1,720,961 research outputs found
Functional nanostructured surfaces with biocidal and antiviral properties
Full text linkScoperta all'inizio degli anni 2000, quella dei carbon-dots è una famiglia di nanomateriali a base di carbonio che ha riscosso un grande interesse da parte della comunità scientifica per le loro eccellenti proprietà. Inizialmente studiati per le loro proprietà ottiche (in particolare la fluorescenza), i campi di applicazione sono diventati molti nel corso degli anni, trovando maggiore impiego nel campo biomedico, come ad esempio nel bioimaging, nella terapia fotodinamica e nel controllo dell'inibizione e della proliferazione dei microrganismi, tra i tanti.
L'obiettivo di questo lavoro di dottorato è stato quello di utilizzare queste nanoparticelle, i carbon-dots, per funzionalizzare delle superfici e conferire loro proprietà antimicrobiche. I carbon-dots sintetizzati a partire da un aminoacido, la glicina, e da due co-precursori, l'1,5-diaminaftalene e l'acido glicirrizico, hanno mostrato interessanti proprietà antimicrobiche. In particolare, i dots sintetizzati con glicina e 1,5-diaminaftalene hanno mostrato un'eccellente attività antivirale contro due varianti del SARS-CoV-2, il ceppo originale e il ceppo delta. Mentre i dots sintetizzati da glicina e acido glicirrizico hanno mostrato un'interessante suscettibilità antibatterica contro i batteri gram-positivi, S. aureus ed E. faecium. Le caratterizzazioni effettuate, come TEM, FTIR, XPS e NMR, hanno permesso di comprendere le principali caratteristiche strutturali di questi dots, mentre con l'EPR è stato possibile capire il meccanismo dell'azione antimicrobica di questi nanomateriali, identificando la promozione dei ROS da parte di quest'ultimi. Infine, i dots che hanno mostrato attività antivirale sono stati utilizzati per funzionalizzare le superfici a base di silicio attraverso un approccio chimico covalente, mantenendo inalterate le loro proprietà antivirali anche dopo la funzionalizzazione. I dots che hanno mostrato attività antibatterica, invece, sono stati utilizzati per funzionalizzare una superficie self-standing a base di PVA, incorporando i materiali all'interno di una matrice polimerica. Questo sistema ha mostrato un'interessante applicazione per preservare l'integrità di alimenti freschi, come la frutta, aumentandone la durata di conservazione.Discovered in the early 2000s, that of carbon-dots is a family of carbon-based nanomaterials that has received a great interest from the scientific community because of their excellent properties. Initially studied for their optical properties (especially fluorescence), the fields of application have become many over the years, finding greater use in the biomedical field, such as in bioimaging, photodynamic therapy, and control on inhibition and proliferation of microorganisms, among many others.
The goal of this doctoral work was to use these nanoparticles, the carbon-dots, to functionalize surfaces to confer them antimicrobial properties. The synthesized carbon-dots, starting from an amino acid, glycine, and two co-precursors, 1,5-diaminonaphthalene and glycyrrhizic acid, showed interesting antimicrobial properties. Specifically, dots synthesized with glycine and 1,5-diaminonaphthalene showed excellent antiviral activity against two variants of SARS-CoV-2, the original strain and the delta strain. Whereas dots synthesized from glycine and glycyrrhizic acid showed interesting antibacterial susceptibility against gram-positive bacteria, S. aureus and E. faecium. Characterizations carried out, such as TEM, FTIR, XPS, and NMR, allowed to understand the main structural features of these dots, while with EPR, it was possible to understand the mechanism of antimicrobial action of these dots, identifying the promotion of ROS by these nanomaterials. Finally, the dots that showed antiviral activity were used to functionalize the silicon-based surfaces through a covalent chemical approach, keeping their antiviral property unaltered, even after functionalization. The dots that showed antibacterial activity, on the other hand, were used to functionalize a self-standing PVA-based surface by embedding the materials within a polymer matrix. This system showed interesting application in preserving the integrity of fresh foods, such as fruits, by increasing their shelf-life
Application of IR and UV–VIS spectroscopies and multivariate analysis for the classification of waste vegetable oils
Full text linkDue to the ever-increasing worldwide interest in the exploitation of waste vegetable oils, the development of
analytical tools able to detect their adulteration with edible oils, is considered a priority for the scientific and
industrial community. In this work, edible and waste vegetable oils have been analysed by Fourier Transform-
InfraRed (FT-IR) and Ultraviolet-Visible (UV–VIS) spectroscopies and the corresponding spectral data subjected
to statistical multivariate analysis for classification purposes. In particular, Principal Component Analysis
(PCA) and Partial Least Square Discriminant Analysis (PLS-DA) were performed in order to develop an analytical
tool which is able to distinguish between edible and waste vegetable oil. Qualitative analysis of the spectra
suggested FT-IR and UV–VIS as the more suitable techniques to distinguish between wastes and edible samples.
Also, statistical multivariate analysis revealed that FT-IR-based methodology is more adequate for the target,
even if the elevated sensibility of the method produces an undesired distinction between edible oils of the same
type. Finally, further attempts on UV–VIS data obtained in reflection mode allowed to produce a good dataset
which after statistical treatment gave a clear differentiation between edible and waste oil samples
Raman spectroscopy and multivariate analysis for the waste and edible vegetable oil classification
No full textTwelve samples of waste cooking oil (WCO) were prepared by four different deep-frying procedures. The edible and the waste oil samples were characterised by Raman spectroscopy, revealing few and almost negligible differences between them. Therefore, the possibility of classifying the different groups of samples by extracting valuable data from the Raman spectra through statistical multivariate analysis was explored. Even if the number of samples was not enough to draw definitive conclusions, unsupervised principal component analysis (PCA) and supervised partial least square discriminant analysis (PLS-DA) conducted on the raw Raman signals, allowed to distinguish within edible and waste vegetable oil, and to select the most relevant combination of variables associated with each family. Using sparse partial least square discriminant analysis (S-PLS-DA), we determined a chemical fingerprint characteristic of each sample by creating a Variable In Projection (VIP) plot. The methodology herein presented could find relevant application in the detection of waste adulteration in vegetable oils sold for industrial purposes other than food
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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