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

Aligning MIS5 proxy records from Lake Ohrid (FYROM) with independently dated Mediterranean archives: implications for core chronology

The DEEP site sediment sequence obtained during the ICDP SCOPSCO project at Lake Ohrid was dated using tephrostratigraphic information, cyclostratigraphy, and orbital tuning through marine isotope record. Although this approach is suitable for the generation of a general chronological framework of the long succession, it is insufficient to resolve more detailed paleoclimatological questions, such as leads and lags of climate events between marine and terrestrial records or between different regions. In this paper, we demonstrate how the use of different tie points can affect cyclostratigraphy and orbital tuning for the period between ca. 140 and 70 ka and how the results can be correlated with directly/indirectly radiometrically-dated Mediterranean marine and continental proxy records. The alternative age model obtained shows consistent differences with that proposed by Francke et al. (2015) for the same interval, in particular at the level of the MIS6-5e transition. According to this age model, different proxies from the DEEP site sediment record support an increase of temperatures between glacial to interglacial conditions, which is almost synchronous with a rapid increase in sea surface temperature observed in the western Mediterranean. The results show how important a detailed study of independent chronological tie points is for synchronizing different records and to highlight asynchronisms of climate events

Central Mediterranean tephrochronology between 313 and 366 ka. New insights from the Fucino paleolake sediment succession

Thirty-two tephra layers were identified in the time-interval 313–366 ka (Marine Isotope Stages 9–10) of the Quaternary lacustrine succession of the Fucino Basin, central Italy. Twenty-seven of these tephra layers yielded suitable geochemical material to explore their volcanic origins. Investigations also included the acquisition of geochemical data of some relevant, chronologically compatible proximal units from Italian volcanoes. The record contains tephra from some well known eruptions and eruptive sequences of Roman and Roccamonfina volcanoes, such as the Magliano Romano Plinian Fall, the Orvieto–Bagnoregio Ignimbrite, the Lower White Trachytic Tuff and the Brown Leucitic Tuff. In addition, the record documents eruptions currently undescribed in proximal (i.e. near-vent) sections, suggesting a more complex history of the major eruptions of the Colli Albani, Sabatini, Vulsini and Roccamonfinavolcanoes between 313 and 366 ka. Six of the investigated tephra layers were directly dated by single-crystal-fusion 40Ar/39Ar dating, providing the basis for a Bayesian age–depth model and a reassessment of the chronologies for both already known and dated eruptive units and for so far undated eruptions. The results provide a significant contribution for improving knowledge on the peri-Tyrrhenian explosive activity as well as for extending the Mediterranean tephrostratigraphical framework, which was previously based on limited proximal and distal archives for that time interval

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

Impact of CaSO4-rich soil on Miocene surface preservation and Quaternary sinuous to meandering channel forms in the hyperarid Atacama Desert

The Atacama Desert is the driest and oldest desert on Earth. Despite the abundance evidence for long-term landscape stability, there are subtle signs of localised fluvial erosion and deposition since the onset of hyperaridity in the rock record. In the dry core of the Atacama Desert, pluvial episodes allowed antecedent drainage to incise into uplifting fault scarps, which in turn generated sinuous to meandering channels. Incision of ancient alluvial fan surfaces occurred during intermittent fluvial periods, albeit without signs of surface erosion. Fluvial incision during predominantly hyperarid climate periods is evident from these channels in unconsolidated alluvium. The absence of dense vegetation to provide bank stability and strength led us to investigate the potential role of regionally ubiquitous CaSO4-rich surface cover. This has enabled the preservation of Miocene surfaces and we hypothesize that it provided the required bank stability by adding strength to the upper decimetre to meter of incised alluvium to allow high sinuosity of stream channels to form during pluvial episodes in the Quaternary

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

The geodynamic and limnological evolution of Balkan Lake Ohrid, possibly the oldest extant lake in Europe

Studies of the upper 447 m of the DEEP site sediment succession from central Lake Ohrid, Balkan Peninsula, North Macedonia and Albania provided important insights into the regional climate history and evolutionary dynamics since permanent lacustrine conditions established at 1.36 million years ago (Ma). This paper focuses on the entire 584-m-long DEEP sediment succession and a comparison to a 197-m-long sediment succession from the Pestani site ~5 km to the east in the lake, where drilling ended close to the bedrock, to unravel the earliest history of Lake Ohrid and its basin development. 26Al/10Be dating of clasts from the base of the DEEP sediment succession implies that the sedimentation in the modern basin started at c. 2 Ma. Geophysical, sedimentological and micropalaeontological data allow for chronological information to be transposed from the DEEP to the Pestani succession. Fluvial conditions, slack water conditions, peat formation and/or complete desiccation prevailed at the DEEP and Pestani sites until 1.36 and 1.21 Ma, respectively, before a larger lake extended over both sites. Activation of karst aquifers to the east probably by tectonic activity and a potential existence of neighbouring Lake Prespa supported filling of Lake Ohrid. The lake deepened gradually, with a relatively constant vertical displacement rate of ~0.2 mm a−1 between the central and the eastern lateral basin and with greater water depth presumably during interglacial periods. Although the dynamic environment characterized by local processes and the fragmentary chronology of the basal sediment successions from both sites hamper palaeoclimatic significance prior to the existence of a larger lake, the new data provide an unprecedented and detailed picture of the geodynamic evolution of the basin and lake that is Europe’s presumed oldest extant freshwater lake