30 research outputs found
The importance of tomography studying wooden artefacts: A comparison with radiography in the case of a coffin lid from ancient Egypt
Aiding the conservation of two wooden Buddhist sculptures with 3D imaging and spectroscopic techniques
The conservation of Buddhist sculptures that were transferred to Europe at some point during their lifetime raises numerous questions: while these objects historically served a religious, devotional purpose, many of them currently belong to museums or private collections, where they are detached from their original context and often adapted to western taste.
A scientific study was carried out to address questions from Museo d'Arte Orientale of Turin curators in terms of whether these artifacts might be forgeries or replicas, and how they may have transformed over time. Several analytical techniques were used for materials identification and to study the production technique, ultimately aiming to discriminate the original materials from those added within later interventions
X-ray Imaging Investigation on the Gilding Technique of an Ancient Egyptian Taweret Wooden Statuette
Diagnostic physical methods are increasingly applied to Cultural Heritage both for scientific investigations and conservation purposes. In particular, the X-ray imaging techniques of computed tomography (CT) and digital radiography (DR) are non-destructive investigation methods to study an object, being able to give information on its inner structure. In this paper, we present the results of the X-ray imaging study on an ancient Egyptian statuette (Late Period 722–30 BCE) belonging to the collection of Museo Egizio in Torino and representing an Egyptian goddess called Taweret, carved on wood and gilded with some colored details. Since few specific studies have been focused on materials and techniques used in Ancient Egypt for gilding, a detailed investigation was started in order to verify the technical features of the decoration in this sculpture. Specifically, DR and CT analyses have been performed at the Centro Conservazione e Restauro “La Venaria Reale” (CCR), with a new high resolution flat-panel detector, that allowed us to perform tomographic analysis reaching a final resolution better than the one achievable with the previous apparatus operating in the CCR
An Ancient Egyptian Multilayered Polychrome Wooden Sculpture Belonging to the Museo Egizio of Torino: Characterization of Painting Materials and Design of Cleaning Processes by Means of Highly Retentive Hydrogels
This contribution focuses on the conservation of an Egyptian wooden sculpture (Inventory Number Cat. 745) belonging to the Museo Egizio of Torino in northwest Italy. A preliminary and interdisciplinary study of constituent painting materials and their layering is here provided. It was conducted by means of a multi-technique approach starting from non-invasive multispectral analysis on the whole object, and subsequently, on selected micro-samples. In particular, visible fluorescence induced by ultraviolet radiation (UVF), infrared reflectography (IRR) and visible--induced infrared luminescence were used on the whole object. The micro-samples were analysed by means of an optical microscope with visible and UV light sources, a scanning electron microscope (SEM) with an energy-dispersive X-ray spectrometer (EDX), Fourier transform infrared (FT-IR) spectrometer, pyrolysis-gas chromatography/mass spectrometer (Py-GC/MS) and micro-particle induced X-ray emission (PIXE). The characterization of the painting materials allowed the detection of Egyptian blue and Egyptian green, and also confirmed the pertinence of the top brown layer to the original materials, which is a key point to design a suitable surface treatment. In fact, due to the water sensitiveness of the original materials, only few options were available to perform cleaning operations on this artwork. To setup the cleaning procedure, we performed several preliminary tests on mockups using dry cleaning materials, commonly used to treat reactive surfaces, and innovative highly water retentive hydrogels, which can potentially limit the mechanical action on the original surface while proving excellent cleaning results. Overall, this study has proved fundamental to increase our knowledge on ancient Egyptian artistic techniques and contribute to hypothesize the possible provenance of the artefact. It also demonstrated that polyvinyl alcohol-based retentive gels allow for the safe and efficient cleaning of extremely water sensitive painted surfaces, as those typical of ancient Egyptian artefacts
Flexible composite films with enhanced piezoelectric properties for energy harvesting and wireless ultrasound-powered technology
