1,721,094 research outputs found
Microstructure and phase composition of bronze Montefortino helmets discovered Mediterranean seabed to explain an unusual corrosion
Full text linkTwo Monterfortino helmets, recovered in the Mediterranean seabed, show unusual features with respect to the more common helmets of the same period and found in underwater environments. Hence, they were investigated by a multi-analytical approach, which allowed us to identify the compounds constituting the helmets and to make some considerations about their metallurgy, although all the metal was converted to degradation products. The helmets, originally made in bronze, have maintained their original shape because of copper sulphides formation. The observed differences in composition between the two helmets were attributed to the position modification, of one of them, into the seabed along centuries. For the first time, a microstructural investigation permits to reconstruct the history of the aging processes involved in the total oxidation of roman bronze helmet metal
New Insight on Archaeological Metal Finds, Nails and Lead Sheathings of the Punic Ship from Battle of the Egadi Islands
Full text linkThe wreck of the Punic ship exhibited at the Archaeological Park of Lilybaeum (Marsala, Italy) is a unique example in the world. In this paper, the investigation of some metal finds (30 nails and 3 fragments of sheathings) belonging to the wreck of the Punic ship is reported. Portable X-ray fluorescence and Raman spectroscopy allowed us to identify the elements and compounds constituting them and make some deductions about their composition. X-ray diffractometry, polarised optical microscopy and scanning electron microscopy of the collected micro-samples allowed us to explain the degradation that occurred in the underwater environment
Effects of solvent-free microwave extraction on the chemical composition of essential oil of Calamintha nepeta (L.) Savi compared with the conventional production method
No full textSynthesis of yttrium aluminum garnet nanoparticles in confined environment III: Cerium doping effect
Full text linkCerium yttrium aluminum garnet (Ce:YAG, CexY3-xAl5O12) nanoparticles doped with different cerium amount were obtained by calcining the precursors synthesized via co-precipitation in w/o microemulsion for 1 h at 900 °C. The structural and morphological properties were investigated by using X-ray Diffraction (XRD), Infrared Spectroscopy (IR) and Transmission Electron Microscopy (TEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS) in order to investigate the effect of doping level on formation and microstructure of obtained nanoparticles. It was found that the composition of the final products strongly depends on the concentration of cerium. The formation of single YAG phase was observed only at 0.5% cerium. For other concentrations, a mixture of YAG and yttria phases was obtained indicating an effect of the cerium on stabilization of sesquioxide phase. Optical properties of the single phase powder were also investigated in details
Archaeometric study of execution techniques of white Attic vases: the case of the Perseus crater in Agrigento
No full textThe white ground crater by the Phiale Painter (450–440 BC) exhibited in the “Pietro Griffo” Archaeological Museum in Agrigento (Italy) depicts two scenes from Perseus myth. The vase is of utmost importance to archaeologists because the figures are drawn on a white background with remarkable daintiness and attention to detail. Notwithstanding the white ground ceramics being well documented from an archaeological and historical point of view, doubts concerning the compositions of pigments and binders and the production technique are still unsolved. This kind of vase is a valuable rarity, the use of which is documented in elitist funeral rituals. The study aims to investigate the constituent materials and the execution technique of this magnificent crater. The investigation was carried out using non-destructive and non-invasive techniques in situ. Portable X-ray fluorescence and Fourier-transform total reflection infrared spectroscopy complemented the use of visible and ultraviolet light photography to get an overview and specific information on the vase. The XRF data were used to produce false colour maps showing the location of the various elements detected, using the program SmART_scan. The use of gypsum as the material for the white ground is an important result that deserves to be further investigated in similar vases
I ‘vasi di Centuripe’: per un approccio integrato
No full textIl contributo intende evidenziare le prospettive di un approccio interdisciplinare integrato allo studio della ceramica policroma
“di Centuripe”. Dagli inizi del XX secolo, tale classe ha riscosso ampio apprezzamento per le sue delicate pitture e la
ricchezza di ornamenti a rilievo applicati (dipinti e dorati) che abbelliscono i vasi, rendendoli pressoché inutilizzabili nella
pratica per scopi funzionali, ma altamente efficaci come doni funerari in antico, e oggi come pezzi di grande impatto per
commercianti di antichità e collezionisti moderni. Data la piaga, diffusa fino a tempi recenti, degli scavi clandestini, dei “restauri”
arbitrari e delle falsificazioni, i vasi di Centuripe necessitano di analisi scientifiche appropriate mirate a confermare
sia l’autenticità degli oggetti che delle loro figurazioni dipinte, o anche di singoli dettagli (spesso aggiunti, rifatti o inventati
dal “restauratore”).
