Corrosion of bronzes by extended wetting with single versus mixed acidic pollutants

The corrosion of bronzes was examined in the context of single-acid versus mixed-acid (as in urban acid rain) solutions. Two bi-component bronzes (copper with either 3% Sn or 7% Sn) that closely represent those of historic artifacts were immersed for five weeks in conditions designed to replicate those experienced by statues and ornaments in cities where rainfall and humidity constantly produce an electrolyte layer on the surfaces of bronzes. Ions, acids, and particles of pollutants can dissolve in this layer, resulting in a variety of harsh corrosion processes. The kinetics of corrosion and the properties of the resulting patinas were monitored weekly by electrochemical impedance spectroscopy and open-circuit potential measurements. The sizes and appearances of the corrosion products were monitored and used to estimate the progress of the corrosion, whose crystalline structures were visualized using scanning electron microscopy with energy dispersive spectroscopy, identified by X-ray diffraction, and characterized by spectrocolorimetry. The electrochemical measurements demonstrated that greater damage (in terms of color change and corrosion product formation) did not correspond to deficiencies in protection. The mixed-acid solution did not corrode the bronzes, as would be expected from the additive effects of the single acids. The postulated mechanisms of metal dissolution appear to be specific to a particular bronze alloy, with the tin component playing an important role

First results on the use of a EDXRF scanner for 3D imaging of paintings

A 3D map of chemical elements distribution from energy-dispersive X-ray fluorescence (EDXRF) analysis would be a perfect conclusion in a detailed study of any type of artifact. This map can be easily achieved by using synchrotron light as source of radiation, and microoptics both at the source and at the detector. In such a manner a micro-voxel is irradiated and detected, which can be at any depth with respect to the surface of the artifact. This method is effective but needs a high-intensity X-ray source; therefore, its use in archaeometry is limited. An alternative method is proposed in the present paper, which uses a portable EDXRF-device to measure the altered Kα/Kβ or Lα/Lβ-ratios, which allow to locate the chemical elements. Several examples are described

Rest tremor in Parkinson's disease: body distribution and time of appearance

Objective To assess body distribution and timing of appearance of rest tremor in Parkinson's disease. Methods Information was obtained by a computerized database containing historical information collected at the first visit and data collected during the subsequent follow-up visits. Information on rest tremor developed during the follow-up could be therefore obtained by our own observation in a proportion of patients. Results Among 289 patients, rest tremor was reported at disease onset in 65.4% of cases and detected at last follow-up examination in 74.4% of patients. Analysis of patients who did not report rest tremor at disease onset indicated that 26% of such patients (9% in the overall population) manifested rest tremor over the disease course. Rest tremor spread to new sites in 39% of patients who manifested rest tremor at disease onset. Regardless of tremor presentation at disease onset or during the follow-up, upper limb was the most frequent tremor localization. Over the follow-up, rest tremor developed faster in the upper limb than in other body sites. The risk of developing rest tremor during the follow-up was not affected by sex, side of motor symptom onset and site of tremor presentation. However, age of disease onset > 63 years was associated with an increased risk of rest tremor spread. Conclusions This study provides new information about body distribution and timing of rest tremor appearance during the course of early stages of Parkinson's disease that may help clinicians in patients' counselling

XISMuS x-ray fluorescence imaging software for multiple samples

X-rays have long been used as a non-destructive analytical technique to investigate artefacts and objects that can be considered cultural heritage. With the unceasing development of technologies and miniaturization of electronics, X-ray Fluorescence (XRF) analysis has undergone a natural evolution, being now extensively used in a bi-dimensional manner, scanning whole surfaces and generating astonishing amounts of data. Evaluating all this data demands a software distribution or at least a stand-alone algorithm. The former being an obvious choice, as software are easy to install and the learning curve is fast. Moreover, developing a proprietary algorithm is time consuming and not always needed for the average user. In this scope, XIMuS was developed as an ad hoc software for macro-XRF analysis (MA-XRF), with an intuitive and simple graphical user interface (GUI). The software provides several built-in tools, staple for the interpretation of X-ray fluorescence data, automated data evaluation and some novelty functionalities as data stitching. XISMuS creates an iterative user database as samples are loaded and compiled through usage, facilitating navigation through different datasets. Simultaneous samples can be loaded in separate instances for comparison purposes. Elemental mapping is made simple, the methods available are described and have each one an application for fast, balanced or precise calculations, supporting parallel computing. Ratios between elements in specific regions of the image can be measured while a region-derived spectrum is shown and updated live. Image correlation can be performed supporting the usage of threshold filters and/or region selection. Batch exporting is also available, cross-normalizing the input datasets

Behind the Image, Beyond the Image

The volume includes papers presented at the III International Conference of PhD students of the Department of Philosophy and Cultural Heritage of Ca’ Foscari University of Venice and the State Institute for Art Studies of Moscow (Venice, 22-24 September 2021). The word ‘image’ derives from the Latin imago, a word that has many different meanings that go from ‘portrait’ to ‘ghost’, from ‘idea’ to ‘dream’, from ‘memory’ to ‘reflection’. We most commonly associate the word ‘image’ with a picture, but its etymology keeps reminding us of its infinite conceptual potential. In his famous book Behind the Image: The Art of Reading Paintings, Federico Zeri argues that there are infinite ways to observe the work of art as an image. But since the image is something that goes beyond its mere material and physical form and refers to the categories of perception and thought, the expression “beyond the image” encourages new formulations related to this polyvalent concept. The image, the imagination and the imaginable are the transversal categories that the papers collected in this volume aim to explore, inquiring the concept of image as a metaphor, a model, a method, a representation, a tool for a new understanding of reality

