311 research outputs found
Deamidation at Asparagine and Glutamine As a Major Modification upon Deterioration/Aging of Proteinaceous Binders in MuralPaintings
Proteomic strategies are herein proved to be a
complementary approach to the well established amino acid
composition analysis for the characterization of the aging and
deterioration phenomena occurring to proteinaceous materials
in works-of-art. Amino acid analyses on several samples demonstrated
that proteins in the frescoes from the Camposanto
Monumentale in Pisa are deteriorated as revealed by the
decrease in Met, Lys, and Tyr content and by the presence in
all the samples of amino malonic acid as a result of Ser, Phe, and
Cys oxidation. Proteomic analysis identified deamidation at Asn
and Gln as a further major event occurred. This work paves the
way to the exploitation of proteomic strategies for the investigation
of the molecular effects of aging and deterioration in
historical objects. Results show that proteomic searches for
deamidation by liquid chromatography-tandem mass spectrometry
(LC-MS/MS) could constitute a routine analysis for paintings or any artistic and historic objects where proteins are present.
Peptides that can be used as molecular markers when casein is present were identified
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Steric sea level changes from ocean reanalyses at global and regional scales
Sea level has risen significantly in the recent decades and is expected to rise further based on recent climate projections. Ocean reanalyses that synthetize information from observing networks, dynamical ocean general circulation models, and atmospheric forcing data offer an attractive way to evaluate sea level trend and variability and partition the causes of such sea level changes at both global and regional scales. Here, we review recent utilization of reanalyses for steric sea level trend investigations. State-of-the-science ocean reanalysis products are then used to further infer steric sea level changes. In particular, we used an ensemble of centennial reanalyses at moderate spatial resolution (between 0.5 × 0.5 and 1 × 1 degree) and an ensemble of eddy-permitting reanalyses to quantify the trends and their uncertainty over the last century and the last two decades, respectively. All the datasets showed good performance in reproducing sea level changes. Centennial reanalyses reveal a 1900–2010 trend of steric sea level equal to 0.47 ± 0.04 mm year−1, in agreement with previous studies, with unprecedented rise since the mid-1990s. During the altimetry era, the latest vintage of reanalyses is shown to outperform the previous ones in terms of skill scores against the independent satellite data. They consistently reproduce global and regional upper ocean steric expansion and the association with climate variability, such as ENSO. However, the mass contribution to the global mean sea level rise is varying with products and its representability needs to be improved, as well as the contribution of deep and abyssal waters to the steric sea level rise. Similarly, high-resolution regional reanalyses for the European seas provide valuable information on sea level trends, their patterns, and their causes
sensitivity of the mediterranean sea level to atmospheric pressure and free surface elevation numerical formulation in nemo
Abstract. The sensitivity of the dynamics of the Mediterranean Sea to atmospheric pressure and free surface elevation formulation using NEMO (Nucleus for European Modelling of the Ocean) was evaluated. Four different experiments were carried out in the Mediterranean Sea using filtered or explicit free surface numerical schemes and accounting for the effect of atmospheric pressure in addition to wind and buoyancy fluxes. Model results were evaluated by coherency and power spectrum analysis with tide gauge data. We found that atmospheric pressure plays an important role for periods shorter than 100 days. The free surface formulation is important to obtain the correct ocean response for periods shorter than 30 days. At frequencies higher than 15 days−1 the Mediterranean basin's response to atmospheric pressure was not coherent and the performance of the model strongly depended on the specific area considered. A large-amplitude seasonal oscillation observed in the experiments using a filtered free surface was not evident in the corresponding explicit free surface formulation case, which was due to a phase shift between mass fluxes in the Gibraltar Strait and at the surface. The configuration with time splitting and atmospheric pressure always performed best; the differences were enhanced at very high frequencies
THE CAPO ROSSELLO BORE-HOLE (AGRIGENTO, SICILY) CYCLOSTRATIGRAPHIC AND PALEOCEANOGRAPHIC RECONSTRUCTIONS FROM QUANTITATIVE ANALYSES OF THE ZANCLEAN FORAMINIFERAL ASSEMBLAGES
