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

[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

Sedimentological processes and environmental variability at Lake Ohrid (Macedonia, Albania) between 640 ka and present day

Lake Ohrid (FYROM, Albania) is thought to be more than 1.2 million years old and hosts more than 200 endemic species. As a target of the International Continental Scientific Drilling Program (ICDP), a successful deep drilling campaign was carried out within the scope of the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) project in 2013. Here, we present lithological, sedimentological, and (bio-)geochemical data from the upper 247.8 m of the overall 569 m long DEEP site sediment succession from the central part of the lake. According to an age model, which is based on nine tephra layers (1st order tie points), and on tuning of biogeochemical proxy data to orbital parameters (2nd order tie points) and to the global benthic isotope stack LR04 (3rd order tie points), respectively, the analyzed sediment sequence covers the last 640 ka

Shuffle–based verification of component compatibility

An extension of earlier work on component compatibility is described in this paper. Similarly as before, the behavior of components is specified by component interface languages, and the shuffle operation is introduced to represent possible interleavings of service requests that originate at several concurrent components. The paper shows that the verification of component compatibility is possible without the exhaustive analysis of the state space of interacting components. Exhaustive analysis of state spaces was the basis of earlier approaches to compatibility verification

Model Fusion for the Compatibility Verification of Software Components

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

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

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

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

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

Service Renaming in Component Composition

In component-based systems, the behavior of components is usually described at component interfaces and the components are characterized as requester (active) and provider (reactive) components. Two interacting components are considered compatible if all possible sequences of services requested by one component can be provided by the other component. This concept of component compatibility can be extended to sets of interacting components, however, in the case of several requester components interacting with one or more provider components, as is typically the case of cleint-server applications, the requests from different components can be interleaved and then verifying component compatibility must take into account all possible interleavings of requests. Such interleaving of requests can lead to unexpected behavior of the composed system, e.g. a deadlock can occur. Service renaming is proposed as a method of systematic eliminating of such unexpected effects and streamlining component compositions

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

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

Computational fluid dynamics analysis of multi-element, high-lift aerofoil sections at transonic manoeuvre conditions

The application of a previously-developed computational method to the prediction of high-lift performance for multi-element aerofoil sections operating at transonic flow conditions is described. The flows are computed by solving the Reynolds-averaged Navier-Stokes equations, using a full differential Reynolds-stress turbulence model to evaluate the various Reynolds-stress components appearing in the governing mean-flow equations. Algebraic wall functions are used to bridge the molecular-viscosity dominated region immediately adjacent to the aerofoil surfaces. An unstructured-grid based Computational Fluid Dynamics methodology is used to deal with the geometric complexity of the multi-element aerofoil configurations. Initial results are presented for the viscous, transonic flow development around the SKF 1.1 supercritical aerofoil section, equipped with either a trailing-edge flap or a leading-edge slat. Predicted surface pressure distributions generally compare well with experimental data for the two high-lift aerofoil geometries considered, at a free-stream Mach number of 0.6 and over a range of incidence angles. There are some discrepancies in the regions immediately downstream of shock wave/boundary layer interactions, possibly resulting from the use of wall-function boundary conditions in the computations. Predicted Mach number contours indicate the complexity of the transonic flow fields for high-lift configurations, with the slat wake passing through an extensive supersonic-flow region, terminated by a normal shock wave, on the main aerofoil upper surface, for exampl