462 research outputs found
K-edge Radiography and applications to Cultural Heritage
No full textThe present work of thesis is focused on application of X-ray K-edge
technique to paintings.
This technique allows one to achieve a topographic map of a pigment on the
whole surface of the painting. The digital acquisition of radiographic images
by using monochromatic X-ray beams allows to take advantage of the sharp
rise of X-ray absorption coefficient of the elements, the K-edge discontinuity.
Working at different energies, bracketing the K-edge peak, allows recognition
of the target element.
The K-edge radiography facility installed at Larix Laboratory, at Department
of Physics in Ferrara, consists of a quasi-monochromatic X-ray beam obtained
via Bragg diffraction on a mosaic crystal from standard X-ray source.
In this work the K-edge technique and the facility used are illustrated. A
characterization of the monochromatic beams in the energy range 7-40 KeV
range and the elemental mapping on pictorial layers obtained are presented.
At the end, a transportable facility for digital radiography is presented and
some radiographic analysis of works of art performed are shown
Synthesis and Crystal Structure of Tris(4-nitrophenyl isocyanide)bis(diethyl phenylphosphonite)cobalt(I) Perchlorate
No full textThe syntheses of five-coordinate cobalt(I) complexes of the type [Co(4-NO2C6H4NC)5-x(PhP(OEt)2)x]ClO4 (x = 2 or 3) obtained by reaction at room temperature of 4-nitrophenyl isocyanide with cobalt(II) chloride and diethyl phenylphosphonite is reported. The compounds were characterized on the basis of their chemical and physical properties (conductivities and infrared, electronic, and 1H NMR spectra). The crystal and molecular structure of tris(4-nitrophenyl isocyanide)bis(diethyl phenylphosphonite)cobalt(I) perchlorate, [Co(4-NO2C6H4NC)3(PhP(OEt)2)2]ClO4, has been determined by single-crystal x-ray analysis and refined, with full-matrix least squares using anisotropic temperature parameters for all atoms, to R = 0.072 on F2. The crystals are monoclinic, space group P21/c (C2h5), with a = 13.085 (5) Å, b = 10.826 (4) Å, c = 33.019 (8) Å, β = 91.92 (3)°, and Z = 4. The coordinated polyhedron around the cobalt atom has the shape of a slightly distorted trigonal bipyramid with isocyanide ligands in the equatorial positions. The average Co-C and Co-P distances (1.80 and 2.175 Å, respectively) clearly indicate strong double-bond character. Distortions around the phosphorus atoms are compared with those found in Ni(II) and Fe(II) complexes with the same phosphonite ligand and correlated to the M-P ir interaction. © 1976, American Chemical Society. All rights reserved
Arenediazonium Complexes of Cobalt(I): Synthesis and Properties
No full textArenediazonium complexes of cobalt(I) of the type [Co(RN2)L4] [BPh4]2 [L = P(OEt)2Ph, P(OEt)3, or P(OMe)3; R = 4-CH3C6H4, 3-CH3C6H4, 2-CH3C6H4, C6H5, 4-CH3OC6H4, 4-ClC6H4, or 4-FC6H4] have been prepared; their characterization by i.r., 1H, and 31P-{1H} n.m.r. spectra is reported. Reactivity with π-acceptor ligands such as CO, NO, isocyanide, and phosphite is also described. Finally, the reaction of the arenediazonium complexes with chloride ions affording the cobalt(II) derivatives [CoClL4]+ has been investigated; the function of RN2 as an oxidizing agent in this reaction is also discussed
Urotensin-II and its receptor (UT-R) are expressed in rat brain endothelial cells, and urotensin-II via UT-R stimulates angiogenesis in vivo and in vitro
