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Ettringite and thaumasite: A chemical route for their removal from cementious artefacts 总被引：1，自引：0，他引：1
The present paper reports a new method for converting ettringite and thaumasite in non-expansible and insoluble phases, for its application in the restoration of concrete artefacts subjected to deterioration through sulphate attack. The salts were synthesized by different processes and, after characterization by means of XRD, FT-IR and optical microscopy, were treated with a series of chemicals in order to induce their decomposition. In particular, different solutions containing barium nitrate, barium hydroxide and ammonium oxalate were used to achieve the complete transformation of both phases in barite, witherite, scarbroite and whewellite. Barium hydroxide seemed to be the most appropriate reactant because the others could give rise to efflorescence within the pores of the mortars by leaving free nitrate or sulphate ions inside the materials. The experimental technique was also tested on two concrete samples collected from the bell-tower of St. Nicholas’ Cathedral in Nicosia (Sicily) with encouraging results. 相似文献
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Adobe is a construction technique that uses raw earth mixed and moulded to form sun-dried blocks to realize a bearing wall. The recent discovery of adobe walls belonging to a Republican domus sited in Suasa (Ancona, Italy) was the starting point of the present work. The research was developed through an experimental approach, in order to characterize the mechanical behavior of this type of walls: firstly some adobe blocks similar to the original ones were reproduced by using the soil directly came from the archaeological site near the adobe walls and adding straw to reduce hygrometric shrinkage and coarse sand, taken from a local quarry, as a stabilizer, as Romans were used to do. Then, after a seasoning period of 4 months, four adobe walls were produced to be tested by compression and shear. From compression tests, maximum strength, first cracking compression stress, Young modulus and breaking manner were evaluated. As well, compression results show a possible two-storey structure of the earthen Republican domus. In fact, it appears that the stress from the two-storey load analysis is lower than the first cracking compression stress. From the shear tests, a proportional law seems to regulate the relation between the maximum value of the mean tangential tensions and the vertical compression the sample is subjected to. This could be the starting point for a future seismic analysis. 相似文献
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Malgorzata?ZiebaEmail author Ettore?Bolisani Marco?Paiola Enrico?Scarso 《知识管理研究与实践》2017,15(2):282-293
The paper analyses the activity of research for “innovation knowledge”—here defined as knowledge that can lead to the introduction of service innovations—by Knowledge-Intensive Business Services (KIBS) companies. It proposes a classification of the possible search approaches adopted by those companies based on two dimensions: the pro-activity of search efforts and the source primarily used. Such classification is then discussed on the basis of the findings of a multiple case-study investigation involving 15 Italian and Polish KIBS companies. The study confirms that KIBS firms follow various approaches to acquire knowledge for innovation: some companies adopt a passive behaviour (i.e. innovative ideas come as a kind of side effect of their daily business activities), while others an active one (namely, they actively search for new ideas originating from various sources); some rely more on internal resources (employees, in-house R&D, internal documents, etc.), while others on external sources (clients, suppliers, service providers, universities, etc.). The results of the study have implications both for research and management that are discussed in the conclusions. 相似文献
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Enrico Quagliarini Enrico Esposito Antonio del Conte 《Journal of Cultural Heritage》2013,14(2):122-128
Correct interventions on cultural heritage should have as their starting point an accurate diagnosis of its health, in order to design a compatible care. NDTs seem to offer a promising way in this sense. This paper deals with the combined use of IRT and LDV for the investigation of historical thin vaults made by timber arches, reeds, and plaster and it demonstrates that they can effectively support a deeper knowledge of these vaults as it concerns the presence of detached areas among the different mortar layers of the plaster and of detached areas among the mat of reeds and the nailed connection with the wooden bearing elements. This is a very important goal because these ND methodologies can be employed only on the lower surface of these vaults and sufficiently far from it, and they do not have any mechanical interaction with the historical, eventually frescoed or stuccoed, plaster, thus saving money and time. 相似文献
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Enrico Clerici 《Endeavour》1985,9(4):156-160
Although organ transplants, especially of kidneys, are now widely practised surgical procedures, the problem of preventing rejection is still not solved. This article considers why — since organ transplantation is an entirely artificial process — the body nevertheless has a complex immunological mechanism for rejecting all intruding foreign implants. 相似文献
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Giorgio Bignami Enrico Alleva Luigi Amorico Luigi De Acetis Valerio Giardini 《Learning & behavior》1985,13(4):439-450
Acquisition of two-way avoidance by mice was slower with a light CS than with a buzzer CS, with punishment of intertrial responses than without punishment, and with a short CS-CS interval than with a long CS-CS interval (30 vs. 60 sec). Light-cued avoidance was little affected by shock level (.35–1.5 mA), whereas mice trained with the buzzer CS learned faster at 1.5 mA. Animals required to move away from light or toward light showed comparable rates of acquisition. Other CS, US, and apparatus variables (directionality of cue, maximal shock duration, and presence vs. absence of a central partition in the shuttlebox) interacted in a complex fashion with those already mentioned. This resulted in widely differing performances in what may superficially appear to be different versions of the same task. The differences in mouse and rat responses to some of the variables can contribute to an understanding of the interactions between organismic and test factors and the relative explanatory value of alternative avoidance models. 相似文献
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Caviola Sara Toffalini Enrico Giofrè David Ruiz Jessica Mercader Szűcs Dénes Mammarella Irene C. 《Educational Psychology Review》2022,34(1):363-399
Educational Psychology Review - The relationship between anxiety and mathematics has often been investigated in the literature. Different forms of anxiety have been evaluated, with math anxiety... 相似文献