709 research outputs found
Mistici senesi
No full textMistici senesi / Piero Misciattelli. - Siena : Tip. editrice S. Bernardino, 1911
Dedica manoscritta dell\u27autore a Carlo Segre\u27: A Carlo Segre\u27, / per alta stima / Piero Misciattelli / Roma 30 nov. 1911
https://galileodiscovery.unipd.it/discovery/fulldisplay?context=L&vid=39UPD_INST:VU1&search_scope=MyInst_and_CI&tab=Everything&docid=alma99001054531020604
Production, Secretion and Biological Activity of Bacillus cereus Enterotoxins
No full textBacillus cereus behaves as an opportunistic pathogen frequently causing gastrointestinal diseases, and it is increasingly recognized to be responsible for severe local or systemic infections. Pathogenicity of B. cereus mainly relies on the secretion of a wide array of toxins and enzymes and also on the ability to undergo swarming differentiation in response to surface-sensing. In this report, the pathogenicity exerted by B. cereus toxins is described with particular attention to the regulatory mechanisms of production and secretion of HBL, Nhe and CytK enterotoxins
Le molte 'firme' degli orafi senesi
No full textIl saggio fa parte del volume (ID 33389) che inaugura la pubblicazione come serie di monografie a stampa, oltre che come numeri monografici della rivista online «Opera-Nomina-Historiae», delle sezioni ‘librarie’ del repertorio ‘Opere firmate nell'arte italiana/Medioevo’. Il progetto è volto a realizzare un corpus delle opere di ogni classe e tipologia, ‘firmate’ in latino e nei volgari italiani fra VII sec. e Gotico tardo, e prevede anche una versione in DB. La prima sezione è dedicata a “Siena e artisti senesi. Maestri orafi”.
Il saggio, preposto al catalogo – composto dai profili degli orafi, cronologicamente ordinati, e dalle schede delle relative opere firmate – , presenta innanzitutto un primo bilancio del censimento svolto per il complesso della sezione ‘Siena e artisti senesi’ del repertorio (oltre 300 attestazioni, più un centinaio per le campane, ancora in via d’indagine), sottolineando la scelta, rarissima nel complesso del progetto, di trattarla a sé.
Si propone una contestualizzazione della pratica della firma d’artista nella Siena medievale, singolarmente frequente e trasversale alle tecniche, nel quadro della ricca e variata produzione e delle dinamiche politiche artistiche del centro urbano nella stagione gotica e tardogotica.
Si formulano quindi considerazioni critiche trasversali rispetto al catalogo che segue (66 schede per 38 orafi, dal tardo Duecento, con Guccio di Mannaia, al secondo quarto del Quattrocento, con Goro di Ser Neroccio; oltre 300 illustrazioni a colori realizzate ad hoc), insistendo in primis sulla cruciale rilevanza della tradizione indiretta, data l’elevata percentuale di opere perdute. Si rileva l’eccezionalità, nel panorama europeo, di tale frequenza, continuità e omogeneità di firme di orafi, in generale e per un singolo centro (di norma menzionato nelle firme, dichiarando la provenienza ‘de Senis’ dell'artista), e se ne propongono più chiavi di lettura: incidenza di modelli di massimo prestigio (Guccio di Mannaia, calice di Niccolò IV per la Basilica Assisi); consapevolezza del carattere innovativo della produzione (nuova tecnica dello smalto traslucido) e della continuità della tradizione; status dell’oreficeria come arte-guida (relazioni con la pittura); largo successo dell’esportazione; committenze di altissimo prestigio e a raggio ‘internazionale’ (in specie, grandi reliquiari). Si propongono infine alcune ulteriori linee di ricerca sulle iscrizioni (testi, lingua: problema della formulazione della firma da parte degli artisti, in proprio o meno; forme grafiche: eventuali scritture di ‘bottega’ o d’‘autore’)
Micro-Laser Induced Breakdown Spectroscopy for recognition of chemical zoning of Ti-rich garnets in thin section.
No full textTi-rich garnets are minerals related to alkali metasomatism and magmatism of carbonatic affinity, which can be found in various undersaturated alkaline igneous rocks. The chemical composition of these minerals depends on the phys- ico-chemical growth conditions under which they formed. Thin sections of these garnets often exhibit colour zonings corresponding to chemical zonings. The innovative approach of double-pulse micro-laser-induced breakdown spectroscopy (DP- μLIBS) technique coupled with optical microscopy can be fruitfully applied to the direct quantitative analysis and character- ization in atmospheric air of the petrographic thin sections [1]. This method shows significant advantages with respect to traditional techniques used to analyze geological samples such as electron-probe microanalysis (EPMA) and scanning elec- tron microscopy-energy dispersive spectrometry (SEM-EDS), including versatility, minimal destructivity, no carbon coating, no waste production, low operating costs, rapidity of analysis and sensitivity to light elements. To validate the analytical performance of this technique, several petrographic thin sections of Ti-rich andradite garnets originated from the volcanic district of Colli Albani, Italy, were investigated. Some of these petrographic thin sections have been previously investigated by EPMA [2-4], and the analyses obtained were used to set-up the one point calibration (OPC) LIBS method in order to de- termine quantitatively the chemical composition of Ti-rich garnets. This method was then applied also to thin sections of garnet not previously investigated by conventional techniques. Several analytical spots were aligned along different direc- tions on the slices. The results obtained show that the samples studied exhibit two different types of chemical zonings. A de- crease of Ti content from core to rim of slices, which reflects the physico-chemical evolution of the growth environment (concentric zoning), and an increase of Ti in the {211} growth sectors, related to growth kinetics [3] (sector zoning). The OPC-LIBS data show a good agreement with the previous EPMA data, suggesting that the DP-μLIBS can be considered a good tool to obtain quick, fast and reliable chemical analyses of petrographic thin sections.