No full textUrotensin-II (UII), along its receptor UT-R, is widely expressed in the cardiovascular system, where it exerts regulatory actions under both physiological and pathological conditions. Real-time PCR and immunocytochemistry demonstrated the expression of UII and UT-R as mRNA and protein in rat neuromicrovascular endothelial cells (NECs). UII did not affect the proliferation rate of cultured NECs, but exerted a strong angiogenic action in both an in vitro assay on Matrigel and an in vivo assay on chorioallantoic membrane. The angiogenic effect of UII was similar to that of FGF-2, and was abolished by the UT-R antagonist Palosuran. Collectively, our findings allow us to include UII in the group of cytokines (e.g. endothelin-1 and adrenomedullin), which are expressed in endothelial cells and exert a pro-angiogenic effect acting in an autocrine-paracrine manner
Preparation of Half-sandwich Alkoxycarbene Complexes of Osmium(II)
No full textAlkoxy-alkylcarbene complexes [OsCl{=C(OR′)CH 2R′′}(η6-p-cymene)L]BPh4 (1-4) [R′ = Me, Et; R′′ = Ph, p-tolyl, But; L = P(OMe)3, P(OEt)3, PPh(OEt)2, PPh 2OEt] were prepared by allowing dichloro compounds OsCl 2(η6-p-cymene)L to react with terminal alkyne R′′C=CH in alcohol. Ethoxy-methylcarbene [OsCl{=C(OEt)CH 3}(η6-p-cymene)L]BPh4 (5) was also prepared from reaction with trimethylsilyl acetylene. A reaction path for the formation of compounds 1-5, involving the nucleophilic attack of alcohol on intermediate vinylidene complexes, is discussed. Acetylide derivatives OsCl(C=CAr) (η6-p-cymene)L (6, 7) [Ar = Ph, p-tolyl; L = P(OMe)3, P(OEt)3, PPh(OEt)2] were prepared by reacting dichloro compounds OsCl2(η6-p-cymene)L with lithium acetylide (Li+[ArC=C]-) in thf. Protonation reaction with Brønsted acids of 6 and 7 led to vinylidene cations [OsCl{=C=C(H)Ar} (η6-p-cymene)L]+. Complexes OsCl2(η 6-p-cymene)L also reacted with both PhC=CH and (CH3) 3SiC=CH in the presence of H2O to give alkyl-carbonyl derivatives [Os(η1-CH2Ph)(CO)(η6-p- cymene)L]BPh4 (8) and [Os(η1-CH3)(CO) (η6-p-cymene)L]BPh4 (9). The complexes were characterized spectroscopically (IR and 1H, 13C, 31P NMR) and by X-ray crystal structure determinations of [OsCl{=C(OEt)CH2Ph}(η6-p-cymene){PPh(OEt) 2}]BPh4 (1c), [OsCl{=C(OEt)CH2Ph} (η6-p-cymene)(PPh2OEt)]BPh4 (1d), and [Os(η1-CH2Ph)(CO)(η6-p-cymene){PPh(OEt) 2}]BPh4 (8c). © 2011 American Chemical Society
Electrochemical Behaviour of Dinitrosylbis(triethyl phosphite)cobalt(I) Tetraphenylborate in Acetonitrile
No full textThe electrochemical behaviour of the complex [Co{P(OEt)3}2(NO)2][BPh4] has been studied in acetonitrile, using platinum and mercury electrodes. It undergoes two subsequent reduction processes and a single oxidation process. In particular, the less cathodic one-electron reduction leads to the formation of the corresponding neutral species which is fairly stable in carefully deaerated solution
Reactivity of the Hydride [CoH{P(OEt)2Ph}4] with RN2+ (R = aryl), NO+, and H+ Cations: Preparation and Properties of New Cobalt Complexes. Measurements of T1 for [CoH{P(OEt)2Ph}4] and [CoH2{P(OEt)2Ph}4]BPh4
No full textThe reaction of [CoH{P(OEt)2Ph}4] with RN2+ (R = 4-CH3C6H4) affords the paramagnetic cationic hydride [CoH{P(OEt)2Ph}4]+, with NO+ the dinitrosyl cation [Co(NO)2{P(OEt)2Ph}2]+, and with HBF4·Et2O the cationic dihydride [CoH2{P(OEt)2Ph}4]+. Characterization of the complexes by i.r., e.s.r., and variable-temperature 1H and 31P-{1H} n.m.r. spectra is described. Variable-temperature 1H n.m.r. T1 measurements at 80, 200, and 400 MHz for both [CoH{P(OEt)2Ph}4] and [CoH2{P(OEt)2Ph}4]BPh4 are also reported. The reactivity of the cationic hydrides with CO, RNC, NO, I2, and RN2+ was investigated and the new cations [Co(CNR)2{P(OEt)2Ph}3]+ (R = 4-CH3C6H4, 4-CH3OC6H4, or 4-ClC6H4) and [CoH(I){P(OEt)2Ph}4]+ synthesized. The unstable intermediate [CoH(NO){P(OEt)2Ph}4]+ [ν(NO) at 1 680 cm-1] was also detected
Estudio de la Primera y Segunda Parte de Pedro de Cieza de León: la Crónica del Perú y el Señorío de los incas
No full textThe Pedro de Cieza de León’s Crónica del Perú belongs to those Indian chronicles that were written before the arrival of the viceroy Toledo in the Peru. Only the Primera Parte was published when the author was still in life, in the 1553.
