1,721,033 research outputs found
Nanostructured (Bio)sensors for smart agriculture
No full textIntense farming represents one of the main sources causing detriments to vital resources as lands and water, due to unsustainable agricultural practices and the resulting environmental pollution. Furthermore, the increasing world population and the impact of climate change contribute to worsen these constraints. To these regards, several attempts have been completed to provide pioneering technologies for facing against these challenges, including nanostructured (bio)sensors. Indeed, nanotechnology-based (bio)sensors, thanks to the exploitation of fascinating properties of functional materials at the nanoscale, can support farmers in delivering fast, accurate, cost-effective, and in field analyses of i) soil humidity, ii) water and soil nutrients/pesticides, and iii) plant pathogens. Herein, we report a glance of the nano nanostructured (bio)sensors developed to support smart agriculture, reporting representative examples form the literature of the last 10 years. (C) 2017 Elsevier B.V. All rights reserved
Sustainable materials for the design of forefront printed (bio)sensors applied in agrifood sector
No full textThe search for sustainability has now become a duty for all those entities, nations or people who intend to combat poverty in the world, safeguard the environment and bridge the gap of disparities that unfortunately still exist between underdeveloped countries and medium-high developed nations.The agrifood sector plays an important role in this vision, and the development of sustainable analytical devices at low cost and easy to use for everyone, suitable for being adopted by those countries whose technological development does not allow them to take up expensive and sophisticated laboratory techniques, may constitute a contribution towards achieving the objectives listed above.In this review we illustrate some examples of electrochemical devices realized utilizing sustainable materials, such as paper, as support for disposable and reagent-free (bio)sensors applied to the monitoring of food quality and safety. We also mention the first applications of new carbonaceous materials obtained from the recycling of agrifood waste products, which promise interesting features for electrochemical applications. (C) 2020 Elsevier B.V. All rights reserved
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
Reusable optical multi-plate sensing system for pesticide detection by using electrospun membranes as smart support for acetylcholinesterase immobilisation
No full textHerein we report a multiplated and biopolymeric-based optical bioassay for organophosphate detection based on the use of acetylcholinesterase (AChE) as biocomponent and biopolymeric electrospun fibrous mats as eco- designed supports for AChE immobilisation. The principle of the detection relays on the decrease of enzymatic activity due to the capability of the organophosphorus pesticides to irreversibly inhibit AChE, which is optically detected using Ellman colorimetric method. The proposed bioassay consists in a novel, cost-effective, and multiplex-based 96-well system, in combination with customised biopolymeric membranes modified with AChE, with the aim to deliver a sustainable analytical tool. Indeed, the designed set-up should provide and guarantee several advantages, including: i) the re-use of plastic multi-plate with the only replacement of polymer dishes in the case of inhibition absence; ii) the exploiting of the properties of the immobilised enzyme, i.e. multiple analysis using the same amount of enzyme, reducing the AChE amount for analysis. In detail, three different biopolymers (i.e. polylactic acid (PLA), polycaprolactone (PCL), and poly-hydroxybutyrate-co-hydroxyvalerate (PHBV)) were investigated and morphologically characterised, as supports for enzyme immobilisation, to identify the optimal one. Among them, PHBV was selected as the best support to immobilise AChE by cross- linking method. The analytical features of the bioassay were then assessed by measuring standard solutions of paraoxon in a range of concentrations between 10 and 100 ppb, achieving a linear range up to 60 ppb and a detection limit of 10 ppb. Thus, the suitability of this sustainable bioassay to detect organophosphate at ppb level was demonstrated
EFFORTS, CHALLENGES, AND FUTURE PERSPECTIVES OF GRAPHENE-BASED (BIO)SENSORS FOR BIOMEDICAL APPLICATIONS
No full textCommercial brucite, a worldwide used raw material deemed safe, can be contaminated by asbestos
No full textBrucite is a raw material used in several applications and worldwide traded. The main active deposits are located in North America, North Europe and China and the extracted material is worked and delivered all over the world without any particular precaution as it is considered a safe inert product. But is it really true? Applying a consolidated protocol of analysis for the detection and characterization of fibers, we found asbestos in a sample of commercial brucite. The analyzed material is primarily composed of plate-like crystals of brucite; nevertheless, chemical and mineralogical analyses revealed the presence of serpentine, while morphometric observation through electron microscopy confirmed the occurrence of respirable regulated chrysotile (serpentine asbestos) fibers. The individual fibers making up the chrysotile bundles have length >5 μm, width <3 μm, length/width ratio >3, and their concentration in the investigated product is 169 mg/kg (0.02 wt%). Although paragenesis of brucite with chrysotile has been known for a long time, never before was documented a commercial brucite, distributed worldwide, contaminated with asbestos. In the light of these results, we think that certification of the absence of asbestos should be imposed to the brucite mining companies and distributors; otherwise, users should always include a careful inspection on incoming materials, at least by electron microscopy, to rule out the occurrence of asbestos
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
Paper-Based Electrochemical Devices in Biomedical Field: Recent Advances and Perspectives
No full textElectronic equipment generated 9 million tons of waste in 2005 in EU, and it is expected to grow to more than 12 million tons by 2020. To decrease the environmental pollution of electronics, the development of sustainable sensors, including paper-based electrochemical devices, are attracting growing interest thanks to their cost-effectiveness, suitability for in situ analysis, and environmentally friendly. The development of the paper-based devices as point of care is a paramount issue, since this type of systems meets the requirements of the ASSURED criteria coined by WHO, which describe the ideal characteristics of a diagnostic test, and, as a matter of fact, paper-based (bio)sensors with electrochemical detection practically match this criteria, as they are Affordable (by those at risk of infection), Sensitive (low false-negatives), Specific (few false-positives), User-friendly (simple to perform and requiring minimal training), Rapid (to give useful information at first visit) and Robust (do not require refrigerated storage), Equipment-free, Delivered to those who need it. This chapter (with 73 refs.) covers the recent progresses on paper-based electrochemical (bio)sensors for biomedical field, giving an overview of the different papers and techniques used for the fabrication of paper-based devices as well as the different configurations designed. The main section encompasses the description of several paper-based sensors and biosensors (i.e., enzymatic, immuno- and nucleic acid-based sensors) with biomedical applications as well. The last section describes the future perspectives for eco-designed (bio)sensors, being a hot topic in the field of analytical sensing tools
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