In the last years, ultrasound energy harvesting has emerged as the most promising technique for wireless power supply of implanted medical devices. These devices require flexible piezoelectric materials with high piezoelectric response in the ultrasonic range. Here we report on bio-compatible NBT-BT/PVDF flexible composites, with variable filler content up to 50 vol%, prepared by a properly designed and optimized process, which incorporates in a complex connectivity pattern fully sintered NBT-BT crystalline powders in a PVDF matrix. The dielectric constant of the flexible composites increased from 10 of pure PVDF polymer to 110 of composite films with 50 vol% NBT-BT content, while the high frequency piezoelectric d33 constant increased from 0.2 pC/N to 33 pC/N for the same samples. The composite with 50 vol% NBT-BT exhibits the figure of merit for the harvested ultrasound energy d33g33 ≅ 1.54 × 10−12 m3/J, which is comparable to the figure of merit for the NBT-BT piezoelectric ceramic (1.8 × 10−12 m3/J) and higher than other reported results for random composites. Based on these results, this study provides an easy method to fabricate random flexible piezoelectric composites with enhanced high frequency piezoelectric response and high energy density harvested from an ultrasound source
Advantages and limitations of active phase silanization in PVDF composites: Focus on electrical properties and energy harvesting potential
In order to further improve the performance of 0.94[(Bi0.5Na0.5)TiO3]-0.06BaTiO3/
polyvinylidene fluoride (NBT-BT/PVDF) flexible composite films prepared by the
hot-pressing method, the effect of surface modification of the NBT-BT particles on
the structure and properties of the films was investigated. Two coupling agents,
namely, (3-aminopropyl)triethoxysilane (APTES) and dodecyl triethoxysilane
(DDTES) were added to enhance dispersion and interfacial adhesion of the active
phase powder with the polymer matrix. The highest amount of the electroactive
PVDF β-phase was formed in APTES-modified samples while in DDTES samples
mainly γ-phase was formed as shown by Fourier-transform infrared spectroscopy
analysis. Differential scanning calorimetry measurements indicated that the addition
of filler particles reduced the total crystallinity degree of the PVDF. Dielectric
permittivity values as well as dielectric losses decreased for silanized samples due
to reduced tension at the interface between particles and polymer. Strong intermolecular
interaction between the PVDF chains and the APTES-modified particles
led to enhanced breakdown strength of these samples. The highest level of
agglomeration in the DDTES-modified samples induced the deterioration of ferroelectric
properties. The highest voltage output of 15 V and 225 μW of powerwas
obtained for the APTES-modified harvester, evidencing their potential for energy
harvesting applications
ENHANCED PROPERTIES OF PVDF COMPOSITES BY ACTIVE PHASE SILANIZATION
0.94[(Bi0.5Na0.5)TiO3]-0.06BaTiO3/polyvinylidene fluoride flexible composite films were prepared by the hot-pressing method. Surface modification of active phase particles was performed using two coupling agents, namely, (3- aminopropyl)triethoxysilane (APTES) and dodecyl triethoxysilane (DDTES) to enable good adhesion of active phase particles with the polymer matrix. The highest amount of electroactive PVDF β- phase was formed in APTES-modified samples while in DDTES samples mainly γ- phase was formed. Dielectric permittivity values and dielectric losses decreased for silanized samples due to reduced tension at the interface between particles and polymer. Strong intermolecular interaction between the PVDF chains and the APTES-modified particles led to enhanced breakdown strength of these samples. After the polarization of films, energy harvesting potential was evaluated for all samples. The highest voltage output of ~ 15 V and power ~ 225 μW were obtained for a single APTES-modified harvester [1-2]
Immunity and vaccine development efforts against Trypanosoma cruzi
Artículo de revisión especializadoTrypanosoma cruzi (T. cruzi) is the causative agent for Chagas disease (CD). There is a critical lack of methods for prevention of infection or treatment of acute infection and chronic disease. Studies in experimental models have suggested that the protective immunity against T. cruzi infection requires the elicitation of Th1 cytokines, lytic antibodies and the concerted activities of macrophages, T helper cells, and cytotoxic T lymphocytes (CTLs). In this review, we summarize the research efforts in vaccine development to date and the challenges faced in achieving an efficient prophylactic or therapeutic vaccine against human CD.UTM