1,721,036 research outputs found
Ossalati e biodegrado.
No full textL’origine del materiale organico normalmente incontrato sulla superficie di monumenti ed edifici storici e archeologici in marmo e calcare è di complessa individuazione.
Diversi possono essere infatti i fattori che contribuiscono alla sua presenza: prodotti di degrado biologico, alterazione di trattamenti protettivi applicati in passato e deposizione atmosferica. Tra i composti organici, anioni a corta catena carboniosa quali acetati, formiati ed ossalati, vengono costantemente identificati unitamente agli anioni traccianti tipici di inquinamento atmosferico, in concentrazioni non trascurabili, mediante analisi in cromatografia ionica, nelle croste nere campionate su monumenti ed edifici situati in aree urbane o industrializzate. Whewellite e weddellite, ossalati di calcio monoidrato e biidrato rispettivamente, sono stati frequentemente riscontrati, attraverso analisi in microscopia ottica polarizzata su sezioni sottili, microscopia elettronica a scansione e diffrattometria a raggi x, sotto forma di sottili strati superficiali su monumenti ed oggetti in marmo e calcare localizzati in diverse aree geografiche ed appartenenti a vari periodi storici.
In questo lavoro sono sintetizzate le ipotesi di lavoro sviluppate e i sultati ottenuti mediante l’applicazione di nuove metodologie analitiche al fine di colmare le lacune attualmente esistenti in letteratura riguardo questa problematica di grande rilevanza per la ricerca applicata ai beni culturali
Atmospheric pollution effects on hydraulic mortars.
No full textOn the subject of ancient hydraulic mortars, very few studies are reported in the literature regarding the origin, composition and identification of the various degradation typologies. Therefore, little is known on the effects of atmospheric pollutants, particularly those due to the dry and wet deposition of sulphur and carbon compounds, on the hydraulic mortars used in historic monuments, and few quantitative data are available. In fact, water from rising damp and sea spray are generally considered to be the only sources of sulphates, while the effects of sulphur of atmospheric origin on these materials are almost completely ignored.
In an effort to fill the gap in knowledge, samples of ancient and modern mortars were collected at Italian, Spanish and Belgian modern historic and archaeological sites. The samples were analysed in order to throw light on the effects of atmospheric sulphation.
The Authors present a synthesis of the characteristics of the samples analysed, together with an assessment of the damage encountered on sample surfaces as a result of the reaction between the mortars and atmospheric pollutants
WEATHERING AND MULTIPOLLUTANTS AGENTS IMPACT ON EARTH ARCHITECTURE:DAMAGE PROCESSES AND VULNERABILITY
No full textStrategie di caratterizzazione del particolato atmosferico per la protezione del patrimonio monumentale in aree urbane
No full textPer una nazione come l’Italia, che possiede gran parte delle opere d’arte mondiali, la conservazione e la salvaguardia dei beni culturali costituisce un obiettivo di primaria importanza. In quest’ottica si colloca lo studio dell’impatto ambientale sul Battistero di Firenze, situato nel centro urbano della città, realizzato attraverso il campionamento dell’aerosol atmosferico presso due delle tre porte dell’edificio, ovvero Porta Nord, esposta direttamente al traffico veicolare, e Porta Sud, influenzata indirettamente dalle emissioni veicolari. Allo scopo di confrontare la composizione del particolato atmosferico in prossimità delle due porte con quella della zona circostante, un terzo campionamento è stato effettuato sul tetto del Museo dell’Opera del Duomo, sito considerato come background dell’area. Del particolato totale sospeso sono stati misurati la concentrazione in massa in atmosfera, la componente ionica solubile e il carbonio non carbonatico. I risultati ottenuti indicano nei processi di combustione le principali sorgenti di particolato atmosferico nel centro di Firenze. Presso la Porta Nord del Battistero, le emissioni da traffico veicolare contribuiscono in modo rilevante alle concentrazioni degli inquinanti misurati. Inoltre, lo studio dimostra che, anche all’aperto, il flusso di visitatori incrementa la quantità d’aerosol atmosferico, influenzandone la composizione. Ogni monumento situato all’aperto è quindi esposto agli agenti inquinanti caratteristici della zona in cui è ubicato e solo un ampio monitoraggio locale può fornire i dati necessari per individuare strategie idonee alla protezione e conservazione del patrimonio culturale
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
Blackening as major atmospheric pollution effect on monuments.
No full textThe effects of air pollution on monuments and historical buildings have been studied over the last decades. The burning of fossil fuels produces gases, smoke and particulate carbonaceous matter that deposit on building surfaces and react with the underlying calcareous materials to form a damage layer. Carbonaceous particles have a catalytic effect on CaSO4•2H2O formation and the ensuing surface blackening on building exteriors. Considering the trends of major air pollutants, e.g. SO2, NOx and particulate, the increase in particle concentrations in urban area is threatening and will threaten the protection of cultural heritage in the future. For this reason, particular attention has been focused in recent years on the impact of carbonaceous particles on surfaces of artistic interest, with the aim of assessing their contribution in terms of carbon quantification.
Venice is presented as case of study and, in particular, the Corner Palace on the Canal Grande. The carbon fractions were discriminated and measured following a chemical-thermal methodology specifically developed for damage layer specimens. The resulting data show that the evaluation of pollution impact requires the quantification of the carbonaceous particles which are responsible of black crust formation and, particularly, elemental carbon, as tracer of anthropogenic deposition
Chemical–Thermal Quantitative Methodology for Carbon Speciation in Damage Layers on Building Surfaces
No full textThe issue of environment protection, including the conservation of the monumental heritage worldwide, is related to atmospheric pollution, and its future therefore depends on air pollutant reduction. Carbonaceous particles emitted by combustion processes are the main factors responsible for the blackening of buildings. The identification and evaluation of the carbon species constituting the non carbonate fraction of total carbon in damage layers, particularly in urban areas, are required in order to investigate atmospheric deposition on building surfaces. Since non carbonate carbon contains organic and elemental carbon originating from various human activities, its measurement and speciation are crucial to the protection and conservation of monuments and ancient masonry, playing an important role both in the proposal of mitigation strategies and in the definition of conservation treatments. The availability of a correct, accurate and reproducible analytical method for a complete carbon balance is essential in studying the effects of atmospheric pollutants on the environment, including those affecting cultural heritage. A chemical-thermal methodology was set up, and its sensitivity, accuracy, repeatability and reproducibility were tested on appropriate standard samples of composition similar to the black crusts on stones and mortars. The results indicate that the technique satisfactorily distinguishes among carbon species, particularly those of anthropogenic origin, allowing a reliable evaluation of their quantities in damage layers. In view of the difficulties encountered in applying the thermo-optical methods adopted for the measurement of carbon filters, the proposed methodology contributes to filling the current gap in suitable and reliable analytical procedures in the field of cultural heritage protection
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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