1,721,017 research outputs found
Organic field-effect transistor for label-free dopamine sensing
No full textWe describe a potentiometric sensor based on Electrolyte-Gated Organic Field-Effect Transistor (EGOFET) for “in vitro” detection of dopamine. The sensing element of this device resides at the Au gate–aqueous solution interface by means of a self-assembled monolayer (SAM) composed by cysteamine and 4-formylphenyl boronic acid. The covalent and selective adsorption of dopamine induces a surface dipole potential which shifts the electrode work function and modulates the double layer capacitance. As a result, our device is capable to detect dopamine up to pico-molar concentration showing higher sensitivity with respect to other approaches. For this reason the interface engineering of our EGOFET gate is a promising route for diagnostic applications
Modification of the gate electrode by self-assembled monolayers in flexible electrolyte-gated organic field effect transistors: Work function: Vs. capacitance effects
No full textUnderstanding the physics behind the operational mechanism of Electrolyte-Gated Organic Field-Effect Transistors (EGOFETs) is of paramount importance for the correct interpretation of the device response. Here, we report the systematic functionalization of the gate electrode of an EGOFET with selfassembled monolayers with a variety of dipolar moments showing that both the chemical nature and the monolayer density influence the electrical characteristics of the devic
Monitoring of Lactococcus lactis growth based on Reduced-Graphene Oxide TFT for Dairy Industry Applications
Full text linkGoing 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
Morphological and mechanical properties of alkanethiol self-assembled monolayers investigated via bimodal atomic force microscopy
No full textAlkanethiol Self-Assembly Monolayers (SAMs) were investigated by means of BiModal Atomic Force Microscopy. Morphological and mechanical properties show a parabolic trend vs. the chain length n, which is ascribed to the disorder at the SAMs/Au interface. This explains the trend of charge injection across SAMs in organic field effect transistor
Mercury-Mediated Organic Semiconductor Surface Doping Monitored by Electrolyte-Gated Field-Effect Transistors
No full textSurface doping allows tuning the electronic structure of semiconductors at near-surface regime and is normally accomplished through the deposition of an ultrathin layer on top or below the host material. Surface doping is particularly appealing in organic field-effect transistors (OFETs) where charge transport takes place at the first monolayers close to the dielectric surface. However, due to fabrication restrictions that OFET architecture imparts, this is extremely challenging. Here, it is demonstrated that mercury cations, Hg2+, can be exploited to control doping levels at the top surface of a thin film of a p-type organic semiconductor blended with polystyrene. Electrolyte- or water-gated field-effect transistors, which have its conductive channel at the top surface of the organic thin film, turn out to be a powerful tool for monitoring the process. A positive shift of the threshold voltage is observed in the devices upon Hg2+ exposure. Remarkably, this interaction has been proved to be specific to Hg2+ with respect to other divalent cations and sensitive down to nanomolar concentrations. Hence, this work also opens new perspectives for employing organic electronic transducers in portable sensors for the detection of an extremely harmful water pollutant without the need of using specific receptor
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
Diffusion of Thyme, Cinnamon and Oregano essential oils in different nanocellulose matrices
Full text linkSolubility and diffusivity of Thyme, Cinnamon and Oregano essential oils in nanocellulose films, with different carboxymethylation degree, were investigated in view of potential use in active packaging applications.Solubility of liquid essential oils resulted to increase with the carboxymethylation degree for both Oregano and Thyme, while it was non-monotonous for Cinnamon. Thyme showed the higher solubility (about 20%wt) followed by Cinnamon and Oregano.The sorption kinetics of liquid essential oils was substantially Fickian. The diffusivity also increased with the increase of the carboxymethylation degree, going from 9.6 × 10−9 cm2⁄s, observed for oregano in pure nanocellulose, to 2.0 × 10−8 cm2⁄s, measured for Cinnamon in the most charged one.The release in vapor phase showed two different kinetics: a faster one dominating at short times and a slower one visible at long times. Fickian diffusion described the behaviour of most of the samples even if in some case data were better fitted by using exponential functions. In general, Diffusivities values ranged from 10−9 to 10−11 cm2⁄s for the fast process and from 10−11 to 10−13 cm2⁄s, for the slow one.Carboxymethylation degree also affected the release kinetics of antimicrobial essential oils, which therefore can be tuned by appropriate choice of the nanocellulose material
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