1,720,971 research outputs found
La pietra massiva nella progettazione - dalle caratteristiche dei materiali alle valenze energetico-architettoniche di involucri lapidei massivi “innovativi”
Full text linkLa pietra naturale per secoli ha avuto un ruolo centrale nel progetto di architettura ma con la diffusione del calcestruzzo e dell’acciaio è stata impiegata prevalentemente in elementi sottili di rivestimento. Attualmente, però, c’è stata nella cultura architettonica contemporanea una riscoperta della pietra massiva attraverso il recupero e l’attualizzazione della tecnica costruttiva tradizionale della muratura e la diffusione delle tecniche innovative della pietra armata precompressa e dei gabbioni. Molti progettisti sono tornati, infatti, ad impiegare la pietra in spessori rilevanti, spesso in combinazione con altri materiali, per realizzare pareti perimetrali verticali, coperture e strutture in elevazione. Il rinnovamento del linguaggio architettonico è legato al riconoscimento delle potenzialità della pietra massiva connesse a valori espressivi e di sostenibilità economica ed ambientale: l’uso massivo della pietra naturale, infatti, è motivato non solo dall’esigenza di integrarsi con il paesaggio o esprimere l’identità locale ma anche dalla possibilità di realizzare con costi e tempi di costruzione contenuti elementi tecnici durevoli, dotati di elevata inerzia termica, facilmente riciclabili o ottenuti attraverso il recupero o il riciclo di materiale lapideo di scarto. Questo rinnovamento è stato consentito dalle molteplici innovazioni che hanno interessato il settore lapideo. In particolare, la diffusione dei sistemi CAD/CAM/CNC, il passaggio dalla stereotomia alla stereotomia digitale legata anche a software di progettazione parametrica e la disponibilità di programmi di calcolo e di metodi di form-finding basati su modelli digitali e non più su modelli fisici hanno permesso di realizzare prodotti lapidei di forma complessa con tempi e costi di fabbricazione ridotti e di ampliare le possibilità di ricerca formale dei progettisti.
La prima parte della ricerca esamina alcuni dei metodi e degli strumenti innovativi che hanno contribuito alla riscoperta della pietra massiva nella cultura architettonica contemporanea e analizza, attraverso il riferimento a casi di studio, i caratteri delle tecniche costruttive della muratura, della pietra armata e dei gabbioni per definire un quadro di riferimento tecnologico-scientifico sui materiali lapidei: vengono messe a sistema, infatti, le conoscenze relative ai materiali lapidei naturali e artificiali (lapidei agglomerati; calcestruzzi realizzati con gli scarti di estrazione o di lavorazione dei lapidei naturali), alle tecniche di lavorazione, ai metodi e agli strumenti di progettazione e ai linguaggi progettuali contemporanei.
La seconda e la terza parte della ricerca evidenziano alcune delle potenzialità di involucri lapidei massivi innovativi. La seconda parte della ricerca è dedicata allo studio scientifico-quantitativo dell’importanza dell’inerzia termica del materiale per il miglioramento delle condizioni di comfort termico interno e per la riduzione della domanda energetica degli edifici: attraverso simulazioni dinamiche annuali eseguite su un edificio residenziale di progetto sono stati valutati, infatti, i vantaggi prestazionali connessi con l’adozione, in diverse condizioni climatiche, di involucri massivi innovativi rispetto ad involucri lapidei tradizionali. La terza parte della ricerca, invece, indaga le valenze prestazionali e i caratteri architettonici di involucri edilizi a gabbioni. Attraverso simulazioni dinamiche annuali eseguite sullo stesso modello studiato nella seconda parte della tesi, vengono individuate delle correlazioni tra le principali caratteristiche di involucri multistrato a gabbioni e la prestazione termico-energetica dell’edificio: sulla base delle correlazioni individuate vengono definite delle indicazioni per valutare l’appropriatezza delle scelte compiute in fase di progettazione della soluzione costruttiva al fine di minimizzare la domanda energetica per il riscaldamento e il raffrescamento dell’edificio e migliorare le condizioni di comfort termico interno. Infine, attraverso il riferimento ad architetture contemporanee e l’individuazione di analogie figurative con opere e manufatti realizzati con tecniche costruttive tradizionali, vengono evidenziati i caratteri architettonici di involucri edilizi a gabbioni legati alle possibili tipologie di texture del riempimento litico dei moduli costruttivi e alle specifiche soluzioni progettate per la risoluzione di problemi connessi con l’inserimento di aperture vetrate o di altri materiali di rivestimento e con lo smaltimento dell’acqua piovana
Physicochemical and biological characterization of magnetic nanoparticles for biomedical applications