[1] Senesi GS, Tempesta G, Manzari P, Agrosì G, (2016) Geostandards and Geoanalytical Research 40(4): 533-541. [2] Agrosì G, Digennaro MA, Scandale E, (2001) Neues Jarhbuch fur Mineralogie Abh 176: 89-107. [3] Agrosì G, Schingaro E, Scordari F, Scandale E, Pedrazzi G, (2002) European Journal of Mineralogy 14: 785-794. [4] Agrosì G, Scandale E, Tempesta G, (2011) Periodico di Mineralogia 80(1): 89-104
Mario Bracci e il suo archivio
No full textIl fascicolo 2 dell'annata 127 (2015) di "Studi senesi" raccoglie gli atti del seminario "Mario Bracci e il suo archivio" (Siena, Aula magna storica, 16 aprile 2015). Comprende saggi di S. Fruzzetti, S. Moscadelli, G. Cianferotti, F. Colao, E. Bindi, L. Nuti e i testi degli interventi nella tavola rotonda finale di M. Barni, G. Grottanelli de' Santi, R. Bracci, G. Catoni
Micro-laser induced breakdown spectroscopy of an iron meteorite
No full textThe study has been conducted on two samples of the iron meteorite Dronino in the framework of a campaign aiming to validate planetary data on terrestrial and extra-terrestrial materials by portable techniques. The samples were studied by a portable double-pulse micro-laser-induced breakdown spectroscopy (DP-μLIBS) system coupled with optical microscopy [1]. The two fragments of Dronino have very different features, i.e. one sample is highly alterated, while the oth- er one does not show any superficial alteration but has sulphide inclusions rounded and elongated along the banding. Ac- cording to the Meteoritical Bulletin Database (MBD) Dronino meteorite belongs to an ungrouped ataxite meteorites and consists of kamacite (7.0 ± 0.5 wt% Ni and 0.75 wt% Co) and rare taenite (26.5 ± 0.5 wt% Ni and 0.35 wt% Co). The altered sample has been found in a swamp and suffered of marked weathering effects that modified the mineralogy and chemistry of the whole sample. The quantitative chemical composition measured by DP-μLIBS with One Point Calibration method [2] showed that the two samples were very different. The scanning electron microscopy (SEM) EDS analyses confirmed the DP- μLIBS results and showed that the unaltered slab consisted mainly of taenite (26.6 wt% Ni and 0.6 wt% Co), whereas kama- cite (8.2 wt% Ni and 1.1 wt% Co) was present in only one point. Differently, the altered sample consisted mainly of kamacite (6.2 wt% Ni and 1.02 wt% Co), as described in the MBD. The differences found between DP-μLIBS data and SEM results were ascribed to the heterogeneity of the sample and to the different sampling areas. In fact, the SEM chemical map showed a very fine grade texture of elongated precipitates (duplex structure) in the unaltered sample. In the altered sample DP- μLIBS indicated the presence of a Li peak on several spots, whereas Li was absent in the unaltered sample. In particular, Li is a light trace element not detectable by routinely techniques such as SEM EDS or X-ray fluorescence. The importance to evaluate Li both qualitatively and quantitatively has been already highlighted by previous studies made by ChemCam LIBS analysis on the Martian surface [3-4]. In fact, this element can provide evidence of alteration processes that might have af- fected extra-terrestrial rocks, i.e. the presence of Li in the meteorite sample would be related to the weathering processes due to aqueous solutions occurred in the swamp. [1] Senesi et al., 2016, Geostandards and Geoanalytical, Volume 40, Issue 4, Pages 533–541 [2] Cavalcanti G.H., Teixeira D.V., Legnaioli S., Lorenzetti G., Pardini L., Palleschi V., 2013, One point calibration for calibration-free laser-induced breakdown spectroscopy quantitative analysis, Spectrochim. Acta Part B, 87, 2013, 51–56. [3] Maurice et al., 2016, Journal of Analytical Atomic Spectrometry Volume 31 Number 4, Pages 823–1050 [4] Ollila et al., 2014, JGR-Planets, Volume 119, Issue 1, Pages 255–28
Monitoring of heavy metals polluted soils by Laser Induced Breakdown Spectroscopy (LIBS)
No full textFluorescence properties of humic acids interaction products with S-Triazine and Bipyridilium herbicides and their Cu complexes: A multivariate approach
No full textEffect of nerve growth factor on cultured human chondrocytes
No full textNerve growth factor (NGF) is involved in several joint diseases. It participates in nociception and neurogenic inflammation and its concentrations increase in synovial fluid and tissue from arthritis. However, data about its role in articular cartilage are scant and conflicting. This study analysed effects of different NGF concentrations on cultured human chondrocytes by evaluating cell proliferation, cell phenotype, and gene expression. The MTT test excluded an influence on cell viability. Alcian blue and S100 staining demonstrated that NGF may induce de-differentiation of the chondrocyte phenotype. Real-time PCR showed that NGF did not influence gene expression of type I, II and XI collagen, TGF-β, IGF-1 and metalloproteinase (MMP)-13, while it reduced the expression of MMP-3. These findings show that NGF may have uncertain effects in human chondrocytes. Further investigations by wider gene expression and protein synthesis analyses are required to determine how chondrocytes may be influenced by NGF
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