92 research outputs found

    Mejora de sensores vítreos sol-gel para la conservación preventiva de materiales históricos frente a la acidez

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    [ES] Los sensores a base de recubrimientos vítreos sol-gel dopados con ácido 2[4-(dimetil-amino) fenilazo] benzoico son capaces de cambiar su absorción óptica cuando se someten a distintas concentraciones de iones H3O+ y OH-. La respuesta de los sensores en ensayos de campo se estudió en Cracovia (Polonia) variando el procedimiento normal de uso, con el fin de mejorar su respuesta. Se midieron tanto los parámetros ópticos de los sensores como las condiciones ambientales (temperatura, humedad, presión y concentraciones de SO2 y de NOx). La respuesta de los sensores se analizó en términos de los cambios de su absorción visible. Dichos cambios se deben a reacciones locales de neutralización que tienen lugar en la superficie de los sensores, debido al efecto conjunto de los contaminantes de carácter ácido y a la humedad ambiental. Se establecieron correlaciones entre la concentración del contaminante principal (SO2) y la respuesta de los sensores para elaborar una calibración directa entre la absorción óptica y el pH ambiental. Los sensores pueden detectar y evaluar la acidez ambiental, así como alertar sobre la concentración de contaminantes ácidos que pueden dañar a la mayoría de los materiales históricos.[EN] Sensors based on sol-gel glassy coatings doped with 2[4-(dimethyl-amino) phenylazo] benzoic acid are able to change their optical absorption when they are submitted to different concentration of H3O+ and OH-. The sensors behaviour in field tests was studied in Cracow (Poland), varying the normal procedure of operation to improve their response. Both the sensors optical parameters and the environmental conditions (temperature, humidity, pressure, SO2 and NOx concentrations) were measured. The sensors response was analysed in terms of their visible absorbance changes, which are due to local neutralisation reactions in the sensors surface by the join effect of acid pollutants and humidity. Correlations between the main acid pollutant (SO2) concentration and the sensors response are established to provide a relation between the optical absorption and the environmental pH. The sensors are able to detect and monitorise environmental acidity, as well as to alert on the pollutant concentration that may damage most of the historical materials.The authors wish to acknowledge bilateral Polish-Spanish project Ref. PAN-CSIC 2003PL0011, European Marie Curie project Ref. MERG-CT-2004-516436 and Spanish project Ref. CICYT-MAT-2003-03231 for financing support. N.C. acknowledges CSIC-ESF for an I3P postdoctoral contract.Peer reviewe

    Extending the tephra and palaeoenvironmental record of the Central Mediterranean back to 430 ka: A new core from Fucino Basin, central Italy

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    Here we present the first tephrostratigraphic, palaeomagnetic, and multiproxy data from a new ∼98 m-deep sediment core retrieved from the Fucino Basin, central Italy, spanning the last ∼430 kyr. Palaeoenvironmental proxy data (Ca-XRF, gamma ray and magnetic susceptibility) show a cyclical variability related to interglacial-glacial cycles since the Marine Isotope Stage (MIS) 12-MIS 11 transition. More than 130 tephra layers are visible to the naked eye, 11 of which were analysed (glass-WDS) and successfully correlated to known eruptions and/or other equivalent tephra. In addition to tephra already recognised in the previously investigated cores spanning the last 190 kyr, we identified for the first time tephra from the eruptions of: Tufo Giallo di Sacrofano, Sabatini (288.0 ± 2.0 ka); Villa Senni, Colli Albani (367.5 ± 1.6 ka); Pozzolane Nere and its precursor, Colli Albani (405.0 ± 2.0 ka, and 407.1 ± 4.2 ka, respectively) and Castel Broco, Vulsini (419–490 ka). The latter occurs at the bottom of the core and has been 40Ar/39Ar dated at 424.3 ± 3.2 ka, thus providing a robust chronological constrain for both the eruption itself and the base of the investigated succession. Direct 40Ar/39Ar dating and tephra geochemical fingerprinting provide a preliminary radioisotopic-based chronological framework for the MIS 11-MIS 7 interval, which represent a foundation for the forthcoming multiproxy studies and for investigating the remaining ∼110 tephra layers that are recorded within this interval. Such future developments will contribute towards an improved MIS 11-MIS 7 Mediterranean tephrostratigraphy, which is still poorly explored and exploited

    Model Fusion for the Compatibility Verification of Software Components

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    Similarly as in earlier work on component compatibility, the behavior of components is specified by component interface languages, defined by labeled Petri nets. In the case of composition of concurrent components, the requests from different components can be interleaved, and - as shown earlier - such interleaving can result in deadlocks in the composed system even if each pair of interacting components is deadlock–free. Therefore the elements of a component–based system are considered compatible only if the composition is deadlock–free. This paper formally defines model fusion, which is a composition of net models of individual components that represents the interleaving of interface languages of interacting components. It also shows that the verification of component compatibility can avoid the exhaustive analysis of the composed state space