Full text linkThe overall goal of this project was the biological characterization by in vivo and in vitro testing of magnetic nanoparticles that can be used for various applications. The aim of this work was to understand which of the synthesized magnetic nanoparticles could be more suitable to be used as a carrier or platform for various applications in different scientific fields. Two different kinds of magnetic nanoparticles were developed: naked iron-oxide nanoparticles and silica or silica-based coated nanoparticles (core shell-type nanoparticles). Magnetic nanoparticles were prepared using a coprecipitation method. The structure, phase composition, physicochemical and surface properties, magnetic susceptibility, and release in vitro of MNPs were characterized by transmission electron microscopy, x-ray diffraction, scanning electron microscopy-energy dispersive x-ray spectroscopy, and a vibrating sample magnetometer. In vivo toxicity, in vitro toxicity, ROS production and genotoxicity were investigated. Therapeutic effects were evaluated by cell viability assays and flow cytometry assays. The tools developed in this thesis spanned a range of physical-chemical, biological and magnetic aspects and incorporate innovations on a nanometric range of scales. MNP-based technologies appear to hold a significant potential for a myriad of biomedical applications and the toxic potential of MNPs cannot be overlooked. For this reason we carried out different physicochemical and biological characterization of MNPs to identify a safe dose and formulation of MNPs. Understanding the relationship between the physicochemical properties of MNP constructs and their behavior will induce full translational potential of these nanoparticles. The magnetic nanoparticles prepared in this study have good biocompatibility and are suitable for further application in tumor hyperthermia
Tissue-engineered skin substitutes: an overview
No full textExtensive skin loss and chronic wounds are still a significant challenge to clinicians: even if injured epidermis is normally able to self-renew, deep injuries can cause negative regulation of the wound healing cascade, leading to chronic wound formation. Skin-autografting surgical procedures are often limited by the poor availability of healthy tissue, whereas the use of non-self-tissues for allografts presents some severe risks. Tissue-engineered skin substitutes have recently become viable as a suitable alternative to auto- and allografts. However, biologists, biochemists, and technical engineers are still struggling to produce complex skin substitutes that can readily be transplanted in large quantities. The ambitious goal is now to construct a dermoepidermal substitute that rapidly vascularizes and optimally supports a stratifying epidermal graft on a biodegradable matrix. This review analyzes these aspects in light of the available literature and the authors' experienc
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
In vitro biological validation and cytocompatibility evaluation of hydrogel iron-oxide nanoparticles
Full text linkSuperparamagnetic iron oxide nanoparticles (MNPs) have recently been investigated for their excellent biocompatibility as well as multi-purpose biomedical potential with promising results, owing to their ability to be targeted and heated by magnetic fields. In this study, novel hydrogel, chitosan Fe3O4 magnetic nanoparticles were synthesized for possible use for induced magnetic hyperthermia, and targeted drug delivery. The coating of iron oxide nanoparticles plays a key-role to efficiently improve internalization of nanoparticles in many cell types. Targeting is also highly desirable for these applications. In this regard hydrophilic coating like chitosan was used to improve drug release. Uncoated (Fe3O4)and chitosan-coated iron oxide nanoparticles (CS-Fe3O4) were synthesized and characterized from the biological point of view. The aim of this study was to provide an in vitro evaluation of the cytocompatibility of Fe3O4 and CS-Fe3O4 MNPs by using different in vitro evaluation tests. In this context, the cytocompatibility and cytotoxic effects of uncoated and hydrogel chemically-engineered chitosan-coated iron oxide NPs were investigated according to the ISO standard 10993-5:2009. Fe3O4 and CS-Fe3O4 NPs were tested on human mammary epithelial cells (MCF-10A) by using direct and not direct contact cytotoxicity evaluation tests, by evaluating influence of the iron particles on the cytoskeleton with phalloidin/DAPI staining and in vitro cellular iron uptake with Perl’s Prussian blue staining. The results indicate that uncoated and chitosan-coated iron oxide nanoparticles are cytocompatible, without negative influence on the cytoskeleton or higher accumulation of iron in the cytoplasm. Therefore, it is encouraging that our data suggest uncoated and chitosan-coated iron oxide nanoparticles have satisfactory proliferative and viability effects on MCF-10A cells. In conclusion data suggest that both MNP types may be differently aimed in biomedical application in relation to the dose, acting as biocompatible materials, as component of scaffolds, or as a device for theranostics.publishedVersio
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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