1,720,965 research outputs found
Functional 3D printing: Approaches and bioapplications
Full text link3D printing technology has become a mature manufacturing technique, widely used for its advantages over the traditional methods, such as the end-user customization and rapid prototyping, useful in different application fields, including the biomedical one. Indeed, it represents a helpful tool for the realization of biodevices (i.e. biosensors, microfluidic bioreactors, drug delivery systems and Lab-On-Chip). In this perspective, the development of 3D printable materials with intrinsic functionalities, through the so-called 4D printing, introduces novel opportunities for the fabrication of “smart” or stimuli-responsive devices. Indeed, functional 3D printable materials can modify their surfaces, structures, properties or even shape in response to specific stimuli (such as pressure, temperature or light radiation), adding to the printed object new interesting properties exploited after the fabrication process. In this context, by combining 3D printing technology with an accurate materials’ design, functional 3D objects with built-in (bio)chemical functionalities, having biorecognition, biocatalytic and drug delivery capabilities are here reported
Cysteine-mediated synthesis of silver nanonets and their use for surface enhanced Raman scattering (SERS)
No full textHighly-branched plasmonic nanostructures are interesting substrates to be exploited in Surface-
Enhanced Raman Scattering (SERS) detection, as sources of efficient Raman ‘‘hot-spots”. In this study, L-cysteine is proposed as reducing/capping agents for the production of Ag nanonets showing different morphologies by varying the synthesis conditions. Substrates are coupled to PDMS membranes and characterized by Raman spectroscopy using 4-MBA to define their SERS performance. Experimental evidences confirm that only the thinnest structures are able to guarantee significant SERS responses
Real-Time Monitoring of the In Situ Microfluidic Synthesis of Ag Nanoparticles on Solid Substrate for Reliable SERS Detection
Full text linkA sharpened control over the parameters affecting the synthesis of plasmonic nanostructures is often crucial for their application in biosensing, which, if based on surface-enhanced Raman spectroscopy (SERS), requires well-defined optical properties of the substrate. In this work, a method for the microfluidic synthesis of Ag nanoparticles (NPs) on porous silicon (pSi) was developed, focusing on achieving a fine control over the morphological characteristics and spatial distribution of the produced nanostructures to be used as SERS substrates. To this end, a pSi membrane was integrated in a microfluidic chamber in which the silver precursor solution was injected, allowing for the real-time monitoring of the reaction by UV–Vis spectroscopy. The synthesis parameters, such as the concentration of the silver precursor, the temperature, and the flow rate, were varied in order to study their effects on the final silver NPs’ morphology. Variations in the flow rate affected the size distribution of the NPs, whereas both the temperature and the concentration of the silver precursor strongly influenced the rate of the reaction and the particle size. Consistently with the described trends, SERS tests using 4-MBA as a probe showed how the flow rate variation affected the SERS enhancement uniformity, and how the production of larger NPs, as a result of an increase in temperature or of the concentration of the Ag precursor, led to an increased SERS efficiency
A new versatile algorithm to extract particle’s features from FESEM images: method evaluation and a case study on rice kernels
Full text linkImage analysis approaches allow to quickly extract important information from images of diverse nature. Many techniques produce as a result images that contain regular and irregular objects. The ability of automatically extracting the objects and their related morphological features and properties is becoming fundamental, especially when the number of images to analyse is consistent.
In this context, a new algorithm able to extract a series of morphological features from FESEM images was developed. Starting from a case study on 54 varieties of rice kernels, 220 images were acquired, and the algorithm was coded with the aim of extracting information from the round-shaped starch particles naturally present in rice kernels. The algorithm constitutes of different steps to segment the images and identify the object shapes and boundaries. Once those objects are identified, the algorithm extracts their morphological features, the number of identified objects and the amount of empty spaces among those objects.
The developed algorithm is suitable for a rapid and automated analysis of several images, with the aim of extracting object-related morphological features and information about the general objects space disposition. The use of adaptive thresholds and correction steps allow to analyse images of different natures containing also defective and non-representative objects that will be automatically removed from the features calculation. In addition, to evaluate the algorithm performances, a Design of Experiment approach was developed to determine the effect of the input parameters choice on the algorithm output results, highlighting which parameters show a stronger effect on the output
Surface enhanced raman scattering active chips for mycotoxin detection in food matrices
Full text linkSurface-enhanced Raman Scattering (SERS) is an excellent analytical tool that can be used to develop assays
and biosensors for the sensitive detection of small molecules in complex samples, taking advantage of plasmonic
nanostructures. In this work, an aptamer was exploited to develop a competitive assay for Aflatoxin B1 (AFB1)
by means of SERS analysis. After the careful optimization of the SERS-based assay, its potentiality for food
safety assessment was demonstrated by detecting AFB1 in different extracts of AFB1-spiked slurry of hazelnut
below the threshold defined by the regulatory limits
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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