Due vasi di Centuripe di alta qualità, esposti nel Museo Archeologico Regionale “A. Salinas” di Palermo, sono stati oggetto
di un’indagine attraverso tecniche spettroscopiche complementari (XRF e riflettanza totale FTIR), effettuate con strumentazione
portatile. Le analisi hanno confermato la tecnica a tempera delle pitture, mostrando la presenza di pigmenti antichi
ma anche moderni. Questi ultimi attestano dei “restauri” non documentati che hanno alterato lo stile originario e in parte il
disegno delle figure (soprattutto nella pyxis), pur conservando l’iconografia generale di partenza.
Uno dei risultati di maggior interesse è l’individuazione di due fasi del solfato di calcio nello strato di preparazione delle
pitture: la presenza di bassanite fa riconoscere la tecnica di esecuzione antica, denotando una cottura a bassa temperatura
preliminare alla vera e propria dipintura realizzata a crudo, a tempera. Al contrario, la presenza di gesso in altri punti rivela
un intervento successivo: essa coincide del resto con i ritocchi o le tracce di pigmenti moderni individuati.
La palette cromatica dei due vasi non è identica, così come lo stile e le decorazioni secondarie, ciò che viene a contraddire
l’ipotesi avanzata da P. W. Deussen secondo cui i due esemplari oggi a Palermo e altri due acquisiti dallo stesso trafficante,
ora nel Metropolitan Museum di New York, sarebbero appartenuti alla stessa tomba. Il lebes gamikos si contrassegna in
particolare per l’uso di pigmenti più rari, come il cinabro e possibilmente l’azzurrite, e per la qualità del disegno.
Gli stessi effetti cromatici non sono semplicemente legati al gusto, ma insieme all’iconografia e alla costruzione d’insieme
del vaso concorrono alla realizzazione di un oggetto di corredo prestigioso e di grande valore simbolico, che suggerisce una
qualche speranza o auspicio di immortalità per il defunto.The paper aims at showing the usefulness of an interdisciplinary approach to the study of the polychromatic “Centuripe” ware.
Since early 20th century, such class has been appreciated for its fancy paintings and the richness of the applied relief decorations
(painted and gilded) that embellish the vases, making them unsuitable for an utilitarian use, but impressive as funerary gifts and,
nowadays, as show pieces for antiquarians and collectors. Due to the spreading, till recent times, of illicit excavations, arbitrary
restorations and forgeries, the Centuripe vases need a scientific investigation in order to confirm the authenticity both of the
whole objects and paintings, and of single details (often added or reshaped by the “restorer”).
Two fine Centuripe vases, exhibited in the Archaeological Museum “A. Salinas” of Palermo, were analyzed using complementary
portable XRF and Total Reflectance FTIR spectroscopies. The analyses confirmed the tempera technique, and showed the
presence of both ancient and modern pigments. These latter testify some unrecorded “restorations” which altered the original
style and partly the outlines of the figures (above all in the pyxis), while the general iconography was preserved.
One of the most interesting results was the identification of two phases of the calcium sulfate in the stratum underlying the
paintings: the presence of bassanite reveals the ancient technique of execution, implying that this layer underwent a low temperature
firing, after which the true tempera painting was laid. On the contrary, the presence of gypsum in other points reveals
a later intervention; it coincides with the retouches or the traces of modern pigments.
The palette of the two vases is not identical, just like the style and the secondary decorations, contradicting the hypothesis made
by P.W. Deussen, according to which these and two further vases found by the same dealer (now in the Metropolitan Museum
of New York) belonged to the same tomb. The lebes gamikos stands out for the use of rarer pigments, like cinnabar and probably
azurite, and for the quality of the drawing.
