435 research outputs found
Flowable Mixtures of Treated Soils for Repairing Damage Caused by Burrowing Animals
Get PDFThe adoption of flowable mixtures of treated soils is suggested as a sustainable solution for repairing the damage caused by burrowing animals in the Po River embankments. Soil from damaged sites is proposed to be mixed with lime or cement, other additives, and water in order to obtain mixtures with an adequate compromise between viscosity—which is crucial for flowing the mixture into the hole with site machines—and shrinkage that might occur over time according to the hole boundary conditions. Injections of soil-treated mixtures must guarantee hydraulic and mechanical continuity with the existing embankment and reduce shrinkage phenomena that frequently occur with cement–bentonite grout, which is commonly used for this purpose. This study presents an interdisciplinary experimental programme in the search for the best formulation among several recipes of mixtures of soils, collected from four embankments of Po River or its tributaries and treated with lime or cement, different percentages of water, and other additives. The mixtures, after soil classification and viscosity determinations, were then used to create samples for which shrinkage and erosion susceptibility were estimated, respectively, through a non-standard volume measurement procedure and crumb tests. An abacus will be then proposed in order to give, as a first estimation, applicative indications on the best recipe among the investigated mixtures
Assessing River Embankments Stability to FLoods through Unsaturated Centrifuge Testing In transient Seepage conditions - RES FLUCTIS
No full textRiver flood is considered one of the most relevant natural hazards in Europe in terms of economic and human life losses and is frequently due to severe damages experienced by retaining water earthworks, under extreme weather events. Moreover, the risk of breach-induced inundations is expected to increase for many river basins in a climate change scenario and a growing land urbanization. In this framework, a reliable assessment of existing river embankment safety conditions, in serviceability and limit states of operation, represents a key aspect to enhance the resilience of these critical infrastructures (CI). A satisfactory solution to this problem cannot disregard the partially saturated state of the earthfill, neither the role of river stage fluctuations on the seepage process within the embankments. Nevertheless, in the current engineering practice, these aspects are frequently neglected, mainly due to the difficulties in estimating the actual suction distribution and shear strength, providing erroneous conclusions on the effective safety margins towards possible slope instability and overall collapses.
The proposed research project aims at contributing to a better understanding of the effect of time-dependent hydraulic loadings on the stability of the CI through a series of centrifuge tests. The small-scaled physical model will be characterized by a compacted embankment made of a natural silty sand, representative for a tributary river bank, overlying a homogeneous clay foundation layer. To investigate the hydro-mechanical behaviour and the possible failure mechanisms of the CI induced by transient and stationary hydraulic boundary conditions, pore pressure transducers, displacement sensors and high-resolution cameras will be used to monitor the centrifuge tests comprehensively. The 2-week experimental campaign will include model preparation, execution and dismantling of two tests. The project will provide valuable recommendations to improve standards for the stability assessment of river embankments and support the development of more reliable flood risk reduction strategies
(Ri-)Scrivere di santi: sulle tracce di Agnese
No full textL’articolo, seguendo una sollecitazione di Gennaro Luongo, recentemente scomparso, si interessa al dossier agiografico di Agnese. L’autrice lo ripercorre fra storia e leggenda, documenti letterari e testimonianze monumentali, iconografia e pratiche devozionali. Ciò le consente di mettere in evidenza le trasformazioni e continue ri-funzionalizzazioni del personaggio, nonché di avanzare alcune ipotesi sulle ragioni che presiedettero a questi continui processi di rilettura.The article following a solicitation by Gennaro Luongo, recently deceased, deals with the hagiographic dossier of Agnese. The author traces it between history and legend, literary documents and monumental evidences, iconography and devotional practices. This allows her to highlight the transformations (modifications) and continuous re-functionalizations of the character, as well as to advance some hypotheses on/regarding the reasons that presided over these continuous re-reading processes
A naked eye aggregation assay for Pb2+ detection based on glutathione-coated gold nanostars
No full textGold nanostars (AuNS) with a mean hydrodynamic size of 40 nm, obtained with a seed-growth approach using a zwitterionic surfactant (laurylsulfobetaine, LSB), were successfully coated with glutathione (GSH), obtaining a stable and purified solid product which can be easily stored and re-dissolved on need in 0.1 M aqueous solution of Hepes buffered at pH 7. Upon exposure to micromolar concentrations of Pb2+ cation, the GSH-coated nano-objects undergo a fast aggregation followed by sedimentation leading to complete precipitation in about an hour. The subsequent disappearing of the intense LSPR extinction can of course be followed spectrophotometrically but, most importantly, can be easily detected with the naked eye. No signs of this event are noticed when other divalent cations are added to the colloidal suspension in the same condition. A careful investigation was performed to study this selectivity and the behaviour of aggregation as a function of time and Pb2+ cation concentration. We demonstrate that an easy, rapid, instrument-free, visual detection of micromolar levels of Pb2+ is thus possible with this assay, showing a good selectivity towards other investigated metal cations
Giuseppe Dessí
Get PDFTwenty-five years after the death of one of the most refined and secluded writers of the second half of the 20th century, the complete catalogue of works and author papers in the Giuseppe Dessí Collection is available, thanks to the work and philological expertise of Agnese Landini. The filing of the material, deposited in the Contemporary Archives of the Gabinetto Vieusseux in Florence, allows to retrace the complete bibliography of the published and unpublished works of the Sardinian writer and, while telling the story of a narrative path through documents, it eases access to notes and drafts of novels, short stories, plays, anthologies, translations, essays, poems, interviews
