1,720,968 research outputs found
Diagnostica delle murature storiche con prove soniche: sperimentazione in laboratorio
No full textIl presente lavoro sperimentale di laboratorio è incentrato sulla valutazione dello stato di integrità o ammaloramento di strutture storiche (identificazione della presenza di inclusioni, crepe, fessure, vuoti, difetti, degrado, ecc.) mediante tecniche non distruttive quali analisi soniche in trasmissione diretta ed indiretta, applicate a provini in muratura in scala reale appositamente costruiti. Inoltre, lo studio fornisce un trattamento dei dati di immediata comprensione, grazie alla loro visualizzazione attraverso grafici e mappe, impiegando software di rapido e facile utilizzo, al fine di comunicare gli esiti delle prove anche ad utenti non specialisti delle tecniche applicate
Herodian Machaerus Fortress (Jordan): Investigation of Mortars Belonging to the Hydraulic Constructions
No full textMachaerus Fortress, overlooking on a hilltop the Transjordan side of the Dead Sea, represents an important example of the Herodian defence structures. It was a model of engineering, considering both its military function and the offered quality-of-life. In fact, this site hosted hydraulic constructions with an estimated capacity of the reservoirs of 3000 m(3) (3.000.000 l) per year, allowing people to have supply of potable water and for all the human activities. Given the unquestionable significance of this archaeological site, a comprehensive characterization of the mortars utilized, especially in the hydraulic structures, is here discussed. Therefore, the present work provides hints for new insights on the construction techniques utilized in this area, interesting both from the historical and from the engineering point of view. Moreover, the results here illustrated constitute a valid support in the decision making of compatible materials to be employed in future restoration works
Characterization of the Stone Masonries and Evaluation of the Environmental Impact in Panamá Viejo: A Contribution for the Conservation of the Monumental Complex
No full textA fundamental step in the best preservation of heritage materials is investigating their chemical and physical characteristics, and understanding how they interact with the surrounding environment. For this reason, the stone masonry of the monumental UNESCO site of Panamá Viejo was subjected to a thorough study to characterize the materials and evaluate their state of conservation. Additionally, potential outcrops were explored in order to identify sites for the supply of raw materials. The methodological approach encompassed mineralogical-petrographic investigations using stereomicroscopy, polarized light microscopy (PLM), X-ray powder diffraction (XRPD), scanning electron microscopy and energy dispersive X-ray spectrometry (ESEM-EDS) and X-ray fluorescence (XRF). The results revealed that the masonries primarily consists of polygenic breccia, basaltic andesite, rhyodacite, tuffite, and rhyolite. In addition, at the potential quarries, breccia and basaltic andesite were identified. The porous structure was studied using mercury intrusion porosimetry (MIP). Possible issues due to salt dissolution/crystallization cycles were considered. Consequently, ion chromatography (IC) was conducted on samples exhibiting alteration patinas to study the presence of soluble salts. In assessing the state of conservation, prevalent forms of deterioration included biological colonization, detachments, material loss, potential salt weathering, and chromatic alteration. In conclusion, the outcomes of this work provide a valuable resource for the current and future preservation of this site
A multi-analytical approach to study the chemical composition of total suspended particulate matter (TSP) to assess the impact on urban monumental heritage in Florence
Full text linkIn the present paper total suspended particulate matter (TSP) was collected at the S. Marco Museum in Florence during seasonal monitoring campaigns carried out in 2013 and 2014. The analyses focused on the determination of TSP chemical composition: main ions, organic carbon (OC), elemental carbon (EC), water soluble organic compounds (WSOC) and levoglucosa which is considered the specific marker for wood burning. The analysis of TSP composition in Florence historical centre is of interest to assess what the damage caused to the surfaces of the urban monumental heritage could be. TSP higher value has been registered during December 2013 (58,6 μg/m3 ± 7,3 μg/m3) while the lower value has been registered in July 2013 (28,5 μg/m3 ± 2,2 μg/m3). OC and EC were also higher in winter with respect to summer. Sulphate is characterized by quite constant values during all the examined periods while ammonium and nitrate were higher in winter. The seasonal contribution of different sources such as combustion processes (from traffic and wood burning) and soil dust resuspension has been evidenced. In particular during winter a high concentration of levoglucosan, the specific marker for wood combustion, has been determined. Finally, all the data obtained were correlated with those previously determined in another study carried out in 2003 at the Baptistery of San Giovanni in Florence in order to evaluate any possible change in the atmospheric pollution composition