The chromatic effects themselves are not merely questions of taste, but cooperate with the iconography and the overall design in
creating a prestigious gift and of great symbolic value, suggesting a hope of immortality for the dead
Preparation of Nd:YAG Nanopowder in a Confined Environment
No full textNanopowder of yttrium aluminum garnet (YAG, Y3Al5O12) doped with neodymium ions (Nd:YAG) was prepared
in the water/cetyltrimethylammonium bromide/1-butanol/n-heptane system. Aluminum, yttrium, and neodymium
nitrates were used as starting materials, and ammonia was used as a precipitating agent. Coprecipitate hydroxide
precursors where thermally treated at 900 °C to achieve the garnet phase. The starting system with and without
reactants was characterized by means of the small-angle neutron scattering technique. The system, without reactants,
is constituted by a bicontinuous structure laying near the borderline with the lamellar phase region. The introduction
of nitrates stabilizes the bicontinuous structure, while the presence of ammonia induces a transformation from the
bicontinuous phase to a lamellar phase. Nd:YAG nanopowder was characterized by wide-angle X-ray scattering,
transmission electron microscopy, gas adsorption, and photoluminescence spectroscopy. By comparison with a sample
prepared by the conventional coprecipitation method, the obtained Nd:YAG nanopowder is constituted by smaller
crystalline nanoparticles showing a lower tendency to agglomerate. In addition, the nanoparticles present a welldefined
spherical shape. Photoluminescence spectroscopy confirms that the doping Nd3+ ions substitute Y3+ ions in
the YAG crystalline lattice. The Nd3+ lifetime value, obtained from the luminescence decay curves, was 286 ( 10
ís, higher than the single-crystal value (255 ís) and much higher than the nanopowder value obtained by the conventional
coprecipitation method (75 ís)
Loading and release of the complex [Pt(DTBTA)(DMSO)Cl]Cl·CHCl3 with the 2,2′-dithiobis(benzothiazole) ligand into mesoporous silica and studies of antiproliferative activity on MCF-7 cells
Full text linkSynthetic delivery systems have great potential for overcoming problems associated with systemic toxicity that accompanies chemotherapy with the use of cisplatin and family of platinum anticancer drugs. Mesoporous silicates have been studied in context of drug delivery and drug targeting. In this paper we report the studies of loading and release of a platinum complex, [Pt(DTBTA)(DMSO)Cl]Cl∙CHCl3 (1) where DTBTA = 2,2′-dithiobis(benzothiazole), that was recently synthesized and structurally characterized. Evaluation in vitro of antitumor activity against a human breast cancer cell line (MCF-7) showed a very potent activity of complex(1). Therefore, we thought to incorporate this compound into MCM41 mesoporous silica and into analogous support functionalized with amino groups (MCM41-NH2). The complex(1) encapsulation efficiency % (EE%) in MCM41 and in MCM41-NH2, respectively, was evaluated by using UV–Vis spectroscopy. The porosimetry and IR spectra confirmed that the drug was within the pores in MCM-41 and that the complex(1) binds MCM41-NH2 with the aminopropyl functional groups of the mesoporous channels, respectively. The study of release was performed by using UV–Vis spectroscopy at 37 ± 1 °C in 0.1 M phosphate buffer solution (PBS) having pH 7.4 to simulate the physiological pH of blood. In order to investigate the efficacy of MCM-41/complex(1) and MCM41-NH2/complex(1) conjugates, we have measured their ability to kill cancer cells of MCF-7 (human breast cancer). MTT test and cytofluorimetric assay of exposure of phosphatidylserine to the outer membrane were carried out to measure cytotoxicity and apoptosis induced by MCM41/complex(1) and MCM41-NH2/complex(1). The investigated systems were very efficient for pharmaceutical controlled release and a promising agent for combination therapies
Synthesis and antibacterial activity of iron-hexacyanocobaltate nanoparticles
Full text linkThis paper deals with the synthesis and characterization of iron-hexacyanocobaltate (FeHCC) and its antibacterial properties. The nanoparticles were prepared by a facile co-precipitation technique. Crystal structure, particle morphology, and elemental composition were determined using X-ray Powder Diffraction, X-ray fluorescence spectroscopy, Transmission Electron Microscopy (TEM), and Infrared Spectroscopy (IR). The antibacterial activity of the FeHCC nanoparticles was tested against Escherichia coli and Staphylococcus aureus as models for Gram-negative and Gram-positive bacteria, respectively, by bacterial counting method and microscopic visualization (TEM, FEG-SEM, and fluorescence microscopy). The results showed that the FeHCC nanoparticles bind to the bacterial cells, inhibit bacterial growth in a dose- and time-dependent manner, inducing a loss of the membrane potential, the production of reactive oxygen species and the release of macromolecules (nucleic acids and proteins) in the extracellular environment. To the best of our knowledge, this is the first study reporting the antimicrobial effects of metal-hexacyanometallates suggesting practical uses of these materials in different areas, such as self-cleaning surfaces or food packaging
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