1,720,979 research outputs found
Demonstration of fluorescence enhancement: via Bloch surface waves in all-polymer multilayer structures
Full text linkAn all-polymer photonic structure constituted by a distributed Bragg reflector topped with an ultrathin fluorescent polymer film has been studied. A Bloch surface wave resonance has been exploited to improve pumping efficiency. A strongly polarization and angle dependent fluorescence signal is found with respect to the light pumping beam and the emitted wavelength. Matching the most favorable condition for the pump coupling and the collection geometry, the signal obtained from the structure appears to be two orders of magnitude larger than the one of the bare emitting film
Optical Properties of Polystyrene opals infiltrated with cyanine dyes in the form of J-aggregates
No full textWe report preliminary data on the infiltration of polystyrene opals with cyanine dye water solutions, which are known to form J-aggregates. Different approaches are used to infiltrate cyanines inside opals. The degree of infiltration is evaluated by scanning and transmission electron microscopy as well as micro reflectance spectroscopy. Data show that in spite of the low wettability of polystyrene with water solutions, some infiltration can be achieved. Even though this degree of infiltration is still not enough to observe strong modification on the photonic band structures, further strategies to improve it are in progress
Dispositivo per il rilevamento di composti molecolari basato su risonanza plasmonica di superficie
No full textIn recent years, several approaches have been developed to carry out biosensors based on Localized Surface Plasmon Resonance (LSPR). However, the high costs of nanostructures fabrications and absence of autonomous portable devices strongly limit the extensive use of LSPR biosensors outside the research laboratories.
We designed, carry out and tested a novel low cost, multiparametric stand-alone LSPR imaging instrument for biosensing applications. This compact device (15 x 6 x 17 cm size and < 500g weight) consist on a nanohole array biochip integrated with a microfluidic layer and an elaboration system. An optical apparatus focuses a light beam from an IR LED source and a digital image sensor captures the reflected light from the biochip surface. The signals are processed by the embedded ARM processor and showed in a touchscreen display by a friendly end-user application, without the use of other external computational devices.
Moreover, we propose an extremely simple analytical method to reduce image noise without any sophisticated temperature control or external luminosity change compensation.
The device sensitivity of 6 x 10-5 Refractive Index Unit (RIU) was proved using glycerol solutions with different concentrations. We demonstrated the feasibility of our system in biomolecular detection, by monitoring the Ab-PTX3 antibody, as a test revealing instrument potentialities in detection of antibodies.
The obtained results confirmed the potential usefulness of the proposed system in several biomedical applications such as medical diagnostic, immunoassays or fast mass screening without the aid of specialized laboratory or trained personne
A Novel Portable Surface Plasmon Resonance Based Imaging Instrument for On-Site Multi-Analyte Detection
No full textIn the last decade the need for portable Surface Plasmon Resonance (SPR) biosensors capable of on-site simultaneous multiple assays increased steadily. Several devices are available affected, however, by limitations in terms of costs, size, complexity and portability. A compact low-cost SPRi biosensor based on a novel method for multi-analyte detection is presented. The prototype consists of a nanohole array biochip integrated with a compact optics and an elaboration system. A CMOS image sensor captures reflected light from the biochip surface irradiated by a 830 nm LED. The entire system is managed by an ARM9 processor. The biosensor was able to detect a ~10-5 RIU change in the refractive index without analyte receptors at a glycerol concentration equal to 0.2%. Results are available in 14 seconds on LCD display and immediately stored to external SD memory. Preliminary experiments confirmed the strong biosensor's usability in a wide range of applications and field
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
Organic Flexible Photonic Structures for Amplified Light Emission
No full textWe report on the preparation and optical study of polymer heterostructures, such as Distributed Bragg Reflectors (DBR) and planar microcavities. We demonstrate high accuracy and reliability of a cheap spin-casting technique for the realization of large-size and flexible polymer DBR. A defect layer of emitting F8BT – designed and synthesized ad-hoc - is sandwiched between two DBRs to create a microcavity, or on top surface of the DBR to create a Bloch Surface Wave (BSW) structure
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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