Osservazioni su un apografo della farrago pucciana (Roma, Biblioteca Casanatense, vol. inc. 694)
No full textThis paper offers an analysis of the marginalia to Catullus’ poems contained in a Roman incunable (Biblioteca Casanatense, Vol. Inc. 694). Most of these notes can be traced back to the so called ‘farrago pucciana’, annotations to Catullus, Tibullus and Propertius by Francesco Pucci, a disciple of Poliziano. These marginalia were held in high esteem by 16th-century humanists, and over twenty copies of them survive today. In this paper the exemplar of the Casanatense incunable is identified and some hypotheses regarding the author of this copy and his connections with Piero Vettori are discussed, along with an outline of the tradition of the farrago pucciana
A naked eye aggregation assay for Pb2+ detection based on glutathione-coated gold nanostars
No full textGold nanostars (AuNS) with a mean hydrodynamic size of 40 nm, obtained with a seed-growth approach using a zwitterionic surfactant (laurylsulfobetaine, LSB), were successfully coated with glutathione (GSH), obtaining a stable and purified solid product which can be easily stored and re-dissolved on need in 0.1 M aqueous solution of Hepes buffered at pH 7. Upon exposure to micromolar concentrations of Pb2+ cation, the GSH-coated nano-objects undergo a fast aggregation followed by sedimentation leading to complete precipitation in about an hour. The subsequent disappearing of the intense LSPR extinction can of course be followed spectrophotometrically but, most importantly, can be easily detected with the naked eye. No signs of this event are noticed when other divalent cations are added to the colloidal suspension in the same condition. A careful investigation was performed to study this selectivity and the behaviour of aggregation as a function of time and Pb2+ cation concentration. We demonstrate that an easy, rapid, instrument-free, visual detection of micromolar levels of Pb2+ is thus possible with this assay, showing a good selectivity towards other investigated metal cations
Per la biografia di fr. Iacopo Passavanti OP (1302 ca.-1357)
No full textIacopo Passavanti is currently known for his sermons and as the author of one of the oldest theological treatises, which was redacted both in Latin and Vernacular. However, he was also a leading member of the Order of Preachers and a spokesman of an innovative reli- gious and cultural project which, it seems, he held in common with the entirety of the Order of St. Dominic. With this paper, we intend to recreate the friar’s biography and shed light on his works. Thus, we will proceed with a critical reading of the documents that concern him, which we organized, for the occasion, in a new Diplomatic Code
Promoting reading skills in Latvian language lessons in primary school in the 3rd grade
No full textDarba temats: Lasītprasmes sekmēšana latviešu valodas stundās sākumskolā 3. klasē Darba autore: Agnese Ozoliņa Darba vadītāja: Antra Randoha Darba mērķis: teorētiski un praktiski izzināt pedagoģiskās metodes lasītprasmes sekmēšanai sākumskolas 3. klasē. Darba teorētiskajā daļā tika analizēta teorētiskā literatūra par lasītprasmes jēdziena skaidrojumu. Darba autore apkopoja lasītprasmes sekmēšanas stratēģijas un metodes. Izpētīts sākumskolas vecuma bērnu attīstības īpatnības. Darba empīriskajā daļā tika izveidots pētījuma plāns un aprakstītas pētīšanas metodes. Darba autore izveidoja skolēnu raksturojumu, aprakstot pētāmo problēmu. Tika izveidoti lasītprasmes vērtēšanas kritēriji. Lai sekmētu skolēnu lasītprasmi tika izmantotas dažādas metodes un stratēģijas, gan ārpusskolas aktivitātēm, gan mācību stundas ietvaros. Iegūtie rezultāti tika analizēti un salīdzināti. Darba apjoms: 48 lapaspuses, 12 attēli, 4 tabulas, 32 literatūras avoti. Atslēgvārdi: 3. klase, skolēni, lasītprasme, latviešu valoda, skola.The topic of the work: Promoting reading skills in Latvian language classes in primary school in the 3rd grade Author of the work: Agnese Ozoliņa Supervisor: Antra Randoha The purpose of the work: to theoretically and practically learn the pedagogical methods for promoting reading skills in the 3rd grade of primary school. The theoretical part of the work analyzed the theoretical literature on the explanation of the concept of literacy. The author of the paper summarized the strategies and methods of promoting literacy. Peculiarities of development of children of primary school age have been studied. In the empirical part of the work, only a research plan is created, and research methods are described. The author of the work created a description of the students, describing the problem under study. Evaluative literacy assessment criteria were created. Various methods and strategies were used to promote students' reading skills, both in extracurricular activities and in the classroom. The obtained results were analyzed and compared. Work volume: 48 pages, 12 images, 4 tables, 32 literature sources. Keywords: 3rd grade, students, literacy, Latvian language, school
Sand boil observations and geotechnical characterization of river embankments for the development of a backward erosion piping database
Get PDFSand boil formation at the toe of river embankments is the typical manifestation of initiation and progression of an internal erosion process known as backward erosion piping, which is recognized to be a major concern in many river systems worldwide. In Italy, more than 130 sand boils have been detected along the Po River, many of them experiencing recurrent reactivations during high-water events. As a consequence of such widespread occurrence and the risk for the safety of the surrounding territory and human activities, the development of a sand boil database has been increasingly seen as an essential tool for identifying triggering conditions and giving priorities for the implementation of mitigation measures. In recent years, as part of the activities of the European Project LIFE SandBoil, a GIS-based web application was developed in order to catalogue the sand boils observed along the Po River. The database allows keeping records of a comprehensive set of information, e.g. geometry of the river embankments, subsoil stratigraphy, data on the sand boils, and characteristics of high- water events. Taking a piping-prone cross-section along the Po River as reference, the paper aims at describing the main features of this versatile and flexible tool, which is meant to help in understanding the conditions causing initiation and the sand boil dynamics, as well as to support flood risk management against backward erosion piping
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