1,720,965 research outputs found
Portable detection system for Ochratoxin A by real time chromatography and a-Si:H photodiodes
No full textIn this paper, we report on the design, fabrication and characterization of a low cost, portable detection system able to quantify, in a rapid and reliable way, the contamination level of Ochratoxin A (OTA) in red wine. The operating principle is the real-Time monitoring of the natural fluorescence of OTA molecules during a chromatographic run on a thin layer chromatographic plate. The fluorescence is detected by an array of amorphous silicon photosensors whose photocurrents are directly proportional to the amount of OTA molecules present in the sample under analysis. By comparison with a reference sample the system is able to determine if the OTA contamination level is below or above the limit law for each food commodity. The system performances have been verified in real matrices analyzing several samples extracted from red wines obtaining a minimum detectable quantity of 0.2ng. © 2017 IEEE
Seismic isolation of lead-cooled reactors: The European project siler
No full textSILER (Seismic-Initiated event risk mitigation in LEad-cooled Reactors) is a Collaborative Project, partially funded by the European Commission in the 7th Framework Programme, aimed at studying the risk associated to seismic-initiated events in Generation IV Heavy Liquid Metal reactors, and developing adequate protection measures. The project started in October 2011, and will run for a duration of three years. The attention of SILER is focused on the evaluation of the effects of earthquakes, with particular regards to beyond-design seismic events, and to the identification of mitigation strategies, acting both on structures and components design. Special efforts are devoted to the development of seismic isolation devices and related interface components.Two reference designs, at the state of development available at the beginning of the project and coming from the 6th Framework Programme, have been considered: ELSY (European Lead Fast Reactor) for the Lead Fast Reactors (LFR), and MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) for the Accelerator-Driven Systems (ADS).This paper describes the main activities and results obtained so far, paying particular attention to the development of seismic isolators, and the interface components which must be installed between the isolated reactor building and the non-isolated parts of the plant, such as the pipe expansion joints and the joint-cover of the seismic gap
Siler project: Design of the seismic isolators
No full textThis paper describes the SILER (Seismic-Initiated event risk mitigation in LEad-cooled Reactors) Project results obtained so far in the design of the seismic isolation system of two nuclear power plants: the ELSY configuration for the LFR (Lead-Cooled Fast Reactor) design and the MYRRHA configuration for the accelerator-driven systems (ADS). The seismic protection of the nuclear buildings by means of seismic isolation has been chosen in order to minimize changes to the standard design of the civil works and internal components of the Nuclear Power Plant. The work led to the identification of the optimal design solution, in terms of type and location of seismic devices, to achieve compliance to the floor response acceleration spectra in horizontal and vertical direction, with levels of horizontal displacements not exceeding the maximum acceptable values for structural and non-structural elements. The isolators studied in the project are of the type elastomeric, both High Damping Rubber Bearings and Lead Rubber Bearings; moreover the adoption of a fail-safe system to limit the horizontal isolator deformation in case of beyond design earthquakes is studied
The Spatio-Temporal Variability of Frost Blisters in a Perennial Frozen Lake along the Antarctic Coast as Indicator of the Groundwater Supply
Full text linkRemote sensing, and unmanned aerial vehicles (UAVs) in particular, can be a valid tool for assessing the dynamics of cryotic features as frost blisters and to monitor the surface changes and the sublimation rates on perennially frozen lakes that host important ecosystems. In this paper, through the use of these remote sensing techniques, we aim to understand the type of groundwater supply of an Antarctic perennial frozen lake that encompasses two frost blisters (M1 and M2) through the temporal analysis of the features’ elevation changes (frost blisters and lake ice level). The frozen lake is located at Boulder Clay (northern Victoria Land, Antarctica). We relied on several photogrammetric models, past satellite images and ground pictures to conduct differencing of digital elevation models, areal variations and pixel counting. In addition, in situ measurements of the ice sublimation or snow accumulation were carried out. The two frost blisters showed different elevation trends with M1 higher in the past (1996–2004) than recently (2014–2019), while M2 showed an opposite trend, similarly to the ice level. Indeed, the linear regression between M2 elevation changes and the ice level variation was statistically significant, as well as with the annual thawing degree days, while M1 did not show significant results. From these results we can infer that the groundwater supply of M1 can be related to a sublake open talik (hydraulic system) as confirmed also by pressurized brines found below M1, during a drilling in summer 2019. For M2 the groundwater flow is still not completely clear although the hydrostatic system seems the easiest explanation as well as for the uplift of the lake ice
A new nanostructured stationary phase for ultra-thin layer chromatography. A brush-gel polymer film
No full textWe report here on the fabrication and the characterization of a new stationary phase for ultrathin layer chromatography (UTLC) based on a brush-gel polymer film obtained by cross-linking poly(glycidyl methacrylate) and di(ethylene glycole)dimethacrylate. The use of polymer brushes to design ultra thin layer chromatography plates opens interesting perspectives. Very thin polymer films can be covalently grafted on a glass surface with virtually any chemical functionality. By selecting and/or chemically modifying suitable monomers, stationary phases characterized by high affinity for specific substances can be accurately tailored. The structure of the brush gel formed on glass substrates was characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Atomic Force Microscopy (AFM) and Field-Emission Scanning Electron Microscopy (FESEM). The efficiency of poly(GMA-co- DEGDMA)-NH2 UTLC stationary phase compares very well with that of silica-gel TLC and other UTLC devices. However, the separation of a fluorescent dyes mixture with our UTLC device occurs faster and with less solvent compared to typical TLC methods. In addition the same plate can be re-used several times for multiple analyses without any reduction of the separation efficiency.Copyright © 2013 American Scientific Publishers
Performances of on-chip integrated amorphous silicon photodiodes for chemiluminescence and bioluminescence-based assays
No full textChemiluminescence (CL) and bioluminescence (BL)-based
microfluidic chips are being increasingly proposed for clinical,
agrofood and environmental analyses . Although offering
high detectability and specificity, CL reactions generally involve
the emission of low light levels, thus requiring highly sensitive
detectors for their sensitive measurement. To enable
point-of-care (POC) applications, full integration of all the system
components in a low-cost microfluidic platform is required.
Herein, we describe a microfluidic-based analytical device
integrating an array of 16 hydrogenated amorphous silicon
(a-Si:H) photodiodes [3] for on-chip detection of CL signals
and the evaluation of its analytical performance, as compared
with a state-of-the-art cooled slow-scan charge coupled device
(CCD)-based acquisition system (Night Owl LB 981, Berthold
Technologies). The a-Si:H photodiodes, which are p-doped/
intrinsic/n-type stacked structures, were deposited by Plasma
Enhanced Chemical Vapour Deposition (PECVD) on a glass
substrate covered with an indium tin oxide (ITO) layer. An array
of polydimethylsiloxane (PDMS) microwells were bonded to the
opposite side of the glass for CL measurements
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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