    Pleistocene tephrostratigraphy and palaeoclimatology in the central Mediterranean region: ongoing research in Fucino Basin (central Apennines, Italy)

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    Palaeoclimatic records spanning beyond the radiocarbon range generally derive their chronologies from orbital tuning strategies. These chronologies can introduce a priori assumptions that are difficult to test and, possibly, circular arguments in palaeoclimatic reconstructions. We elaborate two high-resolution, multi-proxy and tephrochronologically-constrained records (F1-F3 and F4-F5) of past environmental and climatic changes in the central Mediterranean region. We perform geochemical (X-ray fluorescence scanning, carbon, nitrogen and sulphur elemental analysis through combustion), isotopic (C and O stable isotope mass spectrometry on bulk carbonates and organic matter), mineralogical (X-ray powder diffraction) and grain-size analyses on lacustrine marls recovered from palaeolake Fucino (Abruzzo, central Italy). Lacustrine sediments were acquired during two scientific drilling campaigns (F1-F3 and F4-F5) interesting the first ca. 85 m of the 1 km-thick and 2 Ma-old Fucino sedimentary succession. We make use of detailed tephrostratigraphic and tephrochronological frameworks to produce robust and independent chronologies based on new and published 40Ar/39Ar and 14C dating of tephra layers. On the basis of our chronologies, the F1-F3 and F4-F5 records continuously span over the last two glacial-interglacial cycles and over the last five glacial-interglacial cycles, respectively. We combine our geological data into proxies for catchment- and regional-scale environmental processes. Our proxy time-series depict prominent orbital and sub-orbital environmental changes that can be tracked in other lacustrine, marine and speleothem records across the Mediterranean and North Atlantic regions. Thanks to tephrostratigraphic correlations and chronological matching, we produce spatially coherent palaeoclimatic reconstructions recognising a complex interplay between regional environmental processes and broad-scale climatic events. We highlight strong orbital forcing for past climate changes

    Mediterranean winter rainfall in phase with African monsoons during the past 1.36 million years

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    Mediterranean climates are characterized by strong seasonal contrasts between dry summers and wet winters. Changes in winter rainfall are critical for regional socioeconomic development, but are difficult to simulate accurately1 and reconstruct on Quaternary timescales. This is partly because regional hydroclimate records that cover multiple glacial–interglacial cycles2,3 with different orbital geometries, global ice volume and atmospheric greenhouse gas concentrations are scarce. Moreover, the underlying mechanisms of change and their persistence remain unexplored. Here we show that, over the past 1.36 million years, wet winters in the northcentral Mediterranean tend to occur with high contrasts in local, seasonal insolation and a vigorous African summer monsoon. Our proxy time series from Lake Ohrid on the Balkan Peninsula, together with a 784,000-year transient climate model hindcast, suggest that increased sea surface temperatures amplify local cyclone development and refuel North Atlantic low-pressure systems that enter the Mediterranean during phases of low continental ice volume and high concentrations of atmospheric greenhouse gases. A comparison with modern reanalysis data shows that current drivers of the amount of rainfall in the Mediterranean share some similarities to those that drive the reconstructed increases in precipitation. Our data cover multiple insolation maxima and are therefore an important benchmark for testing climate model performance

    Colonoscopic-Assisted Laparoscopic Wedge Resection for Colonic Lesions A Prospective Multicenter Cohort Study (LIMERIC-Study)

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    Objective: The aim of this study was to evaluate the safety and efficacy of a modified CAL-WR. Summary Background Data: The use of segmental colectomy in patients with endoscopically unresectable colonic lesions results in significant morbidity and mortality. CAL-WR is an alternative procedure that may reduce morbidity. Methods: This prospective multicenter study was performed in 13 Dutch hospitals between January 2017 and December 2019. Inclusion criteria were (1) colonic lesions inaccessible using current endoscopic resection techniques (judged by an expert panel), (2) non-lifting residual/recurrent adenomatous tissue after previous polypectomy or (3) an undetermined resection margin after endoscopic removal of a low-risk pathological T1 (pT1) colon carcinoma. Thirty-day morbidity, technical success rate and radicality were evaluated. Results: Of the 118 patients included (56% male, mean age 66 years, standard deviation +/- 8 years), 66 (56%) had complex lesions unsuitable for endoscopic removal, 34 (29%) had non-lifting residual/recurrent adenoma after previous polypectomy and 18 (15%) had uncertain resection margins after polypectomy of a pT1 colon carcinoma. CAL-WR was technically successful in 93% and R-0 resection was achieved in 91% of patients. Minor complications (Clavien-Dindo i-ii) were noted in 7 patients (6%) and an additional oncologic segmental resection was performed in 12 cases (11%). Residual tissue at the scar was observed in 5% of patients during endoscopic follow-up. Conclusions: CAL-WR is an effective, organ-preserving approach that results in minor complications and circumvents the need for major surgery. CAL-WR, therefore, deserves consideration when endoscopic excision of circumscribed lesions is impossible or incomplete.Cellular mechanisms in basic and clinical gastroenterology and hepatolog
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