1,720,967 research outputs found
Decoration of Porous Silicon with Gold Nanoparticles via Layer-by-Layer Nanoassembly for Interferometric and Hybrid Photonic/Plasmonic (Bio)sensing
Full text linkGold nanoparticle layers (AuNPLs) enable the coupling of morphological, optical, and electrical properties of gold nanoparticles (AuNPs) with tailored and specific surface topography, making them exploitable in many bioapplications (e.g., biosensing, drug delivery, and photothermal therapy). Herein, we report the formation of AuNPLs on porous silicon (PSi) interferometers and distributed Bragg reflectors (DBRs) for (bio)sensing applications via layer-by-layer (LbL) nanoassembling of a positively charged polyelectrolyte, namely, poly(allylamine hydrochloride) (PAH), and negatively charged citrate-capped AuNPs. Decoration of PSi interferometers with AuNPLs enhances the Fabry-Pérot fringe contrast due to increased surface reflectivity, resulting in an augmented sensitivity for both bulk and surface refractive index sensing, namely, about 4.5-fold using NaCl aqueous solutions to infiltrate the pores and 2.6-fold for unspecific bovine serum albumin (BSA) adsorption on the pore surface, respectively. Sensitivity enhancing, about 2.5-fold, is also confirmed for affinity and selective biosensing of streptavidin using a biotinylated polymer, namely, negatively charged poly(methacrylic acid) (b-PMAA). Further, decoration of PSi DBR with AuNPLs envisages building up a hybrid photonic/plasmonic optical sensing platform. Both photonic (DBR stop-band) and plasmonic (localized surface plasmon resonance, LSPR) peaks of the hybrid structure are sensitive to changes of bulk (using glucose aqueous solutions) and surface (due to BSA unspecific adsorption) refractive index. To the best of our knowledge, this is the first report about the formation of AuNPLs via LbL nanoassembly on PSi for (i) the enhancing of the interferometric performance in (bio)sensing applications and (ii) the building up of hybrid photonic/plasmonic platforms for sensing and perspective biosensing applications
Ultrathin Ambipolar Polyelectrolyte Capacitors Prepared via Layer-by-Layer Assembling
Full text linkMiniaturized solid state capacitors leveraging migration of unipolar ions in a single polyelectrolyte layer sandwiched between metal electrodes, namely, polyelectrolyte capacitors (PECs), have been recently reported with areal capacitance up to 100–200 nF mm−2. Nonetheless, application of PECs in consumer and industrial electronics has been hindered so far by their small operational frequency range, up to a few kHz, due to the resistive behavior (phase angle >−45°) of PECs in the range kHz-to-MHz. Here, it is reported on multilayer polyelectrolyte capacitors (mPECs) that leverage as dielectric an ambipolar nanometer-thick (down to 10 nm) stack of anionic and cationic polyelectrolytes assembled layer-by-layer between metal electrodes to eliminate the resistive behavior at frequencies from kHz to MHz. This significantly extends the operational range of mPECs over PECs. mPECs with areal capacitance as high as 25 nF mm−2 at 20 Hz and full capacitive behavior from 100 mHz to 10 MHz are demonstrated using different assembling conditions and anionic/cationic polyelectrolyte pairs. The mPECs reliably operate over time for >300 million cycles, at different biasing voltages up to 3 V, and temperatures up to 80 °C, showing a reversible capacitive behavior without significant hysteresis. Application of mPECs in flexible electronics, also operating at high frequency, is envisaged
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
Layer-by-layer nano-assembly of charged polyelectrolytes for label-free optical biosensing with nanostructured materials: The case of nanostructured porous silicon interferometers
No full textThe nano-assembly of charged polyelectrolytes via layer-by-layer (LbL) technology on porous silicon (PSi) interferometers is here demonstrated as an effective biofunctionalization approach for high-sensitivity/selectivity labelfree optical biosensing, using streptavidin/biotin affinity detection as case study. Nanostructured PSi interferometers are biofunctionalized with a nano-assembly of a positively-charged polyelectrolyte, namely, PAH (poly(allylamine hydrochloride)), and a negatively-charged biotinylated polyelectrolyte, namely, b-PMAA (poly(methacrylic acid)), via LbL technology. The nano-assembly is stable under operating conditions and enables the selective and sensitive detection of streptavidin with a sub-picomolar detection limit (namely, DL=0.6 pM), which is 105-fold lower than that achieved with PSi interferometers biofunctionalized using standard silane chemistry. Remarkably, the analytical performance achieved for LbL-biofunctionalized PSi interferometers is comparable to those of state-of-the-art label-free photonic and plasmonic platforms
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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