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In this paper, we describe an X-ray photoelectron spectroscopy (XPS) study of copper resinate, a transparent green glaze that is coloured by copper salts of resin acids. This pigment was used in Europe in the fifteenth and sixteenth centuries, but it does not seem to be a usual feature of the palette anywhere after the end of the sixteenth century, because its tendency to discolour was already widely known by artists. An essential prerequisite for the restoration of works of art is the understanding of the effects of various climatic parameters on the deterioration process. For this reason, pictorial models of copper resinate in linseed oil, capable of simulating the ancient paintings on mobile supports, were prepared and aged in a climatic chamber, under different conditions such as exposure to UV radiations, humidity and different concentration of chemical pollutants (NO2 and SO2).All the samples were investigated by XPS and the data obtained were evaluated in order to estimate aging effects as well as mechanisms of degradation. On these paint layers damage induced by X-ray irradiation was also verified. PACS 79.60.-i; 61.80.Cb; 81.40.Cd 相似文献
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Margherita Calò Alessandra Bitto Patrizia Lo Cascio Filippo Giarratana Domenica Altavilla Teresa Gervasi 《Natural product research》2018,32(10):1136-1144
The aim of the present study is to determine if Ahr ligands as PCB-126, a dioxin-like, might contribute to inhibition of the tumour suppressor p53 by promoting its degradation through proteasome-ubiquitin system (UPS). The findings show, in the presence of PCB-126, a significant increase in p53 immunoreactivity in fish compared to the control. Subsequently, there is a decrease in p53 immunoreactivity at 24 h which is maintained even at 72 h. There is also a slight decrease in ubiquitin immunoreactivity to 12 h compared to the control and a marked decrease to 24 and 72 h. It’s very important to underline as in this study we demonstrate a marked decrease in ubiquitin and p53 immunoreactivity at 24 and 72 h. Our result emphasise the need to deeply the role of this receptor in UPS regulation as potential therapeutic target for cancer treatment. 相似文献
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Amedeo Altavilla 《复变函数与椭圆型方程》2015,60(1):59-77
The theory of slice regular functions over the quaternions, introduced by Gentili and Struppa in 2007, was born on balls centred in the origin and has been extended to more general domains that intersect the real axis in a work of 2009 in collaboration with Colombo and Sabadini. This hypothesis can be overcome using the theory of stem functions introduced by Ghiloni and Perotti in 2011, in the context of real alternative algebras. In this paper, I will recall the notion and the main properties of stem functions. After that I will introduce the class of slice regular functions induced by stem functions and, in this set, I will extend the identity principle, the maximum and minimum modulus principles and the open mapping theorem. Differences will be shown between the case when the domain does or does not intersect the real axis. 相似文献
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L. Cartechini C. Miliani B.G. Brunetti A. Sgamellotti C. Altavilla E. Ciliberto F. D’Acapito 《Applied Physics A: Materials Science & Processing》2008,92(1):243-250
Investigations of the darkening phenomenon of copper resinate observed in a XV century easel painting were carried out by
X-ray absorption spectroscopy (XAS) at the GILDA beamline of the European synchrotron radiation facility (ESRF, Grenoble,
France). X-ray absorption near edge structure and extended X-ray absorption fine structure (EXAFS) measurements were collected
at the Cu K-edge on an original painting sample, as well as on fresh pigment standards and on painting models. The study was
aimed at providing structural information of the oxidation states and the local chemical environment (neighbouring atoms and
bond distances) of copper in the unaltered and blackened pigments in order to elucidate the discoloration mechanism. Complementary
information on optical and molecular properties of copper resinate were obtained by UV-vis and Fourier transform infrared
spectroscopies. EXAFS analysis evidenced that the local chemical environment of Cu in copper resinate can be described using
neutral copper acetate as a model. It consists, essentially, of bimetal Cu2+ carboxylate complexes with a distorted octahedral coordination. Such a structure is retained in the blackened pigment, although
some differences were observed. It has been found that the alteration takes place without change of the valence state of Cu(II)
ions, while the formation of the copper oxides CuO and Cu2O responsible for the embrownment is excluded. On the basis of the XAS results we deduced that discoloration of copper resinate
may be related to local modification of the copper coordination structure as evidenced by the observation of an increase of
the Cu–Cu and Cu–C distances in the EXAFS spectra.
PACS 78.70.Dm; 61.10.Ht 相似文献
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C. Altavilla E. Ciliberto S. La Delfa S. Panarello A. Scandurra 《Applied Physics A: Materials Science & Processing》2008,92(1):251-255
X-ray photoelectron spectroscopy (XPS) has been used to evaluate the reactivity of different chemical cleaning procedures
on the surface of archaeological glasses. Investigations were performed on a series of Roman glass samples coming from Sicilian
excavations. The ancient freshly fractured glass samples were subjected to different cleaning protocols such as piranha solution
(solution of sulphuric acid and hydrogen peroxide) and EDTA/ammonia and citric acid/ammonia solutions at different pH values.
The atomic concentrations of alkaline and alkaline-earth ions, measured using XPS spectra acquired at the surface of all the
samples, revealed that, in acid solution, the reactivities of the EDTA and citric acid solutions were higher than that of
the piranha solution. Moreover, in alkaline conditions, the reactivities of the chelating agent/ammonia solutions seem to
be very high and effective in taking out alkaline and alkaline-earth ions and in destroying the external glassy structure
with the formation of a silica gel thin film.
PACS 61.43.Fs; 81.65.Cf; 61.66.Fn; 82.80.Pv 相似文献
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C.?Altavilla E.?CilibertoEmail author 《Applied Physics A: Materials Science & Processing》2004,79(2):309-314
The identification and characterization of a particular pigment in an art object or in a paint layer is an important step in the history of art and technology. Moreover, the understanding of deterioration mechanisms is an essential prerequisite for diagnostics and restoration. In this work we used X-ray photoelectron spectroscopy (XPS) to study pure smalt (cobalt-based blue pigment) and smalt in a tempera media (leather-glue). XPS was used to characterize the pure pigment efficiently and to distinguish it in real paint layers. We also studied smalt in leather-glue samples aged in a climatic chamber to investigate the effects of weathering and pollutant concentration on the deterioration process of this paint system. PACS 81.05.Kf; 81.70.Jb; 82.80.Pv 相似文献
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Mathematische Zeitschrift - In the present paper we introduce the class of slice-polynomial functions: slice regular functions defined over the quaternions, outside the real axis, whose restriction... 相似文献
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