The purpose of the thesis is to show the influence practiced by Cieza de León during the XVI century, inside the Hispanic-American world and out, especially in Italy. It is mainly composed of three parts: in the first one I analyze the influence that the Primera Parte de la Crónica of Perú has had on the Comentarios reales de los incas of Garcilaso de la Vega to see how and why Cieza de León has been «copied», apart from the recognition of his authority. The second section studies the translation to the Italian of the Primera Parte completed by a Spanish translator that around the half of the s. XVI was living in the Vatican, Agustín de Cravaliz. The first edition went out in Rome, in the printing of the Fratelli Dorico, or Dorici. It was the base of further editions that had been published in the Republic of Venice from the 1556 to the 1576. In this section I analyze in detail how the Cravaliz translated from Spanish to Italian, considering that he managed a language which was not his mothertongue. I will identify and I will comment the different translation actions. In the end, the third part refers to the paleografic transcription of the Señorío de los incas, which is based on the manuscript that is currently conserved at the Biblioteca Apostolica Vaticana that was discovered at the end of the Seventies of the XIX century. I will introduce the criterions of edition together with the transcription as faithful as possible to the native text.La Crónica del Perú di Pedro de Cieza de León appartiene a quella corrente di cronache indiane che furono scritte prima dell’arrivo del vicerè Toledo in Perù. Solamente la Primera Parte fu pubblicata quando l’autore era ancora in vita, nel 1553.
La finalità della tesi è dimostrare l’influenza esercitata da Cieza de León durante il s. XVI, all’interno del mondo ispano-americano e fuori, soprattutto in Italia. Si compone principalmente di tre parti: nella prima analizzo l’influenza che la Primera Parte de la Crónica del Perú ha avuto sui Comentarios reales de los incas di Garcilaso de la Vega per vedere fino a che punto Cieza de León è stato «copiato» e a che scopo, a parte quello del riconoscimento della sua autorità. La seconda sezione studia la traduzione all’italiano della Primera Parte compiuta da uno spagnolo che attorno alla metà del s. XVI si trovava in Vaticano, Agustín de Cravaliz. La prima edizione uscì a Roma, nella stamperia dei Fratelli Dorico, o Dorici. Essa fu alla base di ulteriori edizioni pubblicate nella Repubblica di Venezia dal 1556 al 1576. In questa sezione analizzo dettagliatamente come il Cravaliz passò dallo spagnolo all’italiano, considerando che tradusse a una lingua che non era la sua. Identificherò e commenterò le differenti azioni traduttive. Da ultimo, la terza parte si riferisce alla trascrizione paleografica del Señorío de los incas, che si basa sul manoscritto che si trova attualmente presso la Biblioteca Apostolica Vaticana che fu scoperto alla fine degli anni Settanta del s. XIX. Presenterò i criteri di edizione assieme alla trascrizione il più fedele possibile al testo originario
Exploring the Use of Cohesive Devices in Dementia within an Elderly Italian Semi-spontaneous Speech Corpus
No full textThe study of language disruption in dementia, aimed at individuating which features correlate with cognitive impairment, is a growing area in computational linguistic research. Still, it needs a further development in analyzing some discourse phenomena that also undergo deterioration, and can help expand our understanding of dementia-related speech and refine automatic tools. This paper explores the discourse property of cohesion by investigating three types of cohesive devices: reference, lexical iteration, and connectives. Ten features related to these categories have been defined and automatically extracted from an Italian corpus of semi-spontaneous speech collected from dementia patients and healthy controls. Some of the designed features have proven significant for the binary classification of the two groups and further quantitative analysis highlight interesting differences in the use of cohesive devices, that seem to be associated with cognitive decline
Reactions of IrHCl2(PPh3)2{P(OEt)3} with Organic Azides: Formation of Aminophosphonium Salts
No full textAminophosphonium salts [Ph3PN(H)R]BPh4 (1) [R = C6H5CH2 (1a), 4-CH3C6H4CH2 (1b), C6H5 (1c)] were obtained by allowing hydride IrHCl2(PPh3)2{P(OEt)3} to react first with triflic acid and then with the organic azide RN3. The compounds were characterized spectroscopically and by X-ray crystal structure determination of [Ph3PN(H)CH2C6H4-4-CH3]BPh4 (1b). A reaction path for the formation of aminophosphonium cations is also proposed
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