une difficulté en l’approvisionnement de ce dernier. Pour surmonter ce défi, des sources de substitution au brai de goudron de houille capables de résoudre les problèmes de coût et de santé sans diminuer la qualité de l'anode sont donc d'un grand intérêt pour l’industrie. Le bio-brai produit à partir de bio-huile, pourrait être un bon candidat à cet égard. Cependant, les propriétés du bio-brai pourraient être significativement différentes de celles du brai de goudron de houille en fonction de ses origines et des conditions de son procédé. Cette étude se concentre sur la synthèse de bio-brai à partir de bio-huile dans différentes conditions de pyrolyse et la caractérisation de ses propriétés physiques et chimiques, dans le but de déterminer les conditions qui peuvent conduire à des propriétés appropriées pour la formulation d'anode. Nous avons d’abord synthétisé du bio-brai dans différentes conditions. Les bio-brais produits ont été soigneusement caractérisés afin de comprendre l’effet du procédé de fabrication sur leurs propriétés. Parmi les caractérisations typiques, on peut nommer l’analyse chimique et la détermination de la densité, du point de ramollissement, de la valeur de cokéfaction, de la teneur en insolubles de quinoléine (QI), de la teneur en HAP, de la masse moléculaire, de la viscosité, de la composition élémentaire, des structures chimiques ainsi que des mécanismes de réaction se produisant pendant le processus de pyrolyse. Ensuite, nous nous sommes concentrés sur la caractérisation de l'interaction du bio-brai avec du coke afin de comprendre son comportement et son rôle, en tant que lien, lors de la fabrication d’anode. Les informations sur la capacité de mouillage du bio-brai à la surface de la particule de coke sont d'un grand intérêt pour évaluer son utilisation éventuelle en tant que liant dans la formulation d’anode. iv Nous avons montré que la mouillabilité du bio-brai est fortement influencée par sa viscosité, sa tension superficielle, ses groupes chimiques fonctionnels de surface, sa quantité de QI et sa distribution de masse moléculaire. La bonne mouillabilité du bio-brai améliore la densification de l'anode et atténue ainsi l'effet négatif de sa faible valeur de cokéfaction sur la densité de l'anode cuite. Afin d'optimiser les propriétés du bio-brai, l'étude visant à ajuster la teneur en QI a également été effectuée afin d'améliorer ainsi sa valeur de cokéfaction en ajoutant différentes quantités d'additif (bio-char).Aluminium producers are constantly facing challenges regarding the increase in production costs including those related to coal-tar-pitch (CTP). CTP, a fossil material with carbon footprint, is used as binder to produce carbon anodes. Regardless of the technical benefits of CTP, it contains polycyclic aromatic hydrocarbons (PAHs), known to be carcinogenic for humans and detrimental to the environment. Furthermore, the escalating production capacity of aluminium during the past 3 decades exerts a considerable pressure on the pitch supply chain. To overcome this challenge, alternative sources to CTP capable of addressing the health issues and zero carbon footprint without decreasing anode quality, are thus of great interest. Bio-pitch, produced from bio-oil, could be a good candidate in this regard. However, the properties of bio-pitch could be significantly different from those of CTP depending on its origins and process conditions. This study focuses on the synthesis of bio-pitches from bio-oil under different pyrolysis conditions and characterization of its physical and chemical properties, aiming at determining the conditions which may result in suitable properties for anode formulation. We first synthesized biopitch from bio-oil under different conditions. The resulting biopitches were deeply characterized in order to understand the effect of process parameters on their properties. Among these typical characterizations are determination of density, softening point, coking value, quinoline insoluble, PAH content, molecular weight, viscosity, elemental composition, chemical structures as well as the reaction mechanisms occurring during the pyrolysis process. Then we focused on characterisation of biopitch interaction with coke in order to assess its behaviour and its role, as a binder, in anode formulation. Information on the wetting capacity of bio-pitch on the surface of coke particle is also of great interest in assessing its possible use as a renewable and environmental-friendly binder. It was shown that the wettability of bio-pitch is greatly influenced by its viscosity, surface tension, surface chemical functional groups, amount of quinoline insoluble, and molecular weight distribution. The good wettability of bio-pitch enhances the anode densification, thus mitigates the negative effect of its low coking value on the baked anode density. In order to improve the bio-pitch properties, the investigation to increase the QI content thereby to vi improve its coking value by adding different amounts of solid bio-char as an additive were also studie
Verema a l'Espartal, de ca Diego, Pinell de Brai 1/11
No full textLa família de ca Diego vermant manualment a la finca de l'Espartal, de Pinell de Brai, 31 d'agost del 2009
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