1,720,960 research outputs found
Le Produzioni ceramiche da fuoco tardoantiche altomedievali dai siti della Sardegna settentrionale: indagini morfologiche, cronologiche, archeometriche
No full textBeginning from the IV-V centuries AD, in the ceramic contexts of many sites of Western Mediterranean, appears the presence of handmade cooking wares. In the following centuries, above all between V and VI centuries, this presence is strengthened, up to monopolize the quantitative data of pottery reserved for cooking. Traditional archaeological studies, in absence of archaeometrical analysis, has interpreted this phenomenon as a return to local production, to the lack of imported production and the reorganization of the classical Mediterranean commercial network. The instability of the morphological classification of pottery production, has often determined the scarce scientific interest of it in the study of statigraphies. However, beginning from the comparison of research carried out on the sites of the Iberian peninsula, Africa, France, Italy and the islands of the Western Mediterranean, has emerged that some handmade cooking wares are recurrent in distant sites and separated by sea. Through archaeometrical
analysis have been identified some fabrics, which are incompatible with the geology of the discovery site. The inclusion of Sardinia in this line of investigation was natural and not more postponed. It is because this pottery is very common in late antique phases, and because it was assumed a Sardinian origin for some of the fabrics identified in Mediterranean archaeological sites. This investigation has been organized toward a symbiotic study of published and unpublished results of pottery materials coming from the site ofTurris Libisonis-Porto Torres (SS)
Nanostructured materials based on the integration of ferrocenyl-tethered dendrimer and redox proteins on self-assembled monolayers: an efficient biosensor interface
No full textIn this paper we report the use of ferrocenyl-tethered dendrimer (Fc-D) as an electrode modifier supported by a self-assembled monolayer coated gold surface. The pretreatment of electrodes with Fc-D allows the covalent immobilization of glucose oxidase. The resulting integrated hybrid system provides electrical contact between the redox center of the enzyme and the electrode, and improves the overall bioelectrocatalyzed oxidation of glucose. Cyclic voltammetry combined with surface plasmon resonance (SPR) is used to investigate the redox-induced orientation changes of ferrocene-tethered dendrimers and the optimal electrical wiring of the enzyme, depending on the length of the alkyl chain of the ferrocene-tethered groups. The amount of substrate controls the steady-state concentration ratio of Fc/Fc(+) in the film composition. Therefore, the SPR spectrum of the film is controlled by the reversible change in the refractive index of the enzyme-integrated redox film. The proposed method demonstrates a new procedure for developing a stable amperometric redox enzyme-based sensor by designing a new nanostructured material that control the biosensing performance
Laccase-based biosensor for the determination of polyphenol index in wine
No full textIn this work we have developed and characterized the use of Laccases from Trametes versicolor (TvL) and Trametes hirsuta (ThL) as biocatalytic components of electrochemical biosensors for the determination of polyphenol index in wines. Polyazetidine prepolimer (PAP) was used as immobilizing agent, multi-walled and single-walled carbon nanotubes screen-printed electrodes as sensors (MWCNTs-SPE and SWCNTs-SPE) and gallic acid as standard substrate. The amperometric measurements were carried out by using a flow system at a fixed potential of similar to 100 mV vs. silver/silver chloride electrode in Britton-Robinson buffer 0.1 mol L(-1), pH 5. The results were compared with those obtained with the Folin-Ciocalteau reference method. The results obtained in the analysis of twelve Italian wines put in evidence the better suitability of ThL-MWCNTs-based biosensor in the determination of the polyphenol index in wines. This biosensor shows fast and reliable amperometric responses to gallic acid with a linear range 0.1-18.0 mg L(-1) (r(2)=0.999). The influence of the interferences on both spectrophotometric and electrochemical measurements have been carefully evaluated. (c) 2009 Elsevier BM. All rights reserved
Study of ferrocene-modified G4-PAMAM dendrimer for reagentless biosensor development
No full textA fourth generation amine-terminated dendrimer (G4-PAMAM) was chemically functionalized through ferrocene (Fc) tethered groups (length of tether = C 11), The electrochemical properties of the new dendrimer molecule immobilized by using polyazetidine prepolymer (PAP) onto multi-walled carbon nanotubes (MWCNTs) screen printed electrode (SPE) surface, have been evaluated; then the Fc modified SPE was coupled to glucose oxidase (GOx) for the development of a reagentless glucose biosensor. The analytical performances of this device has been studied providing a linear response for one decade in the range 0.7-7.0 mM glucose with an RSD always below 4 %. © The Electrochemical Society
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
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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