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Growth of Silver Nanoparticles Embedded in a Polyacrylamide—Alginate Hybrid Hydrogel
No full textHydrogels represent a versatile class of materials with remarkable potential as
three-dimensional matrices for nanoparticle integration. This study explores the mechanism of silver nanoparticle formation within a polyacrylamide–alginate hybrid hydrogel,
employing a controlled reduction–oxidation reaction between silver nitrate (AgNO3) and
sodium borohydride (NaBH4) across a temperature gradient (5–70 ◦C). Characterization
techniques, including Raman, infrared, and UV-Vis spectroscopies, X-ray diffraction, and
scanning electron microscopy, were employed to analyze the structural and optical properties of the nanoparticles and the hydrogel. The results show that, as the temperature rose,
nanoparticle numbers decreased, while their size increased. Consistently octahedral in
shape and averaging 100–120 nm, these nanoparticles revealed a temperature-dependent
growth pattern, with rare larger crystals emerging more frequently at higher temperatures. The findings highlight the potential of hybrid hydrogels as effective matrices for
the incorporation of metal nanoparticles, paving the way for applications in drug delivery,
biosensing, and antimicrobial treatments
Compatibility of niobium, vanadium and P22 steel in high temperature flowing LiPb
No full textThe LiPb loops of the WCLL BB (Water Cooled Lithium-Lead Breeding Blanket) have the primary aim of routing tritium-rich LiPb from the Breeding Blanket to the Tritium Extraction System of DEMO Reactor. Besides, the loops maintain LiPb in the desired conditions and purify it from corrosion and activated products and from helium generated by the neutron transmutation of lithium. For some of these tasks the loops need special functional materials. Among them, niobium and vanadium are widely considered for the tritium extraction technologies for their high permeability to tritium. In addition, the loops will be made of structural materials capable of withstanding the operative conditions and the aggressive environment. The current reference material for the piping is the ASTM A335 Grade P22. This paper investigates the compatibility at 500 °C of niobium, vanadium and P22 with LiPb flowing at 0.5 m/s. This velocity is the maximum foreseen in the LiPb loops, while the temperature was chosen following a conservative approach, as the maximum expected temperature is 450 °C in the BB and 330 °C in the LiPb loops. The specimens of the three materials were exposed for 1,000, 2,000 and 4,000 h in IELLLO LiPb facility at ENEA Brasimone Research centre. After the exposure, the specimens were examined by SEM-EDX, both in cross-section and surface view, XRD analyses were performed in order to investigate potential corrosion compounds formed. Weight loss analyses were also performed on niobium specimens, after chemical cleaning from adherent LiPb. The analyses highlighted the impact of corrosion products and their interaction with refractory metals (Ni and Fe) and P22 steel (Cr, after redeposition)
Preliminary Characterization of Alumina-Forming Austenitic–Type Advanced Alloys as Structural Materials for LFRs
No full textThe lead-cooled fast reactor (LFR) is one of the most promising Generation-IV nuclear designs currently under development in Europe, China, and the United States. LFRs can ensure enhanced performance and minimal waste production thanks to a closed fuel cycle, but they also have some issues that need to be addressed. One of the most critical is the long-term degradation process initiated in structural materials exposed to liquid Pb. The present state of the art has shown that commercial austenitic steels, such as American Iron and Steel Institute 316L and 15-15Ti can be adopted as structural materials in Pb environments up to 480°C, beyond which they start to experience the dissolution of constituting alloying elements (Ni, Cr, and Fe) if not protected by a coating or by surface modification. In more recent years, a lot of research effort has been done in order to develop new coating technologies and new base materials for operation with liquid Pb at higher temperatures. Among the newest alloys, alumina-forming austenitic (AFA) steels have gained interest in the research community because of their promising corrosion resistance results even at temperatures of 600°C. In this framework, an experimental campaign has been run at the Research Center ENEA of Brasimone that aims to characterize the behavior of two different AFA steels (with low and high Ni content in their composition) in static Pb at 650°C and 750°C with a moderate low oxygen concentration (10−6 wt %). After exposure, the AFA steels were characterized from the point of view of the morphology and composition, and the results are presented and discussed here
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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