Cyclostratigraphy based on the quantitative analyses of planktonic foraminifera in the Zanclean segment (M Pl 1 base of M Pl 3 biozones) of the bore-hole drilled in the Capo Rossello area (Sicily, Southern Italy) allows us to recognize that the calcareous plankton biostratigraphic events occur in the same cycles as identified by previous authors. Exceptional thick cycles which are thought to represent two precession cycles show two fluctuations is greater than the number of lithologic cycles. Between the base of the Pliocene and the first occurrence of Globorotalia puncticulata thirty-five lithologic cycles and thirty eight planktonic foraminifera fluctuations are present. By comparison with relative abundance fluctuations in the benthic foraminifera and the astronomical record is recognized. In particular, the BN>125 µm and the Planulina ariminensis quantitative distributions are related to the long eccentricity. Conversely, the relative abundance fluctuations of Siphonina reticulata, Cibicidoides bradyi, Pullenia bulloides and Uvigerina pygmaea appear to be generally forced by the precession periodicity, but in the intervals coincident with the eccentricity minima such a relationship is less clear. The very abundant and widespread distribution in several Mediterranean sites of S. reticulata, which we consider a quasi-endemic species of this basin during the Early and Middle Pliocene is anticovariant with the quantitative distribution of Cibicidoides brady-robertsonianus, which is considered a characteristic species of the North Atlantic Deep Water (NADW). This relationship suggest that a peculiar, intermediate water mass was present in the Mediterranean during this time interval. We propose for this water mass the name of Early Pliocene Mediterranenan Intermediate Water (EPMIW). According to bibliographic data that report the sharp decrease in abundance of S. reticulata during the M Pl 5 biozone, EPMIW was present in the Mediterranean basin until about 2.5 Ma. 
THE CAPO ROSSELLO BORE-HOLE (AGRIGENTO, SICILY) CYCLOSTRATIGRAPHIC AND PALEOCEANOGRAPHIC RECONSTRUCTIONS FROM QUANTITATIVE ANALYSES OF THE ZANCLEAN FORAMINIFERAL ASSEMBLAGES
Cyclostratigraphy based on the quantitative analyses of planktonic foraminifera in the Zanclean segment (M Pl 1 base of M Pl 3 biozones) of the bore-hole drilled in the Capo Rossello area (Sicily, Southern Italy) allows us to recognize that the calcareous plankton biostratigraphic events occur in the same cycles as identified by previous authors. Exceptional thick cycles which are thought to represent two precession cycles show two fluctuations is greater than the number of lithologic cycles. Between the base of the Pliocene and the first occurrence of Globorotalia puncticulata thirty-five lithologic cycles and thirty eight planktonic foraminifera fluctuations are present. By comparison with relative abundance fluctuations in the benthic foraminifera and the astronomical record is recognized. In particular, the BN>125 µm and the Planulina ariminensis quantitative distributions are related to the long eccentricity. Conversely, the relative abundance fluctuations of Siphonina reticulata, Cibicidoides bradyi, Pullenia bulloides and Uvigerina pygmaea appear to be generally forced by the precession periodicity, but in the intervals coincident with the eccentricity minima such a relationship is less clear. The very abundant and widespread distribution in several Mediterranean sites of S. reticulata, which we consider a quasi-endemic species of this basin during the Early and Middle Pliocene is anticovariant with the quantitative distribution of Cibicidoides brady-robertsonianus, which is considered a characteristic species of the North Atlantic Deep Water (NADW). This relationship suggest that a peculiar, intermediate water mass was present in the Mediterranean during this time interval. We propose for this water mass the name of Early Pliocene Mediterranenan Intermediate Water (EPMIW). According to bibliographic data that report the sharp decrease in abundance of S. reticulata during the M Pl 5 biozone, EPMIW was present in the Mediterranean basin until about 2.5 Ma. 
Sensitivity of the Mediterranean sea level to atmospheric pressure and free surface elevation numerical formulation in NEMO
The sensitivity of the dynamics of the Mediterranean Sea to atmospheric
pressure and free surface elevation formulation using NEMO (Nucleus for
European Modelling of the Ocean) was evaluated. Four different experiments
were carried out in the Mediterranean Sea using filtered or explicit free
surface numerical schemes and accounting for the effect of atmospheric
pressure in addition to wind and buoyancy fluxes. Model results were
evaluated by coherency and power spectrum analysis with tide gauge data. We
found that atmospheric pressure plays an important role for periods shorter
than 100 days. The free surface formulation is important to obtain the
correct ocean response for periods shorter than 30 days. At frequencies
higher than 15 days−1 the Mediterranean basin's response to atmospheric
pressure was not coherent and the performance of the model strongly depended
on the specific area considered. A large-amplitude seasonal oscillation
observed in the experiments using a filtered free surface was not evident in
the corresponding explicit free surface formulation case, which was due to a
phase shift between mass fluxes in the Gibraltar Strait and at the surface.
