1,720,981 research outputs found
5-Phenyl-dipyrromethane and 5-(4-pyridyl)-dipyrromethane as modular building blocks for bio-inspired conductive molecularly imprinted polymer (cMIP). An electrochemical and piezoelectric investigation
No full text5-Phenyl-dipyrromethane (5-ph-DP) and 5-(4-pyridyl)dipyrromethane (5-py-DP) are proposed, for the first time, as electroactive building blocks for the preparation of sensors based on molecularly imprinted conductive polymers (cMIP). This paper reports the electrochemical and gravimetric investigation on 5-phenyl-dipyrromethane and 5-(4-pyridyl)dipyrromethane and it demonstrates their ability to form both conductive homo-polymers (cMIP) and co-polymers (co-cMIP). The template salicylic acid (SA) was reversibly and selectively incorporated in the obtained synthetic pockets as proved by both voltammetric and piezoelectric investigation. Moreover, the sensitivity of co-cMIP was higher compared to the two homopolymers. The analytical performances confirm that dipyrromethanes, properly functionalized, can be used as electroactive amino acid-like monomers, to prepare bio-inspired imprinted polymers. © The Royal Society of Chemistry 2015
Electrochemical detection of hydrogen peroxide by free standing nickel oxide plastic electrode
No full textOptimization of an OLED-based immunosensor for the detection of tetrodotoxin in mussels
No full textAlien species have colonized new aquatic ecosystems due to multifactorial effects, among which climate change or the increasing marine traffic, can be mentioned. The occurrence of contamination due to tetrodotoxin (TTX) is now observed in the Mediterranean Sea and in bivalves, whereas TTX was classically contaminating pufferfish in the Pacific Ocean. In this paper, we present the optimization of an Organic Light Emitting Diode (OLED) based immunosensor to detect tetrodotoxin in spiked samples of mussels. An ELISA test was preliminary optimized to set the concentrations of all biological elements required to develop the OLED-immunoaffinity-based biosensor and to mutually validate the two detection systems presently optimized. The threshold concentration of 44 ng g−1 set by EFSA for TTX in seafood products was used to distinguish the negative mussel samples from the positive ones. A streamlined extraction protocol was adopted after its optimization to fulfil the need of the assay (European Food Safety Authority, 2017)
Development of a point of care (POC) test as an immunobiosensor for okadaic acid detection in mussels
Full text linkThe increase in frequency and intensity of potential risks concerning the exposure of seafood to diarrhetic shellfish poisoning (DSP) toxins, even in areas not traditionally accomplished, raises the number of monitoring analyses for the detection of this class of toxins to guarantee the food safety of the products. In addition to the analysis performed with liquid chromatography-tandem mass spectrometry (LC-MS/MS), reference method in EU, semiquantitative rapid tests for preliminary screening and rapid monitoring plan are applied. Different kits for the detection of DTX family toxins are available on the market, but they require specialised labs and the cost of the analysis per sample is quite high. Based on the current situation, developing an easy-touse and cheap test for measuring okadaic acid, as the main responsible for DSP poisoning, for the implementation of point-of-care (POC) systems is desirable. An immunobiosensor test, based on immunoaffinity reaction utilizing commercially available monoclonal antibodies, has been optimized and validated for the detection of okadaic acid in mussel (Mytilus galloprovincialis) extracts, with a limit of detection of 60 mu g/kg, a sensitivity of 0.68 n degrees of counts/ ug/Kg and a screening test range between of 60-350 ug/kg. The proposed POC immunoassay provides results comparable (r = 0.981) to the ones obtained by other semiquantitative rapide tests, like enzymatic assay applied for routine monitoring plans for the detection of the dinophysistoxins (DTXs) family. The goal of the presented test is the reduction of steps for the toxin extraction and a relevant reduction of the time for the analysis and the provision of a cheap POC analysis system
NiO-nanoflowers decorating a plastic electrode for the non-enzymatic amperometric detection of H2O2 in milk: Old issue, new challenge
No full textIn food supply chain, there are regulatory limitations on the use of chemicals for cleaning processing lines since the healthiness of the commodities must be guaranteed if accidently traces of these detergents and sanitizers pass to them. Hydrogen peroxide, is a commonly used sanitizer in the cleaning of the food processing lines having both bactericidal and bacteriostatic properties, however, it produces inflammatory effects on the human body. The availability of rapid systems to detect its accidental presence is therefore useful to speed up the control and apply corrective actions. In the present work, a drop casting and easily prepared plastic graphite/PVC electrode decorated with NiO nanostructures has been investigated as electrochemical sensor for the non-enzymatic amperometric determination of H2O2. The catalytic activity, dispersion, and stability of NiO nanostructures mixed with plastic nanocomposite electrode have been studied in detail. The preparation method, particularly the precipitating agents used in the synthesis of NiO nanostructures strongly influenced their morphology and porosity. Further, the electrochemical response of NiO-PE electrodes towards H2O2 resulted to be morphology-dependent. The non-enzymatic electrochemical sensor was optimized for the rapid and sensitive detection of H2O2 present in milk with no sample pre-treatments. NiO nanoflowers showed the best catalytic activity towards H2O2, a linear range that extends up to 4 mM and a LOD of 5 μM (3sd of the blank signal) were obtained
POM@PMO plastic electrode for phosphate electrochemical detection: a further improvement of the detection limit
Full text linkThe development of a highly sensitive electrochemical sensor (E-sensor) is described based on stand-alone plastic electrodes (PE) for phosphate detection, being an essential nutrient in the marine environment. The detection mechanism is based on the chemical affinity between polyoxomolybdate anions (POM) and orthophosphate to form an electroactive phosphomolybdate complex. The custom-made E-sensor was formulated with an organic octamolybdate derivative (TBA4Mo8O26) incorporated with periodic mesoporous organosilica (PMO) to obtain a significant improvement in the analytical performances of phosphate determination. This POM@PMO combination was found to be advantageous in the determination of low concentrations of phosphate in standard solutions ranging from 1 to 500 nM, using square wave voltammetry as the detection technique. This sensitivity enhancement can be attributed to the effect of hydrophobic PMO in loading more POM moieties, owing to its highly porous structure and charged shell. Consequently, the POM@PMO-PE sensor achieved a competitive sensitivity of 4.43 ± 0.14 μA.nM−1.cm−2 and a limit of detection of 0.16 nM with good selectivity against silicates. Finally, seawater and treated wastewater samples have been tested to validate the sensor response in comparison to the official method of phosphate determination. Graphical abstract: [Figure not available: see fulltext.
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
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