Gold and Silver joining technologies in the Moche Tombs “Señor de Sipán” and “Señora de Cao jewelery

About 200 gold and silver funerary ornaments from the Moche tombs “Señor de Sipán” and “Señora de Cao” were analyzed to determine their metallurgic characteristics. Of particular interest was the question about the gold-silver joining process. To this aim, following methods were employed, all based on the use of X-rays: - energy dispersive X-ray fluorescence; - transmission of monoenergetic fluorescent X-rays; - radiography. At least three joining methods were possibly identified: - of gluing gold and silver sheets; - of brazing using a proper solder; - of using a mercury amalgam

Impact of Lactobacillus reuteri Supplementation on Anti-Helicobacter pylori Levofloxacin-Based Second-Line Therapy

Introduction. Helicobacter pylori eradication therapy has the potential burden of antibiotic-associated gastrointestinal (GI) side effects. The occurrence of side effects is among the major drawbacks of such regimens. GI manifestations may be related to alterations in the intestinal microflora. Probiotics can prevent or reduce antibiotic-associated side effects and have an inhibitory effect on H. pylori. Methods. To define the efficacy of Lactobacillus reuteri supplementation in H. pylori eradication and in preventing GI-associated side effects during a second-line levofloxacin triple therapy. 90 H. pylori-positive patients receive for 7 days a second-line triple therapy with esomeprazole, levofloxacin, and amoxicillin with L. reuteri for 14 days (group 1) and without probiotic supplementation (group 2). Each subject received a validated questionnaire to record symptoms everyday for 4 weeks from the start of therapy. H. pylori status and side effects were assessed 6 weeks after treatment. Results. The eradication rate was significantly influenced by probiotic supplementation with L. reuteri (group 1: 36/45, 80%; group 2: 28/45 62%; P < 0.05). The incidence of nausea and diarrhoea in group 1 was significantly lower than that in group 2. Conclusion. In H. pylori-positive subjects L. reuteri supplementation increases the eradication rate while reducing the incidence of the most common side effects associated with antibiotic therapy in second-line treatment

Survey archaeology and regional analysis. A conceptual model on the selection of past dynamics during the Holocene in Wadi Abiod, Aures, Eastern Algeria

This paper inserted within a geoarchaeological study, provides a model for the investigation and the support of past dynamics of a mountainous landscape in the Aures region (Algeria) during the Holocene. It introduces the first analysis based on the detailed mapping of morphological features of the study area in relation with a typomorphology theoretical model that was confronted with data from archaeological research. Our results suggest that the choice of the prehistorical movement processes has been driven by the outcrop of some deposits and the presence of specific landforms, such as high and low-relief areas. This approach was applied to a sector with controversial archaeological evidences (the valley of Wadi Abiod), where geological and morphological analyses support archaeological research in the reconstruction of the ancient pathways during the Holocene. This integrated approach can help archaeologists to understand and then discover ancient courses crossing complex in impervious landscapes such as the intramountain Lands

Testing the accuracy of the calculation of gold leaf thickness by MC simulations and MA-XRF scanning

The use of X-ray fluorescence (XRF) scanning systems has become a common practice in many application sectors. In multistratified and heterogeneous samples, the simple analysis of an XRF spectrum as a response of the entire sample is not reliable, so different spectral analysis techniques have been proposed to detect the presence of surface stratification. One commonly studied case is that of gilding, i.e., the presence of a superimposing gold-leaf layer. The observation of changes in the net peak ratios of a single element or of several elements in an XRF spectrum is a well-developed practice, but is still not used in the case of XRF scanning (macro-X-Ray fluorescence scanning, MA-XRF), a technique that can be described as the extrapolation of XRF spot analysis to a second dimension, scanning a sample surface instead. This practice can yield information on the overlaying layer thickness, if some properties of the sample are known—or estimated—beforehand, e.g., the overlapping layer’s chemical composition and the matrix effect contribution from the bulk material (thick ratio). This work proposes the use of an algorithm to calculate the thickness distribution of a superimposing gold layer accurately and automatically through the differential attenuation method by using MA-XRF datasets in a total noninvasive manner. This approach has the clear advantage over the traditional spot sampling of allowing the generation of a surface heightmap to better visualize and interpret the data, as well as a considerably larger sample space. Monte Carlo simulations were used to verify the influence of the medium used to adhere the gold leaves to the substrate and to generate known spectra to assess the algorithm’s accuracy

On the Use of Biobased Waxes to Tune Thermal and Mechanical Properties of Polyhydroxyalkanoates–Bran Biocomposites

In this work, processability and mechanical performances of bio-composites based on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) containing 5, 10, and 15 wt % of bran fibers, untreated and treated with natural carnauba and bee waxes were evaluated. Wheat bran, the main byproduct of flour milling, was used as filler to reduce the final cost of the PHBV-based composites and, in the same time, to find a potential valorization to this agro-food by-product, widely available at low cost. The results showed that the wheat bran powder did not act as reinforcement, but as filler for PHBV, due to an unfavorable aspect ratio of the particles and poor adhesion with the polymeric matrix, with consequent moderate loss in mechanical properties (tensile strength and elongation at break). The surface treatment of the wheat bran particles with waxes, and in particular with beeswax, was found to improve the mechanical performance in terms of tensile properties and impact resistance of the composites, enhancing the adhesion between the PHBV-based polymeric matrix and the bran fibers, as confirmed by predictive analytic models and dynamic mechanical analysis results