The configuration with time splitting and atmospheric pressure always
performed best; the differences were enhanced at very high frequencies
Contribution of future wide-swath altimetry missions to ocean analysis and forecasting
The impact of forthcoming wide-swath altimetry missions on the ocean analysis
and forecasting system was investigated by means of OSSEs (observing system
simulation experiments). These experiments were performed with a regional data assimilation system,
implemented in the Iberian–Biscay–Ireland (IBI) region, at 1∕12°
resolution using simulated observations derived from a fully eddy-resolving
free simulation at 1∕36° resolution over the same region. The
objective of the experiments was to assess the ability of different satellite
constellations to constrain the ocean analyses and forecasts, considering
both along-track altimeters and future wide-swath missions; consequently,
the capability of the data assimilation techniques used in the Mercator Ocean
operational system to effectively combine the different kinds of
measurements was also investigated. These assessments were carried out as part of a European Space Agency (ESA)
study on the potential role of wide-swath altimetry in future versions of the
European Union Copernicus programme. The impact of future wide-swath
altimetry data is evident for investigating the reliability of sea level values in
OSSEs. The most significant results were obtained when looking at the sensitivity
of the system to wide-swath instrumental error: considering a constellation
of three nadir and two accurate (small instrumental error) wide-swath
altimeters, the error in ocean analysis was reduced by up to 50 %
compared to conventional altimeters. Investigating the impact of the
repetitivity of the future measurements, the results showed that two
wide-swath missions had a major impact on sea-level forecasting – increasing
the accuracy over the entire time window of the 5-day forecasts – compared
with a single wide-swath instrument. A spectral analysis underlined that the
contributions of wide-swath altimetry data observed in ocean analyses and
forecast statistics were mainly due to the more accurate resolution,
compared with along-track data, of ocean variability at spatial scales
smaller than 100 km. Considering the ocean currents, the results confirmed
that the information provided by wide-swath measurements at the surface is
propagated down the water column and has a considerable impact (30 %) on
ocean currents (up to a depth of 300 m), compared with the present
constellation of altimeters. The ocean analysis and forecasting systems used
here are those currently used by the Copernicus Marine Environment and
Monitoring Service (CMEMS) to provide operational services and ocean
reanalysis. The results obtained in the OSSEs considering along-track
altimeters were consistent with those derived from real data (observing
system experiments, OSEs). OSSEs can also be used to assess the potential of
new observing systems, and in this study the results showed that future
constellations of altimeters will have a major impact on constraining the
CMEMS ocean analysis and forecasting systems and their applications.</p
A simple and reliable methodology to detect egg white in art samples
A protocol for a simple and reliable dot-blot immunoassay was developed and optimized to test work of art samples
for the presence of specific proteinaceus material (i.e. ovalbumin-based). The analytical protocol has been extensively
set up with respect, among the other, to protein extraction conditions, to densitometric analysis and to the colorimetric
reaction conditions. Feasibility evaluation demonstrated that a commercial scanner and a free image analysis software
can be used for the data acquisition and elaboration, thus facilitating the application of the proposed protocol to
commonly equipped laboratories and to laboratories of museums and conservation centres. The introduction of
method of standard additions in the analysis of fresh and artificially aged laboratory-prepared samples, containing
egg white and various pigments, allowed us to evaluate the matrix effect and the effect of sample aging and to generate
threshold density values useful for the detection of ovalbumin in samples from ancient works of art. The efficacy of
the developed dot-blot immunoassay was proved testing microsamples from 13th–16th century mural paintings of
Saint Francesco Church in Lodi (Italy). Despite the aging, the altered conditions of conservation, the complex matrix,
and the micro-size of samples, the presence of ovalbumin was detected in all those mural painting samples where
mass-spectrometry-based proteomic analysis unambiguously detected ovalbumin peptides
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